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EcoFlow vs. Victron Energy Electrical System Comparison
Like many, we were excited about these “future of electrical system” kits. We bought a 5kWh kit and, initially, we were quite smitten indeed. What a beauty! A few months later the honeymoon period ended. Alas, after much testing and, trying to kindle the love, our cupid never showed. In this post, we’ll do our best to compare an EcoFlow Power Kit (specifically the 5kWh “Independence” Power Kit) to a “traditional” system using high-quality, value-priced 12-volt lithium batteries and a bunch of top-quality Victron Energy components and explain why we’re sticking with the Blue Power. But, You’re Biased! Yeah, that’s a bit true, but not exactly what you think. It’s worth pointing out that selling EcoFlow products is very profitable (notice how many ads there are for these things). In fact, we’d actually earn more money selling you an EcoFlow kit vs. the Victron bundles we discuss in this post. We did sell the Power Kits for a few months but decided to stop selling them recently after considering the limitations. We take our pledge to only sell the very best, road-tested products – the stuff we’d use in our vans very seriously. What follows are the reasons we wouldn’t use an EcoFlow kit in our vans – even if we were DIY’ers who were not experienced with electrical systems. Changes with V2 Power Kits – Update Late 2024 In late 2024, EcoFlow began promoting their new “v2” Power Kits and changed the naming convention to refer to the Power Hub’s output capacity instead of the battery capacity. The new 5kVA model can support 120VAC loads up to around 4000 watts (5000 watts surge). This is neat but we find that AC loads tend to be pretty minimal in camper vans. Apparently the inverter is quieter as well. On the AC side they also added charging from and passthrough of 240VAC to loads when that higher voltage shore power is available. The new kits have a dedicated port for direct connection to the 48VDC battery power so you don’t need to sacrifice a battery connection port to run something like a 48-volt DC air conditioner. In my view the most practical upgrade for a van/RV is the increase to 100 amps of 12VDC power (or 60 amps at 24-volt). EcoFlow also has a new Power Link accessory/add-on that adds some extra connectivity to the outside world like RV-C/NMEA2000 CAN and resistive tank sensors which is a nice upgrade path. When it comes to alternator charging, the specs state that you can have three inputs (13V-60V, 60A/30A/30A, up to 4800W total) but I don’t know of any way to actually provide that from a factory vehicle alternator or secondary alternator with an external regulator such as the Wakespeed. If someone figures this out, please let us know! The Short Version The EcoFlow products are beautifully designed and generally work well if you don’t need advanced features. By far, the biggest advantage of an EcoFlow Power Kit over a professionally installed Victron system is how simple it is for a non-experienced DIY’er to install and configure the system. This benefit does not disappoint and we were duly impressed. Overall, it’s actually a great system and ideal in certain situations. If the limitations we present in this post are not relevant to you, then EcoFlow is a great option. However, as you’ll see later in this post, at today’s prices, you can get everything you need for a comparable (arguably better) Victron system for about $1,900 less than the EcoFlow kit which is about the cost of having an experienced professional installer wire up your Victron system. That is what we’d recommend to most people so that you’re not subject to the limitations we detail in this post and you can have true confidence in your system – both that it will work well and that it will be maintainable and upgradable for the life of your rig. We even have a directory of installers you can browse and, if you’re in our area (Florida) we have some trusted installers we can recommend if you reach out. Ugh, Math Let’s get some math stuff out of the way. If you don’t like math, ya can skip this part… Battery capacity is often measured in amp hours (Ah). But, power consumption is better measured in watts. So, many people refer to the capacity in a system with kilowatt watt hours (kWh) which takes into consideration of the system voltage. To convert between amp hours and kilowatt hours you multiply the amp hours by the voltage. To do the reverse (get amp hours from kilowatt hours) you divide the kilowatt hours by the volts. In our testing of our EcoFlow Power Kit the 12-volt option operates at 13.8 volts. In systems using 12-volt batteries, the voltage is going to be anywhere between 14.4 on the high end, to 12 on the low end, depending on the battery state of charge (SOC). So, when we do conversions, we’ll use the average of those – 13.2 – as the voltage value. For instance, to convert a 5kWh EcoFlow battery to amp hours for a 12-volt system, we’ll divide the specification of that Power Kit Battery of 5,120 by 13.2 to arrive at 387 amp hours. Or, to convert a 314 amp hour rated SOK battery to kilowatt hours we’d multiply 314 by 13.2 to arrive at 4,145. We think this is fair math but you can grab your calculator and adjust that voltage value for yourself if you want to see the impact of using something like 12.8 volts. If you’re not familiar with EcoFlow Power Kits, the most popular of them is a 5kWh “Independence” version. It comes with: One 5kWh battery (5,120 kilowatt hours) which is equivalent to a 387 amp hour battery (at 13.2 volts). Up to 2x additional 5kWh batteries can be added to the system. At today’s prices, they are about $4,600. The Power Hub, which is where most of the components of the system connect to (batteries, shore power inlet, solar input, DC-DC charger input, and the output for all loads). Compared to a traditional/Victron system, it acts as the inverter/charger, DC-DC charger, solar charge controller, etc. A combination 120-volt AC and 12/24-volt DC load center. The EcoFlow batteries are natively 48-volt but this is converted for use with your DC loads (lights, fans, water pump, etc.). You can select between 12 or 24-volts. It can provide a maximum of 1,000 watts of DC power to the DC load center which is about 70-75 amps in a 12-volt configuration. A “console” which is the touchscreen that provides control and monitoring for the system. All the wiring needed to hook the system up – shore power inlet, wiring to your vehicle battery for DC-DC (alternator) charging, MC4 solar power cables, etc. The only wiring you need to provide are for the branch circuits that come from the combination AC/DC load center and power your actual loads in the rig. Compare the Specs Speaking of math, if you’re engineering-minded and want to dive into all the numbers, we’ve made a comparison sheet between the systems we’re discussing in this post in this Google Sheet. EcoFlow Power Kit Limitations Customer Service/Tech SupportIt’s no secret that EcoFlow has less than stellar customer and technical support. Some people describe it as “the worst” or “non-existent”. To be fair, others have had great luck. However, we put a lot of time and effort into having the very best customer service in the industry (don’t take it from us, read our customer reviews) and when the manufacturer doesn’t pull their weight in this regard it can reflect poorly on us. We don’t want to rely on “luck”. So, this was part of our decision to stop selling their products. Lack of ModularityOne of the awesome features of the EcoFlow is that it’s easy to install and there are only a few bits and pieces. But, this also means that there is no modularity. So it’s a bit of a double-edged sword and you’ll have to decide which side of that blade you’d like to fall on. The simplicity of the EcoFlow is great for sure but it creates single points of failure. It’s very handy to be able to swap out a single component if it fails while the rest of the system keeps working. For instance, if your Victron solar charge controller kicks the bucket, you can keep charging other ways such as DC-DC (alternator) charging or shore power. On an EcoFlow kit, these are all inside one box. A traditional system, with lots of individual blue boxes, allows you to stay on the road and limp to the next dealer. Also, any Victron component with the word “smart” in the name can be configured and monitored via Bluetooth with their VictronConnect app. It’s very helpful to be able to monitor and see historical data on each specific component in your system when troubleshooting any issues. Limited Parts Availability Speaking of dealers, Victron Energy has distributors and dealers literally around the world. So, if you’re in limp mode with your power system, you will be able to find the parts and the support and installation professionals you need just about everywhere you might find yourself. In our experience, getting parts for EcoFlow Power Kits is very much the opposite. There are very few stocking dealers of EcoFlow and they don’t have all the fiddly bits you might need. This is made worse by the proprietary nature of their connections. One example: we ordered a replacement battery cable for the Power Kits that has a proprietary connection on each side. We patiently waited for over 3-weeks for this cable and were eventually told that it would be many more before it would ship. Keep in mind this is the cable that connects the batteries to the Power Hub! So, if it fails or breaks or your dog chews through it, you have no power. For us, it was only inconvenient since we are just testing this stuff in our mad van laboratory, but if you were on the road, this would put you completely out of business for way too long. Closed EcosystemOne of the things we love about Victron Energy is that you can “use what you want” from their product lineup and not be locked into “everything” Victron. For instance, in the example Victron system we’re actually using SOK batteries because of their impressive price/performance. Of course, we also sell and recommend Victron batteries – particularly if you’re building out a system with a secondary alternator. In a EcoFlow system, pretty much everything but your solar panels are going to need to be from EcoFlow. Another example is Victron’s Venus OS which powers their GX devices like the Cerbo GX which is an absolutely brilliant device for controlling and monitoring Victron gear. But, it also works with 3rd-party stuff like SeeLevel tank monitor and Ruuvitag sensors. The open ecosystem allows you to add some super cool functionality to your rig and this ecosystem continually grows to become increasingly vibrant over time. Victron also regularly updates firmware for all their devices – generally through Bluetooth and their VictronConnect app. Some who use Victron equipment might say it’s too often! But, these upgrades often come with new features and functionality that are completely free! High Cost of Adding Battery StorageLater in the post, in the cost comparison section, you’ll see that the example Victron system starts with more battery storage capacity than the 5kWh EcoFlow kit (over 40% more) and if you wanted, you could quite easily add a third, 280Ah (3,696 kWh) SOK battery for $1,149 at today’s prices (even less than that if ordered in our bundle) which comes out to about $.31/kWh or storage. Compare that to an EcoFlow 5kWh (technically 5,120) battery that is selling for $4,600 today which is well over twice the cost per kWh of storage at around $.89. This goes back to the advantage of modularity and not being locked into a closed ecosystem of products. This is an example of how being “stuck” in a closed ecosystem can be expensive. DC Output Limits – Not Great for DC Air ConditionThe DC output to the AC/DC distribution panel is limited to 1,000 watts (75 amps when set to 12-volt mode). This isn’t much of a limitation in most cases. But, if you’re in Florida (or similar), and want to run a 12-volt DC air conditioner it becomes a major limitation. Many of these DC air conditioners use around 55-60 amps when running on high (check out our comparison sheet). So, if you are running your AC unit on high, you’re only left with around 15 amps for ALL of your 12-volt loads such as refrigerators, water pumps, Maxxfans, etc. which just isn’t enough leftover juice to use a few of those things simultaneously with a DC air conditioner. Also, there isn’t a simple way to wire up the heavy-gauge wire (like 4 AWG) from the AC unit to the EcoFlow AC/DC distribution panel. You can “hack” the wiring in a few ways but, at this time, you can’t get any more juice. The EcoFlow Power Kits have plenty of 120-volt AC power to run a more traditional rooftop unit but if you look closely at the specifications of those they typically use about twice as much power as a 12-volt DC air conditioners. So, if you want to stay cool off-grid, you’d likely need to pay for extra batteries which are, as we’ve already noted, very expensive. The workaround is to use a 48-volt air conditioner with the EcoFlow that connects directly to the 48-volt battery “bus” but you’ll still have to fight with the proprietary connectors on the EcoFlow Power Hub/battery. No Secondary Alternator for YouWe are big fans of getting the most out of your vehicle engine. Since you’re driving around anyway, why not get massive power from a dedicated secondary alternator or heat your water while you cruise down the road? With a Victron system, you can integrate secondary alternator charging into your system with ease and no limitations. EcoFlow Power Kits have an integrated DC-DC charger similar to the Victron Orion XS units. The input labeled for “alternator” is rated for up to 60 amps and allows for up to 1600 watts. In our example Victron system we show 2x Orion XS DC-DC chargers running in parallel for a maximum charge of 100 amps (1,320 watts). A Nations secondary alternator system with a Wakespeed regulator can charge at over 3,000 watts (!) at normal engine RPMs as you can see from the graphic below that compares Nations 12-volt alternator with their 48-volt version. That’s nearly double what you would get from the “standard” DC-DC charger setup charging from your vehicle alternator with either the EcoFlow or the Victron setup. By the way, the general guideline for charging from your vehicle alternator is to limit the charging current to less than 50% of the alternator’s rating – for instance, if the alternator is rated for 220 amps, you’d want to limit the DC-DC alternator charging to around 100 amps. This is to prevent the early demise of your alternator. So, a secondary alternator is like having a generator running anytime you’re driving at the cost of a small impact on your fuel efficiency – something similar to other belt-driven stuff in your engine like an AC. Importantly, if you price out our Victron-based secondary alternator power system bundle, at today’s pricing, it’s about $2,800 more than the internal BMS bundle we’re using for the price comparison in this post. This is primarily due to the premium Victron batteries and the accompanying external BMS (Lynx Smart BMS) PLUS the actual Nations alternator kit and Wakespeed regulator. On the EcoFlow Power Kits, it’s possible to wire additional alternators/output to “solar input 2” or “solar input 3” but those are limited to 30 amps each and only the first input (labeled for alternator charging) can have its input current adjusted in the app. Using all 3x inputs on the EcoFlow kit would yield around 120 amps or around 1600 watts at 12-volts. Of course, using all the solar inputs for DC charging would prevent you from having solar charging. If you happen to have higher voltage chargers, maybe the power could be increased up to 1600 watts per input at higher voltages since the inputs allow 13-60 volts. If this sounds complicated, we agree! It certainly starts to erode that easy-to-use simplicity of the EcoFlow system. So, what’s the issue with wiring up a Nations alternator to an EcoFlow Power Kit? Basically, there is no point/benefit! It’s an expensive, 280 amp alternator paired with a Wakespeed regulator that outputs over 200 amps at most RPMs but the EcoFlow Power Kit “inputs” are limited to 60 or 30 amps. So, you could, technically, configure the Wakespeed regulator as if it were charging a standard 12-volt lithium battery and limit the maximum charging current to 60 amps but it’s considerably cheaper and easier to just pull 60 amps from your vehicle batttery/alternator! Limiting the current output of a high-current alternator seems silly indeed. And, even if you were willing to forfeit solar charging, we don’t know of a way that we’re aware of to “split” the Nations alternator output across the 1x, 60 amp, and 2x, 30 amp inputs while respecting those current limitations to each port and what would happen if it didn’t work exactly right? Would your entire Power Hub be destroyed? There are other, even more technical issues such as what kind of charge profile would you configure on a Wakespeed regulator for something that is actually a DC-DC charger input and not a battery? Would it have to behave as if it’s in “bulk” phase always so that there is never a current drop? Here again, the Victron system that seems complicated on the surface is, in reality, a lot easier and massively more reliable in this context. We’ve done the work to figure it all out and published it on our blog. We’ve also installed many of these systems and have high confidence in them. As far as cost, our Victron/Nations/Wakespeed secondary alternator bundle with a lot more battery storage (8,712 kWh vs 5,120) and all the benefits of a proper secondary alternator system is “only” about $1,000 more expensive. Cost Comparison Keeping in mind, that we’re not comparing apples to apples. Well, maybe we’re comparing different kinds of apples? Anyway, fruit aside, we tried to come up with a comparable system using high-quality, value-priced batteries like 280Ah SOK batteries and a bunch of Victron Energy equipment. The best way to do this is through one of our many best price bundles where we can offer you the very best pricing and help you gather up compatible components. And, unlike buying from Amazon or elsewhere, we are here to help you through your installation journey. Trust us, many people learn the hard way that Alexa isn’t very helpful when it comes to electrical system troubleshooting. 1) Start with a Best Price Bundle for Primary ComponentsSo, we started with our “internal BMS bundle” which simply means that the batteries have a Battery Management System (BMS) integrated into each battery (internal). In some cases, externalizing the BMS which is then shared by ALL the batteries in your system makes sense. For instance, a secondary alternator system where the charging rates are massive. Here’s a video of how we configured it: By the way, we have free example wiring diagrams that pair up with all our best price bundles to help guide you, or a professional installer. We refer to them as example wiring diagrams quite intentionally. There are so many ways to accomplish the same thing, safely and effectively that there is no single way to approach a power system. However, they are a great, totally free, starting point. 2) Accessory BundleThe “best price bundles” are designed to get you the primary components needed but not things like shore power inlets, load centers, fusing, wires, etc. While the primary components tend to be pretty aligned by “architecture” (internal BMS vs. external, etc.), these “accessories” are more universal and vary much more based on the nature of your system and particular installation requirements. Thus, we cooked up an “accessory bundle” (welcome to better names, please help!). So, step two for our price comparison was to configure the “accessory bundle” to follow the example wiring diagram for our internal BMS bundle. Here’s a video of that configuration. 3) Fiddly BitsBetween these two bundles, you’ll have everything you need outside of the “expendables” like lugs, heat shrink, wire management, a few beers, etc. For that, we have this spreadsheet for some recommended stuff that is frankly, too small and fiddly to be in our store. TotalsThe total for those two bundles, at the time we’re writing this post is $5,281. You’re probably going to need about $100 in “fiddly bits” (lugs, heat shrink, wire management, etc.). So, let’s round the grand total up to $5,400. Lower Pricing for Victron Energy EquipmentOne pretty incredible thing to be aware of is that, at the time of this writing (early 2024), Victron Energy has had two consecutive quarterly price reductions across their product catalog. Yes, you read that right… their pricing went down – twice – in six months! Every single other vendor in our store has either held steady or increased prices. But, Victron is a special company that manages their supply chain incredibly well and has decided to pass on the savings they’ve earned with their efficiencies to their customers. Bottom Line on CostThe 5kWh EcoFlow “Independence” Power Kit, at the time of this writing, is selling for around $7,300. So, the Victron-based system would be about $1,900 less expensive which, as we point out earlier, is very likely enough to hire an experienced professional installer to wire up your Victron system to overcome the limitations of the EcoFlow in this post. You’ll also benefit from an additional 2,272 kWh (172Ah) of battery storage with the Victron system which is pretty substantial. What About the Future We fully expect the EcoFlow products to get better over time and we’ll certainly be keeping an eye on them. You never know, perhaps we’ll rekindle the flame one day assuming this honest hot-take doesn’t burn any bridges. We hope not! We’re always looking for the most awesome stuff for camper vans and RVs. So, if new stuff comes to light, we’ll keep ya posted. Interested in 48-Volt Power Systems If so, check out this blog post that details a Victron Energy-based 48-volt secondary alternator electrical system that is truly massive!
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Tips for Wiring the AC Terminals on a Victron Energy MultiPlus II
We get a lot of questions from our customers about this, so we’ve made a short video with some basic tips on how to wire up the 120-volt AC terminals (AC input 1, AC output 1) on a Victron Energy MultiPlus II inverter/charger including using ferrules and to NOT use the release button when inserting the wires! Ferrules are inexpensive and help out with most electrical installations. One great place to source them is Ferrules Direct. Here’s a link to the particular ferrules we recommend for the 6 AWG AC out 1 terminals. You would use the 10 AWG gauge version on the AC input terminals. We also have some other recommended tools and terminals you might need in this document.
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48-Volt Secondary Alternator Power System - Massive!
Build Your Own Electrical System Bundle We worked extensively with Victron Energy and Wakespeed to design a system that will work reliably and safely! However, electrical systems are complicated and we recommend that you either have your system installed by a professional or, if you do it yourself, have it inspected by a professional when it’s completed. Please use the information provided at your own risk. Follow this link to gain access to our library of FREE Camper Van Electrical System Wiring Diagrams. Use the PDF files to print/zoom in. After following the link, open the Vanlife Outfitters 48V Secondary Alternator Wiring Diagram for our example wiring corresponding with this blog post. In this blog post, we dive into a massive, 48-volt secondary alternator power system for mobile applications like a camper van or RV using the Nations 48-volt alternator kit, paired with a Wakespeed WS500 regulator and a bunch of Victron Energy components. You can buy all the components necessary in one best price bundle in our store. Update February 2024. We wrapped up the installation before our Peace Love & Vans event in early February 2024 (the one with the epic weather!). The system performed even better than our expectations producing over 5,000 watts of power and sometimes over 6,000 watts at typical “driving RPMS. Also, as expected, it doesn’t do anything at idle. So, this is a system that is amazing for anyone doing some driving – even if it’s just short distances between your campsite and sightseeing/grocery shopping! If you’re planning on using at idle, you should consider the “high idle kits” we discuss in the post! Jump down the results video and installation photos. Update January 2025. Victron has released their NG (new generation) Smart Lithium Batteries including a native 48-volt battery (51.2 nominal voltage). As a result, we’ve slightly redesigned this system to use those batteries instead of using 2x 24-volt batteries in series. The NG batteries have a bunch of new features you can learn about in this video. Please us the diagram link above or for the updated system example wiring diagram. If you’re looking for the older examples you can use the following for the 2-battery and the 4-battery example diagrams. We put a lot of time into developing, testing, and documenting these systems. The resources are all free but we can only afford to do this because folks support our store! A few years ago we introduced our 12-volt secondary alternator power system, along with all the same kind of resources that made installing an advanced power system like that accessible to tons of our customers. Why a Secondary Alternator? Instead of huge battery banks, we like to focus on huge charging sources and “balancing” our battery bank size with the ability to get it recharged on a regular basis. We see a lot of customers with massive battery banks (think 1,000 amp hours or more) but try to rely on relatively tiny charging sources such as solar and DC-DC chargers. DC-DC charging is generally limited to about 50% of your vehicle’s factory alternator and solar is primarily limited by the small available space on a van roof – particularly when you have other things up there like Maxxfans or air conditioners. It just makes sense that, as you increase your battery storage capacity, you need to increase your charging capabilities. That’s where the secondary alternator comes in. These secondary alternators are designed specifically for high current charging, including external regulation from a device like the Wakespeed WS500 Pro for advanced charging in a way that keeps your batteries happy. That last point is pretty important since your batteries are one of the most expensive parts of your electrical system! The combo of the alternator and regulator is much like having a pretty big generator that is powered by your engine when you drive. It does put a load on the engine but it’s similar to other belt-driven stuff like your van’s air conditioner. Va Va Voltage – 12 vs. 24 vs. 48 Big picture, I think that most people should just stick with 12-volts unless they really need the benefits of a higher voltage system. 12-volts is very reliable and simple considering most “loads” running off a system are 12-volt or powered by an inverter supplying 120 volt AC. Our thoughts on 24 Volt systems have changed over time. You can read about why a 24 Volt system with secondary alternator or 24 Volt system (without secondary alternator) may be right for you. For those looking for massive alternator-based charging power, we still believe that a 48 Volt system is the best option. Take a look at the graphics below that compare Nations 12-volt, 280 amp alternator with the 24-volt, 140 amp alternator and the 48-volt, 100 amp alternator. The 48-volt alternator output is considerably higher which is one of the main reasons to consider a higher voltage system. At higher RPMs, it can produce about 70% more watts than the 12-volt alternator as you can see in the graphics below. So, if you need it, the jump from something like 3000 watts to something like 5000 watts of charging may be compelling enough to pay more for and deal with the extra complexity and other caveats (detailed below). In addition, the other advantages of a 24-volt system, like smaller wires, higher efficiency, and less heat are doubled with a 48-volt system. Native 48-Volt Loads – Air Conditioner Another advantage of a 48-volt system is the ability to run loads that are native to 48-volts like the impressive Nomadic Cooling X3 unit that we’ll be putting into our 48-volt test vehicle. Stay tuned for more blogs and videos about that! It’s the most powerful DC unit on the market and also very quiet and energy efficient – particularly compared to older, 120-volt AC rooftop options. The Benefit: Super Fast RechargingAs an example, let’s say you’re camping off-grid down here in Florida in the summer so you run your 48-volt air conditioner all night long and maybe have a fan running plus your refrigerator and other smaller loads. You might wake up in the morning, take a look at your Touch 50 screen connected to your Cerbo device, and see that the battery state of charge (SOC) of your batteries might be 60% or maybe even 50% meaning you’ve used something like 80 or 100 amp hours of stored power from your battery bank. Keep in mind that in this in this hypothetical story, you using one of the highest draw appliances – air conditioning – in a sort of worst-case scenario of Florida in the summertime. In other scenarios, you might use far less. With this 48-volt secondary alternator system, charging at around 100 amps, you would only need to drive for about 45 minutes to completely restore the power you used! Take a little drive to get some groceries. Maybe a little less if it was a sunny day and your solar panels were pitching in. Incidentally, if you use one of our Isotemp water heaters, connected to your van’s coolant lines, you’d also produce hot water for the next day or so with no additional power use. You see, we like the make use of the vehicle we’re driving around anyway! Let’s contrast that to using “just” the solar panels. In pretty much perfect conditions, the 4x, 200-watt solar panels shown in our example wiring diagram for this system might produce something like 12-14 amps so you’re looking at over 6 hours of sitting in the sun to accomplish the same thing as the grocery run and there are plenty of times you either don’t have sun or don’t want to park in it! Also, it can be quite difficult to fit so many panels on a roof of a van if you also want Maxxfans, air conditioning, etc. Surprising Cost ComparisonAt the time we’re publishing this blog post (prices change, y’all), the best price product bundle for our example 48-volt power system with 200 amp hours of battery storage at a nominal 51.2 volts (10,240 watt hours) configured with the 150/35 charge controller is “only” about $1,500 more expensive than the equivalent (same battery storage) 12-volt secondary alternator system. Caveats and Safety Currently, 48-volt alternators – of all makes/brands – have lower charging output at idle compared to their 12/24-volt counterparts. I’m sure this is being worked on and hopefully, it will improve over time but, for now, this isn’t ideal. 48-volts is high voltage and, as such, requires a lot more skill and care to be installed correctly for a safe system. If you’re going to install a 48-volt system you really need to know what you’re doing because the consequences of mistakes are much higher than a 12-volt system. In particular, “load dumps” can be catastrophic in a 48-volt system. A load dump is when the alternator is charging and there is a sudden, unplanned disconnect between the charging output and the batteries absorbing the current such as a short circuit, blown fuse, or a disconnect switch being turned off thus causing a voltage spike. High-quality 12/24-volt charging alternators, like the ones from Nations, have “avalanche diodes” that are designed to suppress the voltage spikes to something like 32 volts which, while high, isn’t likely to destroy your system components. However, 48-volt alternators don’t have this feature which means that a load dump can result in a 400+ volt spike which is extremely dangerous and will certainly destroy your system. Super duper bad. It’s much harder to find components that are rated for 48-volt systems – so many of the things that are normally used in 12-volt systems have a max rating of 32-volts or even 48-volts. In our 48-volt system, we’re going to see the battery bank voltage somewhere between 51 and 57-volts depending on the state of charge. We’ve made this easier for our customers. In our example system (see wiring diagram at the top of this page), all the components are rated for 58-volts or higher. Also, we have an entire section of our store that is now dedicated to this higher voltage world of 48! A 48-volt power system allows you to really scale up your solar system if you have the space for it (let’s say on a skoolie build with a large roof) since the current produced at the same wattage is much lower. But, you also need to be sure that your solar panel array(s) are running at high enough voltage to charge the batteries. Victron Energy solar charge controllers require that the input voltage from your panels (PV input voltage) is at least 5 volts higher than the battery bank voltage. Most solar panels we see our customers output something around 20 volts in optimal conditions and less in suboptimal conditions (cloudy, dusk, dirty panels, etc.). Therefore in a 12-volt system, it’s pretty easy to have the PV input voltage above the battery voltage. In a 48-volt system, you’ll need to be sure to wire enough panels in series (or series, parallel) to get the input voltage up to at least 5 volts greater than the battery voltage. Aiming for the higher end of the solar controller rating is a good idea so that you get some charging from solar, even in suboptimal conditions. In our example system, we show 2x sets of 2x panels in series that are then wired in parallel for something around 110-113 volts coming into the Victron Energy 150/35 solar charge controller. System Overview If you download the wiring diagram as a PDF (link at top of the post), you can zoom in/out to see all the details presented there. In addition to the Nations/Wakespeed combo, this example system is full of brilliant blue boxes from Victron Energy! We offer the system with 2x (or more) Victron 100 amp hour, 48-volt (51.2 nominal voltage) Smart Lithium NG batteries wired in parallel using the Victron Lynx Class-T Power In (M10). That is roughly equivalent to an 800 amp hour battery bank at 12-volts. These are “external-BMS” batteries which means that the Battery Management System is not inside each battery like many lithium batteries such as Battleborn or SOK, etc. Instead, this system uses the Lynx Smart BMS NG for both batteries (or more if you were to add additional in the future). The Lynx Smart BMS is a combination of a BMS, a system-wide battery monitoring shunt/monitor, and a giant disconnect switch (more on that later) that is integrated into the Lynx system from Victron including the single Lynx Distributor (M10) we have in this system. You can read more about internal vs. external BMS batteries in this post. The rest of the system is fairly typical for a van/RV/mobile power system (MultiPlus inverter/charger, solar controller, etc.) except that things are running at 48-volt instead of a more traditional 12-volt. We also need a pair of Orion 48/12/30 DC-DC converters running in parallel to convert the 48-volts DC to 12-volts DC to supply power to all the normal 12-volt stuff (lights, refrigerator, etc.). Battery Notes The example system and best price product bundle use 2x (or more) Victron 100 amp hour, 48-volt (51.2 nominal voltage) Smart Lithium NG batteries. When it comes to batteries, most people are pretty focused and familiar with two key specifications: voltage (48-volts in this case) and the storage capacity, typically expressed in amp hours (100Ah per battery in this case resulting in 200+ amp hours when wired into a bank in parallel). The other key specifications are the “recommended charge current” (≤100A for these batteries) and the “recommended discharge current” (≤100 amps for these batteries). Those last two are basically how quickly you can refill the batteries when charging or how quickly you can discharge them for your loads. If your chargers or loads are higher than those ratings, you can damage the batteries or create excessive heat. External BMS batteries like these typically have much better specifications since, often, an internal BMS is the limiting factor. You can see all the specifications of the batteries here. So, if there is any limitation at all in the example system, which is a strange thing to write in the context of this massive beast of a power system, it’s that you might find yourself in a rare and unusual situation where the combination of your off-grid charging sources (secondary alternator and solar) may actually exceed the recommended charge current rating of the battery bank. In the example system (with two batteries), this is 200 amps (100 amps per battery) which at the nominal voltage of 51.2 volts is 10,240 watts! So, that’s a lot of juice for being a “limitation”. Another great feature of this system is that it will automatically coordinate the maximum allowed charging current across all the charging sources using something called DVCC (Distributed Voltage and Current Control). This is possible because every charger in this system has digital connectivity to the Cerbo GX (Wakespeed regulating the Nations alternator via VE.Can, solar charge controller via VE.Direct and the MultiPlus inverter/charger via VE.Bus) and the Cerbo GX is communicating with the BMS and its current monitoring shunt via VE.Can as well. In the Cerbo GX we can set a “maximum charge current” and have it intelligently manage this for us. So, in those “perfect” conditions you’re going to keep the batteries happy but in some cases, forfeit some of potential power available at that moment by throttling down one or more charging source. Below is this setting in the Cerbo GX (Menu -> Settings -> DVCC). Since you have plenty of “headroom” on the maximum charge current, it’s even possible to charge from the standard, vehicle alternator with this 12-volt to 48-volt battery to battery (DC-DC charger) from Sterling Power that could be added to the system so that you could charge from BOTH your Nations secondary alternator as well as your factory vehicle/alternator or use that unit as a sort of backup. Victron recommends that you update the firmware of new batteries (using VictronConnect and Bluetooth) and pre-charge your batteries individually before wiring them up into a system. Full details in the manual. And, if you’re wondering, you don’t feel like you’re getting shocked if you touch the 48-volt terminals of the battery. Here I am demonstrating this and I feel fine 🙂 But, Where Is The Main Disconnect? Missing the bulky red disconnect/battery switch you’re probably used to seeing bolted onto a Lynx Distributor? This system uses the Victron Energy Lynx Smart BMS NG which has one of those massive switches built into it. It’s a 500 amp rated “contactor” that can open or close to act as a switch being “on” or “off” respectively. As the name suggests, it’s also the BMS (Battery Management System) for our Victron Smart Batteries so, if the batteries are distressed (too hot, too cold, over or under voltage), they can trigger this contactor to “open” which will electrically disconnect all the “loads and chargers” connected downstream from the Lynx Smart BMS electrically. Finally, there is also a battery monitoring shunt inside the Lynx Smart BMS that communicates with the Cerbo GX to show the same kind of battery status information that the popular BMV-712 does. All this in one single box! But that’s not all! If you look closely at the example wiring diagram, you’ll see that we have a toggle switch wired into the “remote” terminals on the Lynx Smart BMS. This allows you to open/close the contactor (turn off/on the system) with that switch in the same way you would a big, bulky main disconnect switch with one HUGE advantage. Anytime the contactor in the Lynx Smart BMS is about to open – whether triggered by the batteries to protect themselves – or by you manually – the BMS will communicate this to the Wakespeed WS500 regulator before this happens so that the alternator can stop producing charging current thus preventing an extremely dangerous voltage spike that would occur if someone flipped off a manual disconnect switch while the alternator was charging! More about so-called “load dumps” earlier in this post. Field Drive in 48-Volt Alternator Systems First, what is the field drive? It’s the wire that supplies voltage to the alternator’s rotating field coil. In this example system, it’s the blue wire on the Wakespeed wiring harness “alternator leg”. You can think of the field drive as the sort of gas pedal – the more field voltage, the more current the alternator will produce. If you want to dive deeper into how alternators work, this is a pretty good video. We often get asked if you can install a secondary alternator onto an engine before you finish the rest of the electrical system and wire it up to that system. The answer is yes! Even though the alternator will be spinning after the mechanical installation, it won’t be producing any current until the Wakespeed regulator gets installed and provides the field voltage to the alternator. In 12-volt and 24-volt systems it’s common for the “field” to be specified to operate at the same voltage as the connected battery. This is not always the case with 48-volt alternators. In fact, many 48-volt alternators, the field is actually specified at 12-volt. In such cases, there are a couple of ways the Wakespeed WS500 can be deployed. This is what we recommend… Apply a derate value using the $SCA command when configuring your Wakespeed. The $SCA command has three ‘”derate” values which can be set to “normal”, “small alt”, and “half-power”. These are typically used to reduce the output of an alternator to account for system cooling concerns and prevent overheating and/or to reduce the load on the driving engine. But they can also be used to effectively reduce the “field voltage” from 48-volt to allow direct driving of a 12-volt field alternator even when the red, power supply wire on the Wakespeed harness (ALT+) is attached to a 48-volt battery system. To do this simply start with a “normal’ derate value of 0.25 (25%) which will reduce the average field voltage to an acceptable operation range. Due to the prevalence of 12-volt fields in 48-volt alternators, beginning with version 2.5.0 of the Wakespeed firmware, it will default to this 25% derate values if those have not been explicitly defined using the $SCO command detailed above. If your alternator has a true 48-volt field (the Nations alternator we show in this example system uses a 12-volt field), you will want to explicitly issue a $SCO command to restore the 100% field drive (r max field drive is otherwise appropriate). Connect the red, power supply wire on the Wakespeed harness (ALT+) to a 12-volt source such as the vehicle battery. Importantly, if you take this approach, you need to be sure to wire the red/yellow wire (VBAT+) from the Wakespeed harness to the 48-volt battery for proper voltage sensing. This does not work with the “van harness” which is a simplified version of the “standard” Wakespeed harness that does not include the VBAT+ wire. Circuit Protection In our example wiring diagram (zoom in on the PDF), we’re using the Lynx Smart BMS with a Lynx Distributor downstream as the main bus bar. From left to right, we show the following connections and fusing: 125A (80V) mega fuse for the Nations alternator charging output 125A (80V) mega fuse for the MultiPlus inverter/charger 80A (80V) mega fuse to feed the Littelfuse secondary bus bar that accepts lower current rated, MIDI fuses (see below) 60A (80V) mega fuse for the charging output of the solar charge controller. Note that this fuse size is larger than it needs to be (max of 35 amps from the charge controller multiplied by 1.25 (25% additional) is around 44 amps. However, the 10 AWG wire we show can accept 60 amps at 48-volts, so we can have this additional headroom. Remember that circuit protection is to ensure your wires are not exceeding their maximum ampacity. The example wiring diagram uses a very compact, Littelfuse bus bar with MIDI fuses. as a secondary bus bar. It’s kind of like a miniature Lynx Distributor in the sense that it combines a bus bar with fusing. However, it does not have a negative bus bar so any required negative wiring is run to the main bus bar (Lynx Distributor). Ideally, you keep your wire lengths for the positive and negative wires close to the same lengths. There are the following three connection points inside the secondary bus bar. 30A (58V) MIDI fuse for one of the two Orion 48/12/30 converters. Similar to the 60 amp fuse above, this is larger than the load requires but the lowest amp-rated MIDI fuse from Victron. The Orions will pull about 6-8 amps to create the 360 watts at 12 volts. But, here again, the 10 AWG wire is more than capable of carrying up to 60 amps if there was something like a short circuit. 30A (58V) MIDI fuse for the second of the two Orion 48/12/30 converters 50A (58V) MIDI fuse for an additional 48-volt appliance such as an air conditioner. In our example, we’d be using a Nomadic Cooling X3 which calls for a 50 amp fuse (see specifications chart). Configuration With everything wired up, let’s dive into configuring the system! Given the nature of this post, we’re only going to focus on the configuration steps for enabling the secondary alternator and Wakespeed regulator. One awesome feature of this system provided with the Lynx Smart BMS is that the charge profile for the other Victron Energy chargers in our example system (MultiPlus inverter/charger and solar charge controller) is managed intelligently by the Cerbo GX using DVCC. This is possible because all of these devices are “talking” to each other digitally through the Cerbo GX. If you want to learn more about this DVCC magic you can read this section of the Cerbo GX manual. One benefit of this is that it’s quite easy to configure the system for charging. But, If your system has other chargers/devices that don’t have a data connection on them (no VE.Bus, VE.Direct, VE.Can, etc.), such as an older (pre-Orion XS) Orion DC-DC charger, and therefore cannot be managed by DVCC, you’ll have to configure that device the “old fashioned” way with VictronConnect which is beyond the scope of this post. We also won’t discuss all the setup possibilities of the Cerbo GX – you can check out this other post about that. Instead, we’ll only focus on what’s necessary to make it work with the Wakespeed regulator. However, we’ll be dedicating another post to the Cerbo GX including connecting it to VRM so “stay tuned” for that, or consider signing up for our email newsletter which is available at the bottom of all of our pages. Victron Lynx Smart BMS Configuration with Victron ConnectRemember that any Victron product with the word Smart in the name means that you can configure, monitor, and control it via Bluetooth using the VictronConnect app. So, if you haven’t done so already, you’ll want to install VictronConnect. Links to download the app are available for iOS, Android, Windows, or MacOS on the VictronConnect page. Most folks find the app simple to use but you can read through the manual if you need it. To use it, you’ll need Bluetooth enabled on your mobile device or computer so that it can communicate with the various Victron products. Once you open the app, you’ll see a list of all the Victron products that are within Bluetooth range -all with their factory default names. You can easily rename each device to make it unique to your install if you’d like. To configure (or monitor/control) a device simply click on its name from the list in VictronConnect. The first time you connect you’ll be asked to pair with that device. The default pairing PIN is 000000. We recommend you change the PIN on all your devices so that other users of VictronConnect don’t mess with your system! Keep in mind that if you find yourself in a place with other camper vans/RVs that have Victron components you might see a bunch of other devices listed in VictronConnect – basically anything that’s within Bluetooth range. By the way, if you don’t have any of this equipment yet but are curious how it all works, you can actually use VictronConnect with “virtual” (demo) devices. In other words, you can go through the settings and screens available in VictronConnect for any Victron Smart product by using the demo library available in VictronConnect. This is a great feature to use when planning a system. Let’s start with the Lynx Smart BMS NG. Connect to this device in VictronConnect. The first screen you’ll see is the “status” tab that displays the same kind of information as other battery monitors from Victron including the calculated state of charge (SOC) as a percentage and if you scroll down, a bunch of other information about the battery including voltage, current, etc. Below is a screenshot of this screen. Since the Lynx BMS is configured for 12-volt batteries by default, the first thing you’ll notice is an error reading “battery voltage not allowed”. You are likely to be prompted for a firmware update as well. If so, proceed with that firmware upgrade. Next, enter the settings of the Lynx Smart BMS NG by tapping on the “gear icon” in the very top right part of the screen. Here you’ll want to change the system voltage to 48 and tell the BMS about your batteries. In our base system with the 2x, 100Ah batteries in parallel you would enter 2x for batteries and 200 amp hours for campacity. You’ll also want to change the “relay mode” setting to “alternator ATC”. This is how the “white wire” (feature in wire) that we wired from the Wakespeed harness into terminal #9 on the multi-connector of the Lynx SmartBMS is interpreted by the BMS. It enables the ATC (allow to charge) relay to disable charging from the Wakespeed/Nations if the battery triggers that state. Note: if you’ve ever configured another Victron Energy battery monitor such as the BMV-712 or SmartShunt you may notice that the settings presented here are different and, in some ways, more simple than you’d see on the other products. That’s because, in this example system, you can literally only use one single type of battery – a Victron Smart lithium battery. The batteries may have different capacities (200 vs. 300Ah, etc.) but they are the same baseline so many of the settings about the battery that you have to change/set in other systems are already known/assumed in this case. Wakespeed WS500 ConfigurationIf you buy your Wakespeed regulator from us as part of our best price product bundle for this system it will ship pre-configured based on the information we collect when you add the stuff to your cart. However, configuring a Wakespeed WS500 regulator is pretty simple when using the Wakespeed Android app – particularly with the latest Wakespeed Pro that we stock that has a Bluetooth connection. Configuring the Orion 48/12/30 DC-DC ConvertersThese are the devices that convert the 48-volt system voltage to 12-volts for your main DC load center for your common 12-volt stuff like lights, fans, appliances, etc. They are not “Smart” so there is no Bluetooth connection for configuration/monitoring. But they’re quite simple devices. All you’re going to do with these is get a tiny screwdriver and turn the potentiometer (how often do you get to use that word!) to adjust the output voltage (-15% to +25% of the default output voltage). Turn counterclockwise to decrease the output voltage. Turn clockwise to increase the output voltage. In our system, we’re setting this to right around 13.5 volts which is a typical “float voltage” in a 12-volt system. Charts! Nations Alternator Charging Output Comparisons (12V / 24 / 48V)Click On Images To Open Larger Other Recommend Reading/Resources This video details every connection on the Wakespeed WS500 van harness. There is a lot of relevant additional information in our blog post about the 12-volt version of this system that we didn’t want to repeat here. We’ve always used the Blue Sea Circuit Wizard for sizing wires in 12-volts but it doesn’t work for 48-volt systems. However, we found this 48-volt wire size calculator to be very useful. There are quite a few configuration options. Blog post about configuring a Cerbo GX and Lynx Shunt for battery monitoring. If you have a Sprinter and want to remotely start it at a specified battery state of charge (SOC) and/or have it idle up to produce more RPMs/alternator charging current check out this kit from Mid City Engineering. A quick note on Mercedes Sprinter N62 bracket: The general consensus (Nations, our installers, reports from the internet) is that the 3-belt system that is used by Nations in their kits for Sprinters without the N62 “factory secondary alternator bracket” are better than the N62 version. In fact, we’ve heard of reports from Nations that some people who paid at the dealership for the N62 bracket have taken it off in favor of the 3-belt option. Installation Photos and Testing Results Note, these tests were were done with the older/original configuration of this system using 2x, 24-volt batteries wired in series as we detail at the beginning of this blog post. However, what we’re testing is really the performance of the Nations alternator with the Wakespeed regulator which will be the same with the newer, 48-volt Smart Lithium NG batteries.
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Configuring a Victron Cerbo GX, BMV-712 or SmartShunt and Connecting with VRM
This post was originally published in 2023. We think that the content in this blog is still useful, but some things have changed just a little bit: new GUI, new features, same great powerful capability! Check out our refreshed blogs like Setting up Victron's Remote Monitoring, and inviting Vanlife Outfitters to your system and Configuring your Victron system with VRM for a updated take on these important features. This post details how we suggest you configure a Victron Cerbo GX for a camper van/RV and, once you’ve done so, how to connect it to Victron’s free remote monitoring and control cloud service called VRM. This guide assumes that you have a MultiPlus inverter/charger as we show in our free example wiring diagrams. While you’re here, you might also be interested in our blog post about how to monitor water tanks with a Cerbo GX or how to wire up a cooling fan that is turned on automatically using one of the Cerbo GX’s relays and a clever 4-in-one Ruuvitag sensor (temperature, humidity, air pressure, and motion). Cerbo GX VersionsFor a period in 2024 Victron was offering three versions of the Cerbo GX as we detailed in this video (Cerbo GX, Cerbo-S GX and the MK2 model). As of 2025, Victron eliminated the Cerbo GX and the Cerbo-S GX so that there will, once again, be only one single model which is the MK2 version. In other words. the Cerbo GX MK2 replaces the original Cerbo GX and the Cerbo-S GX is no longer available. Victron Energy also offers the Ekrano GX which is similar but has an integrated touch screen. For the sake of simplicity, we’ll refer to all “GX Devices” (all versions of the Cerbo) as the “Cerbo GX” in this post since they all use the same underlying operating system (VenusOS). Cerbo GX Configuration 1. Connect a Touch Screen The primary, in-person monitoring and control interface to the Cerbo GX is either the 5″ Touch 50 screen or the 7″ Touch 70 screen. These touchscreens can be powered from any 12-volt USB plug – either one like this in your rig, or the USB port that is right next to the HDMI port on the Cerbo GX itself. The video and touch commands/data require an HDMI connection. If you are placing your touchscreen far away from the Cerbo GX we’ve found this 25′ HDML extension cable paired with a HDMI female-to-female adapter works well. 2. Power on the Cerbo GX You do this by plugging in its DC power supply cable into the bottom of the unit and making sure the other side of the wire is wired up to your DC positive and negative bus bars/battery terminals. There is an integrated, inline fuse on the DC positive wire that is supplied with the Cerbo GX. Once power has been applied, it will take a minute or two to boot up but you should see some of the LED lights on the Cerbo GX turn on and the touchscreen coming on during the booting process – first with the Victron Energy logo and later with one of the standard screens (pages). 3. Connect the Cerbo GX to a Wi-Fi Network Tap on the lower right portion of the touchscreen to open the menu bar to access the Menu. Then choose “Settings”, then choose “Wi-Fi” and then “Wi-Fi networks”. This should open a list of available Wi-Fi networks much like any computer or mobile device. Next select the network name you wish to connect to and finally, press on the empty “field” area on the right side of the password row. This will open a virtual keyboard allowing you to enter the password for the Wi-Fi network. After you enter the password and return to that network’s screen, you should see that the “State” row reads “Connected”. If it doesn’t, it’s likely you need to re-enter the password. 4. Update the Firmware One of the great things about Victron Energy equipment is that their developers are continually improving the apps and firmware which means you get extra features and stability every time you update the firmware or apps. To update the firmware (the version of Venus OS running the Cerbo GX), open the Menu, choose Settings, and then Firmware. From this screen you want to make sure that “Check and update” is selected on the “Auto update” row and then press the “Press to check” button. From there you’ll either be guided through the update or it will report that you already have the latest version. 5. Customize System Name Open the Menu, choose “Settings” and then choose “System setup”. Take a look at the first two rows on this screen. The “System name” should be set to “User defined”. You can then press on the empty field area in the “User defined name” row and enter what you want to name your system. 6. Label AC Input 1 We like to choose the appropriate “label” for the AC Input 1 on the MultiPlus inverter charger. In most cases this input is fed from Shore power. From the same “System setup menu” (Menu -> Settings -> System Setup) press on the AC Input 1 row and choose “Shore power”. 7. Enable Remote Console One of the cool features of VRM (more on that below) is the ability to remotely control your Cerbo GX using the remote console. To enable this we need to update a few settings. Start by entering the Menu, choose “Settings” and then choose “VRM online portal”. Make a note of the “VRM Portal ID” from this screen. We’ll need that a little later when we connect the Cerbo GX to VRM. Then scroll down until you see the the “VRM two-way communication” option and turn it on. Now go back into Settings and choose “Remote Console”. We recommend pressing on the “Enable password check” and choosing a password that you will need to enter when using Remote Console from VRM. Then make sure that “Enable on VRM” is turned on. Finally, you need to power cycle/reboot your Cerbo GX before these settings take effect. One simple way to do this is to pull the power supply plug from the bottom of the Cerbo GX and then replug it. 8. Boat & Motorhome Overview & Units Open the Menu, choose “Display & language” and then turn on the “Show boat & motorhome overview”. This adds a new “page” or “screen” to your Cerbo GX that allows you to control a MultiPlus inverter state (on, off, inverter only, charger only) as well as the AC input current. Next, choose “Units” from the same “Display & language” menu and change to F from C (Fahrenheit). Settings -> Display & language -> Units -> set temp to F (From C – available in Venus OS 2.9+) 9. Enable DC System Open the Menu, choose “System setup”, scroll down to “Has DC system” and turn that on. What the heck is this? Basically, it just tells the Cerbo GX that there are DC loads in the system that you want to monitor – such as your DC load center/fuses. When turned on you see the DC “box” on the display screens/pages. In a van/RV, there is almost always a DC system but in some other applications, such as an off-grid install, there may not be any DC loads. 10. Set Time Open the Menu, choose “Settings” and then “Date & Time”. From that screen, press on “Date/Time local” to set your local time and then press on “Time zone” to select your local time zone. 11. Bluetooth Settings Open the Menu, choose “Settings” and then choose “Bluetooth”. From this screen, you’ll want to make sure that Bluetooth is turned on (“Enabled”) and then press on “Pincode” to set the login code to connect to the Cerbo GX via Bluetooth using VictronConnect. 12. Configure Your Battery Monitoring If You Have a Victron BMV-712 or SmartShuntYou need to tell the battery monitor about your batteries by connecting to the device via Bluetooth with the VictronConnect app. The default password/pincode for Victron Smart devices when connecting via Bluetooth is 000000 (six zeros). Once connected click on the “gear icon” in the very top right portion of the screen and then click on the “Battery” row to open the battery configuration screen. You should be able to find these specifications in the documentation from your battery manufacturer. For SOK batteries, check here. Battery Capacity: total amp hour rating of your battery bank Charged voltage: varies with battery & manufacturer - see datasheet Note that this number should be about .2 or .3 volts below the absorption charge voltage set in your charging devices Discharge Floor: 10% (or, more conservatively 20%) The discharge floor is used to calculate the “Time-to-Go” or “Time remaining” info on the battery monitor. Lithium batteries can be discharged completely but it’s not recommended to go below 10-20%. By setting this to 10% or 20% instead of 0%, the battery monitor will change its calculations to provide for this “reserve” power. This value is also for triggering the relay at a certain state of charge (SOC). Tail Current: varies with battery & manufacturer - see datasheet Charged Detection Time: 3m Note, this setting, along with the “Charged voltage” above is what triggers a “synchronization” to 100% state of charge. In other words, if your battery bank gets to the “Charged voltage” setting for 3 minutes, it will be considered fully charged by the battery monitor and, from that point, it will track actual power consumed from the batteries (amp hours) to calculate the state of charge. This algorithm gets better after a few charge/discharge cycles. Peukert Exponent: 1.05 Charge Efficiency Factor: 99% Current threshold: 0.10A Time to go averaging period 3m Battery SOC on reset: Keep SOC State of Charge: leave defaults Synchronize SOC to 100% button In normal operation you probably won’t use this feature. However, if you are certain your batteries are fully charged, but the normal charged detection mechanism isn’t working (a combination of the batteries reaching the “Charged voltage” setting for the length of time specified in the “Charged detection time” setting), you can press this button to manually “synchronize” to 100% state of charge. Zero Current Calibration button This option can be used to calibrate the zero reading if the battery monitor reads a non-zero current even when there is no load and the battery is not being charged. Note: most battery manufacturers recommend that you make sure your batteries are fully charged at least twice per month which allows the battery monitor to synchronize to keep the state of charge calculations. This video has some great information. If You Have a Lynx Smart or NG BMSIf you have the Lynx Smart or NG BMS, it means you’re using Victron's Smart or NG lithium batteries and, therefore, the system already knows almost everything it needs to about the batteries. You just need to connect to the Lynx Smart NG BMS via Bluetooth with the VictronConnect app. The default password/pincode for Victron Smart devices when connecting via Bluetooth is 000000 (six zeros). Once connected, click on the “gear icon” at the very top right part of the screen and change the 3x settings shown below in the “System settings” section. 13. Add Ruuvitag(s) Ruuvitags (available in 3x versions with varying levels of waterproof) are wireless (Bluetooth) sensors that can provide temperature, humidity and other data to your Cerbo GX. We like to use one inside our van, one outside of the van, another in the fridge, etc. The integrated Bluetooth connectivity on the Cerbo GX is not strong enough to support the Ruuvitag Pro so Victron recommends that you add a third-party USB to Bluetooth adapter. We’ve found this TP-Link model is affordable and works great. Once you’ve connected the USB Bluetooth dongle, pull the plastic tab from the Ruuvitag to activate the unit with its internal battery. Next, open the Menu on the touchscreen and go to “Setting” and then choose “I/O”. Make sure that the “Enable” switch on this screen is turned on. After a few seconds, you should see the Ruuvitag you have powered on appear in this menu. Once it does, turn on the switch next to that device as well. If you’re adding multiple Ruuvitags, we recommend that you do one at a time so that you can write down each Ruuvitags unique ID and make a note of “where” you’ll be placing that particular Ruuvitag. This will help you give the Ruuvitags meaningful names in the next step. Once you’ve added all the Ruuvitags you’ll be using you can rename them something meaningful. Start by reopening the Menu which will bring up the “Device List”. You should see each Ruuvitag listed here. To rename, press on the Ruuvitag you wish to name then press on “Device” and then press into the empty field in the “Name” row to bring up the virtual keyboard and type in the name you want to use. You might also be interested in our blog post about how to trigger a fan controlled by the Cerbo GX relay with at a particular temperature as measured by a Ruuvitag. 14. Consider Customizing the Logo on the Cerbo GX Screen This video details the process. In our experience, a 800 x 440 pixel image works well for aspect ratio/size. If you don’t get the aspect ratio right it squishes the logo. Also, we recommend using a background since transparent images don’t look good. 15. Consider Adding Tank Monitoring If your rig has water tanks – fresh or grey – you might want to check out our tank monitoring blog post to be able to monitor your tank levels on the Cerbo GX. 16. Consider Adding GPS You can add a USB GPS receiver such as this one to your Cerbo GX which is a really cool way of tracking the location of your van/rig. And, once you connect up your Cerbo GX with VRM (coming right up!) you can even configure a “geofence” area on a map and receive notifications if it goes outside of that area. Connecting your Cerbo GX to VRM 1. Create a VRM Account Start by establishing a VRM account for yourself on this page. These accounts are “free for life” from our friends at Victron! Once you register, they will send you a confirmation email that you have to open and confirm. Once you’ve confirmed, login to VRM. 2. Add Your “Installation” Next, navigate to the “Add installation” screen in VRM. Then choose “Cerbo GX or Cerbo S-GX” option. You’l need to enter the “Installation ID” which is the “VRM Portal ID” you may have written down back in “step 7” above. If not, refer to “step 7” to find this information on your Cerbo GX. You can also name your “installation” on this screen. Once you’ve provided that information you can press the “Request access” button to proceed to the next step. Note, if the Cerbo GX has previously been linked to another VRM account, and that “VRM Portal ID” and you try to “Request access” when establishing your new account/installation, the email address used the first time the Cerbo GX was added to VRM will be sent ane mail and you’ll see a message on the screen that reads “An email has been sent to the administrator adding new site”. The easiest thing to do is to have the original owner/account holder forward the email to you. If that isn’t possible you can reach out to your Victron dealer (which might be us!) so that we can try to manually override this for you. 3. Update Preferences In VRM, click on “Preferences” in the left-side navigation (if you don’t see “Preferences” you’re likely viewing an “installation” so you’ll have to click on the “back” button at the top of the left-side navigation first). Next, click on “Display preferences” and configure the options on this screen to your preferences. We normally change “Units” to Fahrenheit and Gallons. 4. Enable Widgets In addition to the main “Dashboard” report that shows much of the same information you’d see on the Touch 50 or Touch 70 screens, you can add a super wide range of “widgets” to the “Advanced” view in VRM. Widgets are basically domain/device-specific reports/charts. Below is a screenshot from the “Advanced” view in VRM showing 3x widgets. To enable these widgets start by navigating to your installation by finding its name in the left-side navigation in VRM. From there click on “Advanced”. New installations do not have any widgets activated so you won’t see much there yet. To choose which widgets you’d like to see, look for the “widgets button” near the top right part of the VRM interface. Below is a screenshot of this button. That will bring up a list of the various devices in your system such as the “Gateway” (your GX device – the Cerbo GX), battery monitors, solar charge controllers, Ruuvitags, etc. Basically, anything that is connected to the Cerbo GX. You can then click on a device to reveal a list of available widgets for that particular device. Below is a screenshot showing some of the widgets for a Victron SmartShunt which I have renamed “Battery Monitor – AW Battery Monitor”. You can see that there are 7 widgets available and many of them are colored blue which indicates that they are active/selected. To add/remove a widget from a device menu, simply click on its name once to activate (shown in blue text) and click again to reactive (black text). Widgets can be reordered to suit your preferences. Also, as you scroll through the data in one report, you’ll see the various reports are linked together. Many of the widgets/reports can be made larger by clicking on the “expand icon” in the top right portion of the widget. 5. Enable Inverter/Charger Control If you want to be able to change the “mode” of your inverter/charger (on, off, charger only mode, inverter only mode), go into your installation, navigate to “settings” and then “general” and toggle on the Inverter/Charger control as shown in the screenshot below. 6. Considering Sharing Access If you purchased your equipment from us (thanks), you can take advantage of our world-class support including adding us to your VRM account so that we can help you troubleshoot remotely when necessary. Or, perhaps you want someone else monitoring your system for other reasons. Whatever the reasons, to share your system, navigate to that “installation” in the left-side menu by clicking on the “installation”/system name. Then click on “Settings” and then select “Users”. From this screen, you can use the “Invite user” button to invite a user. If you want to invite us, at Vanlife Outfitters, please share with our service department email address which is service@vanlifeoutfitters.com. Victron also offers a "Share" link, but Vanlife Outfitters technical support can not use that method. Please use the Settings -> Users -> Invite User steps above to share access with support. 7. Consider Adding a Micro SD Card Anytime your Cerbo GX has an internet connection, it will push the date from the system to VRM but if you’re offline this isn’t possible. You can add a Micro SD card to the Cerbo GX (built in slot) so that all this data can be stored locally and, when you’re back online, it will upload the data captured during that period! Other Cool Stuff (for the Classic GUI only) If you want to really go big and see tons more information/data on your Touch 50/70 screen you can add something called GuiMods which is pretty cool. This video details the process. Note that the updated "New GUI" (really Victron, that's the best you could do for a name?) no longer supports GuiMods. The New GUI incorporates many of those powerful mods into the standard Venus OS release. Our recommendation is to make sure that the New GUI is running on your Cerbo. We think you'll like it!
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Video Tour of a Secondary Alternator Power System
An in-depth tour of an advanced Victron Energy power system we installed into a 2022 Sprinter van that features 4x charging methods. Dedicated Nations secondary alternator kit with the Wakespeed WS500 alternator (around 120-150 amps depending on RPMs) From the vehicle alternator with a Victron Orion DC-DC charger (30 amps) Solar charging with a Victron 100/30 MPPT charge controller Shore power charging up to 120 amps with the Victron MultiPlus II 12/3000/120 If you’re interested in this system, we have a detailed blog post about it including a FREE wiring diagram and we also offer a best price product bundle to get you all the parts at the best possible price! If you’re interested in higher voltage systems, check out our 48-volt secondary alternator blog post.
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Using a Ruuvitag to Trigger a Cooling Fan in your Electrical System with a Victron Cerbo GX
We often get asked about ventilation and fans to keep an electrical system cool under loads. After all these power system components can get pretty warm when running AND they’re very often tucked away under a bed or inside a cabinet. Also, if Victron Energy equipment gets too hot, they start “derating” which basically means that the ability of the device to perform at it’s highest performance is decreased in relation to the temperature. For instance, if you have a MultiPlus 12/3000/120 inverter/charger that is rated for about 2,400 watts at 77 degrees Fahrenheit, and if the temp goes up to 104 degrees, the output is “derated” to 2,200 watts. Below is a table taken from the spec sheet for the unit that illustrates this pretty clearly. Or, if you really want to nerd out, Victron has this white paper. Similar “derating” happens on other devices such as MPPT solar controllers or DC-DC chargers, etc. So, what to do for ventilation? The simple answer is to add as much “passive” ventilation as you can and try to have at least two vent locations to allow the air to flow through the area. There are lots of ways to add vents to cabinets that I don’t think we need to cover here! Anyway, there is an online store called Amazon.com (I know, weird name), that sells a variety of things including these circular vents that we’ve used often. But, practically speaking, sometimes, passive cooling just isn’t going to do the trick so we wanted to share how to add some “active cooling” with computer fans that only turn on when the temperature in your electrical system area reaches a particular temperature. To do this we’ll use a Ruuvitag (wireless, Bluetooth temp/humidity/air pressure sensor) and the built-in relay inside a Victron Energy Cerbo GX. Connecting a Ruuvitag To A Victron Cerbo GX Ruuvitags are small, affordable sensors that are incredibly easy to deploy since they can communicate wirelessly with a Victron Cerbo GX. They come in three versions. We’ll be discussing the baseline, 4-in-one Ruuvitag (temperature, humidity, air pressure, and motion). There is also a water-resistant 3-in-one version (temperature, humidity, and motion) as well as a fully waterproof (submersible) 2-in-one version (temperature and motion only). In our vans, we like to put these Ruuvitags in various places – one in the main living space, another near the power system, one outside, and sometimes one in the fridge too! Victron Energy recommends using a USB to Bluetooth “dongle” to increase the Bluetooth signal reach on the Cerbo GX. These are quite inexpensive (around $10) and make a big difference. We have a few recommended/tested options on the product page (in the description). To add a Ruuvitag to your system, start by pulling the plastic strip out from the side. This will turn the Ruuvitag on by allowing the battery to connect to the circuit board. Next, on the Cerbo GX, navigate to “menu -> settings -> Bluetooth” and ensure that it’s “enabled”. Then go to “menu -> settings -> I/O -> Bluetooth sensors” and make sure that they are enabled as well. Once these two settings are enabled, you should see the Ruuvitag appear on the I/O screen or on the first menu screen. You can navigate to the main menu screen by going back to “pages” and then pressing “menu” again or simply pressing the “back” button a few times to get to the main menu. On this main menu, you should see the Ruuvitag appear as something along the lines of “generic temperature sensor”. If you press on this device in the menu, you’ll open the Ruuvitag’s menu. You can check that you’re interacting with the right device by confirming that the “product” is a “Ruuvitag”. Next, you can give the Ruuvitag an appropriate name by navigating to the “device” option and then pressing on “name” which will launch a keyboard so you can name it something such as “Power System”. Now, if you haven’t already, you might want to switch the temperature units from Celsius to Fahrenheit (menu -> settings -> display & language -> units). If you don’t see this option, you’ll probably need to upgrade your firmware on the Cerbo GX to the latest version of Venus OS (menu -> settings -> firmware -> online updates). The same goes for if the Ruuvitags are not being “seen” by your Cerbo GX – updating the firmware will likely fix that as well. It’s worth mentioning that having temperature data on the Cerbo GX is pretty darn useful in other scenarios as well. For instance, if you have your system configured to send data to Victron’s free cloud service called VRM, you can get notifications pushed to you via email. Imagine if you’re traveling with a pet and you want to be notified if the interior temp goes above 85 degrees. Adding A Temperature Triggered Fan With a Cerbo GX Now that we have a temperature sensor with the Ruuvitag, we’ll dive into wiring up a fan (or multiple fans) to one of the relays on the Victron Energy Cerbo GX. You can use pretty much any 12-volt DC-powered fan and even combine multiple fans/loads running off the relay. In my van, I choose these fans and paired them up with these vents. The one limitation to be aware of is that the relay is only rated for 6 amps at up to 30 volts DC. However, most computer fans use very little power. There are two built-in relays on the Cerbo GX. Relay #1 has a lot more options as you can see in the screenshot below comparing the “function” choices for relay 1 and relay 2. For this reason, we recommend that you use relay 2 for this kind of “temperature” trigger so that relay 1 can remain available for other functions such as a generator start/stop, etc. Start by opening up the relay 2 options on the Cerbo GX (menu -> settings -> relay -> function (relay 2)). Then choose “temperature” from this menu as illustrated on the right side of the image above. Now, if you go back one menu with the “back” button (arrow in the very top left portion of the screen), you’ll see a new menu called “temperature control rules”. Below is a screenshot of this menu showing the various Ruuvitags in my van (temperature sensors) connected to the Cerbo GX. The next step is to choose which temperature sensor/Ruuvitag should be used as the relay triggering sensor. In my case, that’s the “Power Cabinet Temp”. Press on that sensor to open its menu which looks like the following. This is where you’ll configure the specific conditions where you want the fan(s) to turn on and off which are the “activation value” and the “deactivation value” respectively. Notice that there is a way to set two “conditions”. In our example, we’ll only use one. I have my fan set to come on at 90 degrees and to turn off at 84 degrees. If the “activation value” for “condition 1” has been met (temp inside the power cabinet is above 90 degrees), as was the case when this screenshot was taken, the “condition 1” will show as “active”. If not, it will show as “inactive”. Configure your activation and deactivation values to your liking – you can always return to this menu and change the settings! Wiring The Relay The last step is actually wiring up the relay. The Cerbo GX comes with a bunch of black terminal blocks that can plug into the bottom of the device for tank monitoring, relays, etc. So, you’ll need one of those. The illustration below outlines the wiring of the relay. The post discusses using relay 2 instead but the wiring illustration shows relay 1. The great thing about the terminal blocks is that they can be remove for ease of wiring and also be swapped from one relay port to the other. I think the illustration describes the wiring better than I can do in words, but basically, you’ll supply 12 volt DC positive from your system – likely from your 12 volt load center/fuse box, which will connect up to the relay’s “common” connection. The 12 volt DC negative wire can go directly to the fan/load since only the positive side of the circuit will be controlled by the relay. Then you’ll wire the NO (normally open) connection to the fan/load’s DC positive terminals. And that’s it! Now you can test the relay by adjusting the “activation” values to be close to the ambient temperatures and/or carefully heat up the Ruuvitag with a heat gun until the activation value temperature is met and you should see the relay come on (contacts close) to power your fan(s)/load!
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Accurate Tank Monitoring with a Cerbo GX and SeeLevel
Note: we sell a full kit with all the components you need to use the SeeLevel tank monitoring system with a Victron Energy Cerbo GX in our store. Save yourself time and headaches! Background I’ve been a big fan of SeeLevel tank monitoring products for a long time now. I used them in my first van conversion back in 2016 and a few projects since then. I’m also a really big fan of the Victron Energy Cerbo GX and most of our power system installations include one. So, you can imagine how excited I was when Victron Energy released version 2.90 of the VenusOS that runs the Cerbo GX including support for SeeLevel sensors! For a van nerd like me, this opened the door to using two of my favorite products together, and this post details what I’ve learned and how to do it. This paragraph may be one of the nerdiest things you’ll ever read… I own that! The best thing about the SeeLevel system is how easy it is to install. Traditional resistive sensors require a hole to be drilled into your tank and tend to give inaccurate results over time. The SeeLevel sensors simply stick onto the outside of your tank and, since they’re external, they don’t get fouled up by the liquids in the tank (particularly grey and black tanks). One important note is that SeeLevel sensors (senders) don’t work on metal tanks (must be plastic). How They Work The illustration below describes how the SeeLevel monitoring system works. There is also this video. What You’ll Need Note: we sell a complete kit with everything you need for this system in our store. As always, we appreciate your support. A SeeLevel 709-N2K-PM. It’s very important that you get the N2K (NMEA2000 version). There are some RV-C versions that can work with the Cerbo GX but, at the time we’re publishing this blog post, they prevent anything else from working on the VE.Can bus such as other Victron Energy components like a BMS, etc. This product is the actual “panel” that looks like the one shown in the illustration above. It’s designed to mount onto a wall in your rig for checking the levels of your tanks. So, you can locate that in a convenient location or choose to “hide it away” next to your Cerbo GX if you only want to reference the Cerbo GX screen for tank levels. There is a newer product from SeeLevel that’s called the Soul which does not come with the panel and supports up to 7x tanks. However, the Soul cannot be sold to DIY customers – according to the manufacturer (Garnet) that is an “OEM-only” product. Also, it speaks “RV-C” over the CAN network instead of NMEA2000 which is a problem (see above). One or more sensors/senders. You’ll want one sensor per tank in your system with a maximum of 3x (fresh water, grey water and black water). For instance, if you only have a fresh and grey tank, you’ll likely only need two sensors. The sensors come in the following options: The 710-ES2 sensor can monitor tanks between 5.5″ and 14″ tall The 710-AR sensor can monitor tanks between 3.5″ and 10.5″ tall If you have a very “tall” tank you can combine two sensors which is detailed in the manua; and sender/sensor guide. A Victron Energy Cerbo GX with an open/available VE.Can port CAN data cable. See details on how to make this cable below. Parts you’ll need for to make this cable are listed below. A standard UTP/network cable with RJ45 connectors. The CAN connection for the Cerbo GX is on the back of that panel so the location of the panel (and the distance to the Cerbo GX in your system) will determine how long of a cable you need. A 120 Ohm resistor, 1/4 W, 5%. 3M 37104, 4-pin connector. You should consider ordering a few extra of these since it’s kind of tricky to get all the wires into the connector without them pulling out. Creating a NMEA2000 “Network”Connecting the SeeLevel Panel to the Cerbo GX If you happen to already have a NMEA2000 network in your rig you’ll approach this very differently. But, for the sake of this post, we’ll assume you don’t. So, we’ll be making a cable that connects the 4-pin connector on the back of the SeeLevel panel to a VE.Can port on the Cerbo GX in the form of a NMEA2000 (N2K) “network”. The parts you’ll need for this are detailed just above. Note: we include a pre-made cable for this in our kit if you don’t want to mess with this yourself! To start, cut off one of the RJ45 connectors from the UTP/network cable you’ll be using. Then strip away about an inch of the outer insulation from that end. You should see 4 “pairs” of wires twisted together (8x total wires). The “pairs” are various colors and each “pair” has a “solid” and a “striped” wire. You’ll want to identify the brown and green pairs – you will keep those and cut away the others (orange and blue pairs). There may also be some plastic material inside with the wires than can be removed. At this point, you should have four remaining wires: brown solid, brown striped, green solid, and green striped. These will be wired up to the 3M 37104, 4-pin connector as shown in the illustration below. Untwist each of the 4x wires to separate them and then gently insert them into the correct location in the connector. Then, insert one end of the resistor into pin #2 and the other into pin #3. It can be tricky to get all these wires into the right “slots” and prevent them from pulling out. Take your time and only move onto the “crimping” step when you’re confident everything is aligned correctly. Now finish up the cable by crimping the connector. You can buy a special crimping tool to crimp this connector but we’ve found that a pair of pliers used to pinch the top of the connector down onto the bottom works fine. Attaching Sensors and Wiring Them to Panel The first thing you’ll want to do is “program” each sensor so that it can be assigned to monitor a specific tank (fresh, grey, black). Typically this is as simple as cutting away the correct “tab” at the top of the sensor. For instance, if the sensor will be used to monitor a grey water tank, you would cut away the tab labeled GRY. For fresh water tanks, you leave the sensor as-is and don’t cut any of the tabs. If your tank is so tall that you need two sensors to cover its height, these tabs are also part of how you’d “program” which sensor is the “top” and which was the “bottom”. Finally, if you have more than one tank of a particular type (i.e.: more than one fresh water tank for example), these tabs enable you to differentiate those as well. All of this is detailed in the tank senders manual but the illustration below is a simplified version that is likely to apply to most van builders. Next, you’ll attach the sensor(s) to your tank(s). This is super easy. Just peel away the backing on the sensor and attach it to the tank with its adhesive strip. Be sure that you’ve cleaned the tank surface where you’ll be sticking the sensor. Ideally, you want about 1/2″ of space below the sensor on the bottom of the tank and 1/2″ of space above the sensor on the top of the tank. Be sure there are no metal objects near the sensor (within 3-5 inches). I once had a SeeLevel sensor reporting funky values and traced it back to a metal strap that was securing the tank. Moving the sensor a few inches away solved the problem. If a sensor does not fit the full height of the tank, you can “justify” the sensor’s location to be either closer to the top or bottom, depending on the type of liquid. For fresh water tanks, it’s best to have them closer to the bottom since you’re typically most concerned about running out of fresh water, and for waste tanks (grey/black), you want them closer to the top since you don’t want to overfill those tanks. You can also pair two sensors together for particularly tall tanks as we mentioned above and as detailed in the manual. If a sensor is too tall, you can shorten it by cutting off a portion of its length. You simply cut the sensor at one of the spaces between the “pads”. Note that you must leave at least 3x pads at the top of the sensor. The top is where the wires are attached. This is all illustrated in the image below. If the tank is outside the rig, you can protect it from the weather by coating it with rubberized undercoating. SeeLevel specifically recommends 3M 03584 Professional Grade Rubberized Undercoating or Gravel Guard Rocker Guard Coating By Dominion Sure Seal. We’ve tested the 3M product and it works well. We tested another undercoating product from a local hardware store and it damaged the sensor! Once the sensor(s) have been placed the wiring is also quite simple. There is a white connector included with the system that plugs into the white connection on the back of the panel. It has the following 3x bare wires. The red wire should be connected to a circuit-protected 12 volt DC positive supply (likely to your 12 volt load center). The black wire should be connected to your 12 volt DC negative supply (also likely your 12 volt load center). This one will be “split” to each sensor. We recommend a Wago, lever lock connectors for this. The blue wire is also split to each sensor. Each sensor has a short, blue, and black wire that can be extended to the required length with additional wire. All of the black wires should be tied together and all the blue wires should be tied together which is illustrated below. Configuring the Sensors At this point, you’ll want to power up the SeeLevel panel and go into the settings to configure each tank. The SeeLevel panel we’re discussing in this post (and that we sell in our store) can monitor the “standard” 3x tank types found in vans/RVs (fresh, grey, and black). If you don’t have all three types, you can simply connect and configure the ones you need. In other words, if you only have a fresh and grey tank, it will ignore the “black” (“waste”) tank. Each tank needs at least one sensor/sender but, as mentioned above, you can use 2x sensors/senders on taller tanks in order to cover the full height of the tank(s). Using the Tank Menus This is confusing and you’ll probably have to read it a few times and then fumble around as well. I tried to write it as clearly as I can but it’s just not intuitive! To enter a specific tank’s menu, you press (and hold) the tank type and then simultaneously press the “batt” button. For instance, if you want to enter the black tank’s menu, press (and hold) the “black” button and then press (and hold) the “batt” button. Once you’re in the menu, the length of time you continue holding both buttons determines which option/setting you’ll be interacting with as follows. Releasing the two buttons selects that menu and, when you’re done interacting with the menu you press the “batt” button again to save and exit. Buttons held for 1 second: diagnostic information (diA shown on panel) Buttons held for 5 seconds: alarm options (ALr shown on panel) Buttons held for 10 seconds: connected sender/sensors (last two digits of r5 shown on panel) Buttons held for 15 seconds: tank capacity (last two digits of cA shown on panel) First, disable any tank types that you don’t have. For instance, if you don’t have a black tank, remove it by entering that tank’s “connected sender/sensors” menu (a ten-second press, see above). Once in the menu, press the “fresh” button to cycle through the options: SE0 = no tanks of this type (use this to disable this type of tank) SE1 = a single tank of this type (use this to reenable this type of tank if you’re adding it) SE2 = two tanks of this type Use the “batt” button to save and exit. Next, configure the capacity of each of your tanks. For each tank, enter that tank’s “tank capacity” menu (a 15-second press, see above). Once in the menu, you’ll see a number that represents the tank’s capacity in gallons. Use the “fresh” button to increase the number and the “grey” button to decrease. Use the “batt” button to save and exit. If you have already connected your SeeLevel panel to the Cerbo GX you’ll need to reboot it. Any changes to the SeeLevel configuration require a reboot of the Cerbo GX to be read correctly. Configuring the Cerbo GX Yay! It’s time to plug the SeeLevel panel into the Cerbo GX. The funky crimped side that you just made goes into the back of the SeeLevel and the RJ45 connector plugs into an available VE.Can port. Be sure to use a terminator in the unused VE.Can ports. They look like a connector without a cable (photo) and a few of them would have been included with your Cerbo GX. I recommend rebooting the Cerbo GX at this point. When it comes online, you should see a few things changed. The tank(s) should appear on the touch screen “pages” and in the menu as shown below. Note that you should only see the tanks that have one or more sensors configured. In other words, if you followed our example earlier and disabled the black tank monitoring by setting the number of connected black tank sensors to zero, you should not see it appear on the Cerbo. If you do, you can revisit those settings. You can now enter the settings for each of the tank sensors by pressing on its name from the Cerbo GX menu this should show you more information about the tank and its status. From there, if you press on “setup”, you see the tank’s capacity, fluid type, and volume unit as shown below. You can change the volume unit to gallons and then verify that what’s shown on the Cerbo GX matches the capacity you set when configuring the SeeLevel which is 30 gallons in our example image. Each “type” of tank that is enabled on the SeeLevel panel should come across on the Cerbo GX with a similar name: “fresh water”, “waste water” for grey tanks, and “black water (sewage)” for black tanks. As far as we can tell you cannot customize the name but you could use the “fluid type” menu on the Cerbo GX to change the label to something else. Finally, you may want to enable the “tanks overview” page/screen on the Cerbo GX that is shown on the right side of the image below. To do so, enter the menu on the Cerbo GX, navigate to “settings” and then “display & language”. This is shown on the left side of the image below. Other Resources SeeLevel II Tank Sender Manual Ross Lukeman's Video
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12-Volt Secondary Alternator Example Power System - Nations, Wakespeed & Victron
Jump To Example Wiring Diagram This post details how to install a powerful, super off-grid capable camper van power system that uses a Nations secondary alternator paired with a Wakespeed WS500 regulator, Victron Energy Smart lithium batteries, and a bunch of other Victron Energy equipment! This is part of a series of posts and we highly encourage you to check out the others! This post is an introduction to a 12-volt secondary alternator electrical system and why you might want to consider one for your van, RV, or other mobile application as well as a FREE example wiring diagram (see below) using Victron batteries and other gear that corresponds to our best price product bundle which makes it easy to get you everything you need at an awesome price! A video tour of this system installed into a Sprinter van that shows how it works. A technical deep dive video about the Wakespeed WS500 alternator regulator used in these systems. Other blog posts about a 24-volt secondary alternator power system and a 48-volt secondary alternator power system that also includes a FREE example wiring diagram and product bundle. Since this post was first written in September of 2021 we've helped many customers install these systems and we have them in our own personal vans, which are truly incredible! Update 2025: Our diagrams have been updated to use the latest Victron NG battery systems. This is a super long post where we've attempted to take all the knowledge we've gathered about a secondary alternator system for a van or RV and organize it into one place! Example Wiring Diagram We worked extensively with Victron Energy and Wakespeed to design a system that will work reliably and safely! However, electrical systems are complicated and we recommend that you either have your system installed by a professional or, if you do it yourself, have it inspected by a professional when it's completed. Please use the information provided at your own risk. Follow this link to gain access to our library of FREE Camper Van Electrical System Wiring Diagrams. Use the PDF files to print/zoom in. After following the link, open the Vanlife Outfitters 12V Secondary Alternator Wiring Diagram for our example wiring corresponding with this blog post. Why Use a Secondary Alternator? In the last year or so, we're seeing many more van builders including 400 to 600 amp hours (or more) of battery storage capacity in their rigs. Prior to that, a "large' system was maybe 300 amp hours. These higher capacity systems are absolutely fantastic for powering your loads for long periods of time while boondocking off grid. Massive battery banks even open up the possibility of using an energy efficient 12-volt air conditioner overnight (check out our comparison of these). However, there are three main problems with these large battery banks. First it's bloody expensive. But, if you want top-quality batteries with intelligent CAN bus-enabled BMS systems like our Victron Energy Smart Lithium battery example, you'll just have to bite that bullet. Secondly, it takes up a lot of space. Using fewer, higher density/higher capacity batteries, as we recommend in this post makes this much less problematic. Finally, with that much battery capacity – especially if you're using a lot of it regularly – it becomes nearly impossible to adequately recharge with solar or DC-DC chargers. As your battery bank grows in size, so does your need for charging. We think adding a powerful secondary alternator is the best solution to this problem. And here's the thing about a camper van…. you're going to drive it – that's sort of the point, right? So, if you can power everything in your van from the engine while driving (or the fuel tank you already have), you are going to have an incredibly capable off-grid rig. Imagine this: fast and reliable battery charging from a secondary alternator, water heating from your engine coolant lines with an Isotemp water heater, and perhaps a Webasoto gasoline or diesel heater sipping tiny bits of fuel from your van's tank. In fact, in many ways, this system makes having solar panels superfluous which can free up roof space on your van for vent fans, air conditioners and rooftop decks! But, What About Solar? Solar panel charging is a great "bonus" charging source when conditions are "just right" but it's not reliable like driving since conditions are often not optimal. Obviously, solar charging is only possible during the day and they have to be in the sun and, of course, you also have weather and seasons to contend with. We've seen some van builds that have their entire roof covered with solar panels so that they can generate enough power to run a residential-style "split" AC system which is a very complex installation by comparison to a rooftop unit and frankly, may not work correctly after bouncing down the road for thousands of miles. Think about this… they have to be parked in the hot sun during the day in order for this to work at all which is defeating to the goal because it will cause the air conditioner run more which means that there is less energy available to charge the batteries which will be needed to run the air conditioner through the entire night. In this example system we don't have any solar panels but they could certainly be added in the same manner as we have them on our other example camper van electrical system wiring diagrams. 1. The Nations 280 Amp Secondary Alternator Kit Our kit from Nations Alternator includes the powerful alternator itself which outputs an average of 200 amps and can surge up to 280 at high RPMs! When you compare that to a pair of 30 amp DC-DC chargers that are commonly used in a more "traditional" camper van electrical system, it's nearly 3.5 times more charging capability. In our testing, we see anywhere between 120-150 amps of charging current at idle and around 200 amps or higher when driving (depending on vehicle and engine RPMs). To put this into practical terms, without considering any solar charging, recharging a 600 amp hour battery bank at 30 amps while driving would take nearly an entire day (20 hours). If you used two Orion DC-DC chargers (which is fairly common), you'd still need to drive for about 10 hours to recharge. With this system, you can charge at an average of 200 amps which would take just over 3 hours of driving which is much more in line with real-world vanlife. You might spend two or three days at a campsite, off-grid, drawing down your battery, and then drive to your next destination. With this system, just a few hours of driving will restore your battery bank. The Nations alternator kit comes with everything you need for the installation including a vehicle-specific mounting bracket, hardware, belts, etc. The installation is not difficult for anyone who has some experience working on cars. It's also possible to hire your local mechanic to install the secondary alternator – something any qualified mechanic can help you with easily. One important feature of the Nations alternator that wasn't immediately obvious to us but was explained by our friends at Wakespeed is that it uses something called "avalanche diodes". Why is that important? Imagine your secondary alternator system is up and running, charging away as you drive and something goes wrong such as the fuse connecting the alternator output to your 12 volt DC bus blowing or someone accidentally disconnecting the battery(s) from the system using the disconnect switch. That situation is referred to as an "uncontrolled disconnect". When that happens the Wakespeed regulator (more on that below) can detect this and respond quickly with the alternator to dissipate the remaining electricity that now has no place to flow to (often referred to as a "load dump"). However, there is a brief period of time when voltage spikes significantly. If the alternator didn't use avalanche diodes, this voltage spike would be up to 130 volts (!) going into a 12 volt system, which is as bad as it sounds. However, with the avalanche diodes, the voltage is moderated to about 30 volts, and, get this, apparently, 12 volt systems are designed to handle voltage spikes up to 45 volts. Those diodes just saved your van! Nations Alternator Charging Capabilities Table 2. Wakespeed WS500 Regulator The Wakespeed WS500 regulator is the brains of the operation and interfaces with the alternator and batteries to charge the batteries with the correct voltage, current, and temperature parameters. You can think of the regulator as the device that turns the alternator into an intelligent battery charger rather than just producing current. And, like all battery chargers, it must be configured/programmed to charge the specific batteries you're using. The Wakespeed regulator is the most advanced regulator of its kind and is regarded by many in the marine/boat world as the very best and most reliable option. It constantly monitors 5 parameters of charging and is highly configurable. Want to learn more about the Wakespeed WS500? We have another post that is a technical deep dive on the Wakespeed including a 1.5 hour video with the founders! 3. High Quality, CAN Bus Enabled Lithium Batteries In a system this powerful, it's essential that the batteries are up for the job! They must be reliable, robust and one of the brands/types that is officially supported by Wakespeed to work correctly and safely. You can visit the "technical" support tab on the Wakespeed product page to see which battery brands are qualified for safe and effective use. Each of the qualified battery types has a corresponding configuration file available. In order to be considered for qualification, the manufacturer must provide batteries to Wakespeed for testing and engage in "engineer-to-engineer" level conversations with the Wakespeed team. These measures are to ensure that installers can have the highest level of confidence in the functionality and safety of their systems. We also highly recommend batteries that have CAN data connection to their BMS. CAN stands for "controller area network". It is a highly reliable standard that uses messages to allow many "devices" inside a system to communicate with each other. CAN is used extensively in the automotive industry and has various implementations in the mobile world including RV-C for RVs and NMEA 2000 in the marine world. If you have lithium batteries that have a CAN connection that the Wakespeed can read (or a "language" that it can "translate"), the Wakespeed will use the data available digitally on the CAN bus such as voltage, current, and temperature to very accurately control charging. It can also monitor other messages from the batteries such as disconnect warnings to prevent situations like load dumps. At Vanlife Outfitters, the CAN-enabled batteries we use in secondary alternator camper van electrical systems are Victron Energy Smart batteries (paired with a Lynx Smart BMS and Cerbo GX). Links to example wiring diagrams can be found at the top of this post! In addition to the compatibility, quality, and CAN bus, Victron batteries pack a lot of storage into a small space compared to most of the internal BMS batteries on the market which is, of course, a huge advantage in a camper van or RV! Installing Nations Alternator Installing the alternator onto your vehicle can be one of the most difficult parts of this system if you're not mechanically inclined and pretty familiar with working cars. That said, if you're up for the job, one of the things we love about the Nations alternator kits is how complete they are. The kits are unique to each vehicle and engine and come with everything you need to mount the additional alternator – from adapter brackets to belts. Typically you'll receive two boxes from Nations: one with the alternator itself and the second with the other parts. The kits include very good/detailed instructions so we won't dive too deep into the vehicle-specific installation process. In our experience, the Promaster kits are the most complicated and the Sprinter kits are the easiest and quickest. The Transit installation sits in the middle of this spectrum. One thing that does trip folks up during the installation is that there is only one "marked" terminal for wiring the charging current output to your system. It's labeled "B+" and is for the positive charging cable. The negative charging cable can connect to one of the large mounting bolt locations. Below is a photo of these wires connected to the Nations alternator on a Promaster van. We show 4/0 AWG wire used for these runs. If the length of this wire run is less than 15′ you can use the smaller, 2/0 AWG wire instead. In our experience, the Nations 280 amp alternator will output anywhere between 120 and 150 amps at idle and considerably more – 200 to 250 amps when driving. The range you'll see depends on your vehicle and the engine RPMs. Even the lowest output from the Nations alternator is very substantial compared to most other charging sources that are typically used in a camper van or RV such as solar or shore power. There are dozens of factors that determine how much power you'll get from a solar panel array (time of day, time of year, how dirty or clean they are, temperature, etc.), but a simple rule of thumb for averaging this range is to predict 5 amps of charging current to a 12 volt battery for every 100 watts of solar. So, even on a perfect sunny day, a roof smashed full of solar panels doesn't close to the alternator's output. Shore power is typically one of the most powerful and reliable charging sources. In this example system, the Victron MultiPlus 12/3000/120 inverter/charger can charge up to 120 amps. With these comparisons, you can see that charging at 200 amps or more is really amazing! Victron Smart Lithium Batteries The Victron Smart lithium batteries used in this example system are available in various capacities. We recommend either the 200 amp hour or 330 amp hour versions. Whichever size you pick, you should stick with the same capacity in your battery bank, and, importantly, you'll need at least 2x batteries (ideally 3x or more) in the system. All lithium batteries have a recommended maximum (continuous) charging current as well as a maximum (continuous) discharge current rating. Below is this information for the Victron Smart lithium batteries used in this example system. Looking at the 200 amp hour version of the battery (circled in red), you can see that the recommended charge current (highlighted in green) is 100 amps which is far less than the alternator is capable of charging. By adding two batteries, you aggregate this capability for a maximum recommended charge current of up to 200 amps. This is cutting it close since the alternator can charge beyond 200 amps – particularly if you have other charging happening at the same time – perhaps something like solar panels. While not ideal, it would work since the Wakespeed is aware of the charging current that's being generated AND the capabilities/limitations of the batteries so it will respect the limitations and state of the battery. More on this is below in the Wakespeed configuration section of the post. If you use the 330 amp hour version of the Victron Smart lithium batteries, the recommended maximum charging current goes up to 150 amps per battery giving you plenty of extra headroom. On the discharge (load) side of the equation, in most systems, the inverter/charger is the biggest draw since it can power energy-hungry things like microwaves, induction cooktops, 120VAC air conditioners, etc. In the example system, we're using the popular Victron Energy MultiPlus 12/3000/120 inverter/charger. Taking another look at the specs for the 200 amp hour version of the Victron Smart lithium batteries, you can see the recommended discharge is 200 amps (highlighted in yellow). Meanwhile, the MultiPlus inverter/charger can run loads greater than 3000 watts for long periods of time which is 230-250 amps depending on the load and the battery voltage at the time. So, once again, having 2x or more batteries in parallel gives you the performance you need. The Brains: A Lynx Smart BMS with the Cerbo GX The Victron Smart lithium batteries require an external Battery Management System (BMS). Externalizing the BMS has quite a few advantages that we detail in this other blog post. One major advantage of this particular system is that it enables the Wakespeed regulator to communicate with the BMS (and therefore the batteries) digitally via a CAN bus which makes the system more robust and reliable. It also opens up the possibility for some pretty cool monitoring. More on that later! The external BMS also means that the batteries themselves pack more power into a smaller space compared to batteries with an internal BMS as illustrated in the image below. The BMS we're using in this system is the Victron Energy Lynx Smart BMS. By the way, any Victron Energy component that has the word "Smart" in its name means that it can be configured, monitored, and controlled via Bluetooth with their free VictronConnect app. In addition, this system uses a Victron Energy Cerbo GX. You can think of the Cerbo GX as a tiny computer with an operating system that is specifically designed for mobile power systems like your van or RV (VenusOS). You connect up all your electrical system components to the Cerbo GX using its wide range of "inputs" and the Cerbo GX allows you to monitor and control them through a simple touchscreen interface. Typically this is facilitated through either the 5″ Touch 50 display or the 7″ Touch 70 display but you can also be done via Bluetooth or even remotely through the Victron Remote Monitoring service called VRM. You can also connect things like water tank sensors, temperature sensors, and more. If you take a close look at our example wiring diagram, you'll see that the 3x batteries have a short cable coming out of them with circular (M8) connectors. You connect each battery together (daisy chained) with these cables and then that chain of batteries is connected to the Lynx Smart BMS with a longer set of these same M8 cables. Then, the Lynx Smart BMS is connected to the Cerbo GX using VE.Can. CAN stands for "controller area network". It is a highly reliable standard that uses messages to allow many "devices" inside a system to communicate with each other. CAN is used extensively in the automotive industry and has various implementations in the mobile world including RV-C for RVs and NMEA 2000 in the marine world. Victron's version is called VE.Can and uses RJ45 (ethernet style) connectors. With all this wired up, the batteries can communicate with the Lynx Smart BMS which can, in turn, communicate with the rest of the power system through the Cerbo GX. OK, back to the BMS. Its job is to listen to the batteries to make sure that they are never damaged. Specifically that they don't get overcharged (over voltage), too discharged (under voltage), too hot, or too cold. The Lynx Smart BMS is part of the Lynx system from Victron. Many people use the Lynx Distributor in their power systems because it's a very clever combination of two high-capacity bus bars (DC positive and DC negative) with circuit protection with (Mega fuses) on each of the DC positive terminals that are packaged up in a compact case with a cover. The Lynx Smart BMS bolts right onto one or more Lynx devices. In our example system, we use 1x Lynx Power In and 1x Lynx Distributor as illustrated below. The Lynx Power In is on the left side and is used to connect each of the batteries to put them in parallel. The wires from the batteries to this Lynx Power In should be the same lengths and the positive cable run is protected by a 250 amp terminal/MRBF fuse. Note that you can use a Lynx Distributor for this left-side/battery connection point but the fusing inside the Lynx Distributor would be slightly redundant. In the middle is our Lynx Smart BMS. Inside the Lynx BMS are two important things. One is a current shunt on the DC negative side. This allows the BMS to also serve as a "battery monitor" which is similar in function to the popular BMV-712. The second is an integrated, 500 amp "contactor" which is the equivalent of those large, typically red, main disconnect switches you see in so many power systems. Finally on the right side is the Lynx Distributor that is wired up to all the loads and charging sources. Now that you can visualize how all these components fit together, let's discuss how they work together. Think of the batteries as the boss. They are one of the most expensive parts of your power system, so it's important to protect them from distress (over voltage, under voltage, too hot, too cold). The Cerbo GX is the brain. It's connected to the BMS and most everything else in the system (inverter/charger, solar charge controller, etc.). And, of course, the BMS is the manager (remember, it stands for Battery Management System). The BMS is always listening to the batteries and is responsible for responding if they are distressed. Meanwhile, the Cerbo GX can communicate errors or issues to you and other system components which should respond to the boss. Disconnecting Loads & Chargers to Protect the Batteries Let's consider how the Lynx Smart BMS can manage some key functions: Disconnect loads from discharging when necessary which is typically when they are overly discharged (low voltage) or too hot or too cold. Stop any charging when necessary – typically when the batteries are overcharged (high voltage) or too hot or too cold. Discharge ControlIn this system, there are what we refer to as "smart" loads that are connected directly to the Cerbo GX which can relay messages from the BMS on behalf of the batteries and control those connected loads digitally. For example, the Victron MultiPlus inverter/charger can stop powering loads when told to by the system. Very smart. Then there are the "dumb loads". We refer to them as "dumb" because they can't communicate directly with the Cerbo GX the way the "smart" loads can. In this example system, that would be everything that is wired up to the AD/DC load center on the DC side – things like lights, refrigerator, vent fans, and 12 volt outlets. Another example might be a 12 volt air conditioner that is wired up to a terminal on the "loads and chargers" Lynx Distributor (right side). But, take a look at the illustration of the Lynx system above. These "dumb" loads are electrically "downstream" from the main disconnect switch (contactor) that is built into the Lynx Smart BMS. This opens up two ways to handle load disconnects of "dumb" loads. The simplest approach is to let the BMS turn off (open) its integrated contactor/switch which will electrically disconnect (turn off) everything connected on that right side Lynx Distributor (including charging sources). This is what we show in our example diagram. Obviously, you don't want this to happen while you're out there camping in your van so you'll want to pay attention to any warnings on your touch screen and monitor your battery state of charge. The other way is to make use of the ATD (allow to discharge) relay available on the Lynx Smart BMS to create a sort of "staggered" shutdown where specific, chosen loads, such as your 12 volt load center are disconnected before the entire system shuts down. This might be particularly important in a marine environment where you would want to shut down something like your refrigerator before everything on the boat, including your navigation equipment! The Lynx Smart BMS has a bunch of terminals on the bottom that Victron calls the "multi connector" (see photo below). Our example wiring diagram illustrates how we will connect to many of these. If you wanted to have the type of staggered shutdown we describe above, this is where you could also wire up a Smart BatteryProtect device to the so-called ATD (allow to discharge) relay that can be configured to disconnect the loads that is supplies power to (such as a 12 volt load center/fuse box or a 12 volt air conditioner, etc.) BEFORE the entire system shuts down as a result of the main contactor/switch in the Lynx Smart BMS opening/shutting off. Charging ControlOK, now let's turn our attention to disabling charging side of the equation in situations when the batteries tell the BMS they don't want to be charged. Here again, the so-called "smart" chargers that are communicating directly with the Cerbo GX/BMS can receive and respond to the triggers digitally. So, just like the discharge example above, the MultiPlus inverter/charger can be controlled in this way to stop charging. The same is true for a Victron Smart MPPT solar charge controller that has a VE.Direct connection to the Cerbo GX – which is the majority of them. The last charging source in our example system is the dedicated, secondary alternator that is being regulated by the Wakespeed WS500. Similar to the ATD (allow to discharge) relay on the Lynx Smart BMS that's described above, the Lynx Smart BMS also has an ATC relay (allow to charge) relay. In this system, we will be wiring up the "feature in" (white wire) from the Wakespeed "van harness" such that it receives this ATC (charge disconnect) signal to stop charging when the batteries trigger this state. This is illustrated in the example wiring diagram and detailed more in the Wakespeed wiring harness and configuration section of this post. This ATC circuit is actually a backup to the main communication over the CAN network. Wakespeed WS500 Regulator Now that the batteries and BMS are all sorted out, let's talk about the Wakespeed WS500 regulator and how it's used in our example system. We'll keep this fairly basic, but if you want to take a much deeper dive, you can check out our video with the Wakespeed creators. The Wakespeed regulator turns a fairly basic, but very powerful Nations alternator, into an intelligent, reliable, and smart charging source for your batteries. As we mentioned before, you've spent a ton of money on the batteries, so it's essential that the charging equipment is compatible and will respect the charging profile of the batteries and that's exactly what the Wakespeed does! Later in this post, we'll discuss how to configure the Wakespeed to charge the Victron Smart lithium batteries used in this system. CAN Wiring and Wakespeed "Van Harness" Check out our other blog post/video that details every connection on the Wakespeed WS500 van harness. The Wakespeed regulator should be located near the rest of your primary electrical system components such as the batteries, inverter/charger, etc. In a camper van, this is quite often near a rear wheel well in the back of the van. In our example system, we're using the "white box" version of the Wakespeed regulator that incorporates two RJ45 CAN connections on the bottom of the unit which are the same "ethernet style" jack that you'll find on the VE.Can port of Victron Cerbo GX. Note: in early 2024, the formerly "white box" version of the Wakespeed regulator starting shipping with a black, plastic case. However, the Victron equipment uses a different wiring configuration than the Wakespeed so you'll need a special Victron to Wakespeed crossover cable that has a blue connection on one end which plugs into a VE.Can port on the Cerbo GX and a black connection on the other end which plugs into one of the Wakespeed's CAN ports. This crossover cable comes with a black resisting terminator that should plug into the other CAN port on the Wakespeed and your Cerbo GX will come with a few blue resisting terminators that you'll put into all the empty VE.Can ports on your Victron equipment (typically one on the Lynx Smart BMS and one on the Cerbo GX). In the example system, we illustrate how to wire up the "van harness" for the Wakespeed regulator. It has a large, main connector that plugs into the big multi-pin connector on the bottom of the Wakespeed. From there the harness has three legs which are detailed in the example wiring diagram and outlined below. If you want to see photos of the real thing on our messy work table, you can check this photo album. Alternator LegThis leg is the longest (about 27′) and is designed to run from the back of your van where the Wakespeed is probably installed, all the way up to the engine area where the Nations alternator will bolted onto the engine. There are two connectors on this leg: one is a black connector with green heat shrink that plugs into the temperature sensor connector coming off the Nations alternator. The other is a grey connector with a blue and a yellow wire. This connector (circled in red in the photo below) should be cut off. Then, the yellow wire that was part of that connector is not used (can be tapped off) and the blue wire that was part of that connector should be butt spliced onto the green wire coming off the Nations alternator. Power System LegThis leg is the shortest since the connections on this leg are typically installed near the Wakespeed which is typically located with the rest of your primary power system components. It has a connector with blue heat shrink that can be connected to an optional battery temperature sensor which we don't use in our example system. Then there are four unterminated/bare wires: The red wire should be connected to the same terminal on the DC positive bus bar of the Lynx Distributor that the Nations alternator's DC positive charging output is connected to with an inline, 5 amp fuse. The black wire should be wired up to the DC negative bus bar of the Lynx Distributor. The white wire is called the "feature in" wire and it's the one we use to send the ATC (allow to charge) signal that was discussed above into the Wakespeed to disable charging if the batteries trigger the BMS to do so. Specifically, it's wired into terminal #9 on the multi connector of the Lynx BMS and there is a short "jumper" wire between ATC terminal #4 to the relay "common" terminal #8. This is confusing! Please see the example wiring diagram for an illustration and zoom into the detail of this multi connector's wiring. If you're using a current shunt (strongly recommended), the purple wire is connected to the small terminal on "alternator" side of the shunt and the grey wire should be connected to the small terminal on the "battery" side of the shunt for current monitoring. Ignition LegFinally, there is a long, brown wire that is designed to be connected to an ignition-controlled circuit. This brown wire turns the Wakespeed on/off (and thus the alternator charging system). If the brown wire "sees" 8.5 volts or higher, it will turn on and enable charging. Typically you would wire this brown wire up to a circuit in your van or RV that is only on (providing voltage) when the ignition switch is enabled or the engine is running. We further recommend that you wire in a toggle switch on the brown wire circuit so that you can turn the Wakespeed/alternator charging off when desired – even when the vehicle/ignition is on. Why This Is Awesome Example #1Running a Mabru 12-volt Rooftop Air Conditioner Overnight with 600 Amp Hours of Battery Capacity Let's run a scenario where you run a Mabru 12,000 BTU air conditioner in your camper van overnight for 8 hours. Let's assume it's cycling on and off about half of the time such that the compressor is only operating for 4 hours during that 8-hour block of time. I'm choosing the Mabru unit in this example because of its extreme energy efficiency. If you take a look at our comparison spreadsheet, you'll see that the Mabru uses about the same amount of power as the Dometic 2000 RTX while producing nearly twice the cooling capacity! The reason is that Alain Mabru has leveraged his decades of marine cooling experience to engineer an innovative "inverter" system for the compressor. This design provides substantial improvements in energy efficiency, quieter operation and longer longevity than traditional compressors. Scenario #1, it's freaking hot. So, you're operating the unit on "high" with medium fan speed. That's going to draw about 55 amps. Running for those four hours (50% duty cycle overnight) would consume around 220 amp hours from your battery bank. This means that, with no other loads,you have something like 380 remaining amp hours of capacity for other loads throughout your day and you could fully restore the energy consumed by the air conditioner by driving (or idling) for just over one hour! Scenario #2, it's hot but not freaking hot. In this case, you're operating the unit in the "eco" mode drawing around 25 amps for the same 4 hours (50% duty cycle overnight). In this scenario, you would consume only around 100 amp hours from your battery bank which means that you have something like 500 remaining amp hours of capacity for other loads throughout your day and you could fully restore the energy consumed by the air conditioner by driving (or idling) for only around a half hour! Configuration With everything wired up, let's dive into configuring the system! Given the nature of this post, we're only going to focus on the configuration steps for enabling the secondary alternator and Wakespeed regulator. One awesome feature of this system provided with the Lynx Smart BMS is that the charge profile for the other Victron Energy chargers in our example system (MultiPlus inverter/charger and solar charge controller) is managed intelligently by the Cerbo GX using DVCC. This is possible because all of these devices are "talking" to each other digitally through the Cerbo GX. If you want to learn more about this DVCC magic you can read this section of the Cerbo GX manual. But, If your system has other chargers/devices that don't have a data connection on them (no VE.Bus, VE.Direct, VE.Can, etc.), such as an Orion DC-DC charger, and therefore cannot be managed by DVCC, you'll have to configure that device the "old fashioned" way with VictronConnect which is beyond the scope of this post. We also won't discuss all the setup possibilities of the Cerbo GX – you can check out this other post about that. Instead, we'll only focus on what's necessary to make it work with the Wakespeed regulator. However, we'll be dedicating another post to the Cerbo GX including connecting it to VRM so "stay tuned" for that, or consider signing up for our email newsletter which is available at the bottom of all of our pages. Victron Lynx Smart BMS Configuration with VictronConnectRemember that any Victron product with the word Smart in the name means that you can configure, monitor, and control it via Bluetooth using the VictronConnect app. So, if you haven't done so already, you'll want to install VictronConnect. Links to download the app are available for iOS, Android, Windows, or MacOS on the VictronConnect page. Most folks find the app simple to use but you can read through the manual if you need it. To use it, you'll need Bluetooth enabled on your mobile device or computer so that it can communicate with the various Victron products. Once you open the app, you'll see a list of all the Victron products that are within Bluetooth range -all with their factory default names. You can easily rename each device to make it unique to your install if you'd like. To configure (or monitor/control) a device simply click on its name from the list in VictronConnect. The first time you connect you'll be asked to pair with that device. For "older" models, the default pairing PIN is 000000. On "newer" versions the default PIN code will be printed on the sticker on the device. We recommend you change the PIN on all your devices so that other users of VictronConnect don't mess with your system! Keep in mind that if you find yourself in a place with other camper vans/RVs that have Victron components you might see a bunch of other devices listed in VictronConnect – basically anything that's within Bluetooth range. By the way, if you don't have any of this equipment yet but are curious how it all works, you can actually use VictronConnect with "virtual" (demo) devices. In other words, you can go through the settings and screens available in VictronConnect for any Victron Smart product by using the demo library available in VictronConnect. This is a great feature to use when planning a system. Let's start with the Lynx Smart BMS. Connect to this device in VictronConnect. The first screen you'll see is the "status" tab that displays the same kind of information as other battery monitors from Victron including the calculated state of charge (SOC) as a percentage and if you scroll down, a bunch of other information about the battery including voltage, current, etc. Below is a screenshot of this screen. Take note of the area circled in red: "allow to charge" and "allow to discharge". Earlier we discussed these modes that get triggered by the batteries when they are in distress. This is where you can see if these states are triggered. There are several other screens that we won't detail here but you can read more about them in the manual. Next, click on the "gear icon" in the very top right of the screen to enter the settings. You can use the following screenshot as a guide to these settings however, be sure to set the "Battery bank capacity" and "Number of batteries in parallel" to reflect what is in your particular system. These settings are outlined in red below. In the screenshot, they are set to 600Ah and 2x batteries to match the example system. The rest of the settings we show are fairly universal and typically a good starting point for your system. Also note the "Relay mode" setting that we've outlined in green in the screenshot above. This is how the "white wire" (feature in wire) that we wired from from the Wakespeed harness into terminal #9 on the multi connector of the Lynx SmartBMS is interpreted by the BMS. It enables the ATC (allow to charge) relay to disable charging from the Wakespeed/Nations if the battery triggers that state. Note: if you've ever configured another Victron Energy battery monitor such as the BMV-712 or SmartShunt you may notice that the settings presented here are different and, in some ways, more simple than you'd see on the other products. That's because, in this example system, you can literally only use one single type of battery – a Victron Smart lithium battery. The batteries may be different capacities (200 vs. 300Ah, etc.) but they are the same baseline so many of the settings about the battery that you have to change/set in other systems are already known/assumed in this case. Wakespeed WS500 ConfigurationIf you buy your Wakespeed regulator from us as part of a best price secondary alternator product bundle, it will ship pre-configured based on the information we collect when you add the stuff to your cart. However, configuring a Wakespeed WS500 regulator is pretty simple when using the Wakespeed Android app. Note, at the time we're writing this post, there is a version of the Wakespeed app available for Apple, iOS devices but it can't connect to the Wakespeed via USB so it can only create and manage configurations – not communicate or send them to the Wakespeed. In addition to the Android app and device, you'll a USB "on the go" (OTG) cable with one end matching the USB connection on your phone (most Android phones now use USB-C) and the other end having a standard, USB-A female plug such as this one. You'll also need a short USB-A to USB-B cable. The USB-A end of this cable will pair up with the OTG cable and the other will plug into the USB port on the Wakespeed regulator that is accessed when you remove the lid. Once you have this all connected you can take a look at the following video that does a great job at introducing how to use the Wakespeed app for configuration. Now that you know the basics of how to use Wakespeed app, below is a video of us configuring the Wakespeed regulator for this example system. Note that we're showing 2x batteries instead of three. This is another place where your particular settings need to be adjusted to match your system's battery count and storage capacity. In the video, we show the settings you would enable or disable depending on if you have an analog current shunt. More on that is below. Optional Analog Shunt for Monitoring Nations/Wakespeed Current On Cerbo GXIn our example wiring diagram we show an optional Victron Energy analog shunt wired into the Nations alternator's DC positive charging output wire. We recommend you include this in your system but it is not required. You'll probably want to locate this shunt close to the rest of your power system components – near the "loads and chargers" Lynx Distributor. The purpose of this shunt is to measure the current flowing from the Nations alternator distinct from the "main" current shunt in this system which is one integrated into the negative bus of the Lynx Smart BMS. In other words, if you add this shunt, you'll be able to see the current (in amps) and power (in watts) being generated by the Nations alternator when you view the Wakespeed in your system on the Cerbo GX as illustrated below. The left side screenshot is before a shunt was installed in our demo system (outlined in red) and the right side is after (outlined in green). This is pretty cool and allows you to see how much current is coming from the alternator alone without the other charging sources or loads being considered – much like you would be able to see on a solar charge controller. For instance, if your Nations alternator is charging at 150 amps and your solar array is charging at 20 amps and, at the same time, your 12 volt rooftop AC is running and using 55 amps, if you were to look at your primary battery monitor (the Lynx Smart BMS) you'd see an aggregate current readout of something like 155 amps (170 being supplied and 55 being used). Meanwhile, you could take a look at the solar charge controller specifically and see that it was charging at 20 amps alone and look at your Nations/Wakespeed and see it's charging at 150 amps alone. Note that the Wakespeed can be "powered" in two ways. Normally it would be powered by your van's power system via the "brown wire" discussed above (ignition trigger wire, on/off wire). Alternatively, when configuring the Wakespeed via USB, the USB cable will supply enough power to turn the unit on. This is very handy for configuring a Wakespeed regulator prior to installation into a system. About "Reading" the Configuration of a Wakespeed Regulator One thing you may notice if you experiment with the Wakespeed Android app enough is that if you edit the settings in the configuration screens and send that configuration to the Wakespeed using the "configure device" and then use the "copy" feature that reads the config file from that device back into the configuration screens of the app, most of the settings you'll see in the configuration window will NOT match what you think you had set up. The same thing can happen if you connect up to any pre-configured Wakespeed regulator using the Android app expecting to see the configuration options "match" the options in the user interface. Why is this? When you're configuring a Wakespeed using the app interface, what is happening "behind the scenes" is that your selections are getting "translated" into a "lower level" configuration file that looks something like the screenshot. In other words, the app is allowing you to create a config file in a user-friendly way but, at a deeper level, many of the choices you're making are getting converted into the values and formatting the Wakespeed actually needs to be programmed. When you "copy" a current configuration of a Wakespeed, you're retrieving this 'lower level" file that, when opened in the app, doesn't line up with the selections available in the user interface. Thus, when you do a "copy" you're actually creating a brand new configuration file. Firmware If you're experiencing problems with your system be sure that the firmware is up to date on all the devices. On the Wakespeed you do this from the Wakespeed app. Tap on the "home icon" at the top left and then select "device" and finally "firmware update". You need version 2.5.0 or higher for the system to work correctly with the Cerbo GX. On the Cerbo GX you'll need to have version 2.90 or higher of the Venus OS. You can check this by opening the menu, navigating to "settings" then "firmware" then "online updates" and then press on the "check and update" button. On the Lynx Smart BMS you'll open that device up in VictronConnect then press on the "three dot menu" in the top right part of the interface and choose "product info". Find the "firmware" link and press update. Flashing Orange Light When the Wakespeed is up and running and configured correctly in this system you should see its LED light flashing a "reddish orange" color. This has alarmed some of our customers who think that the flashing LED indicated some kind of problem but, in fact, it means that the Wakespeed is being controlled by an external BMS which is exactly what you want in this example system. Common Errors/Conditions with the Wakespeed WS500 Regulator Error 51If you've wired your Victron Lynx Smart BMS remote terminals to a toggle switch in order to be able to use the built-in "contactor" to turn the system on/off as you might with a typical main battery switch (those big red switches) you will get an error 51 thrown by the Wakespeed regulator when you use the toggle switch to turn off the system. The reason is actually good news. When you trigger the remote off function, the Lynx Smart BMS is able to send a message over the CAN bus to the Wakespeed regulator that puts it into this fault code and disables charging before it actually turns off the system (opens its internal contactor). This allows the Wakespeed to stop the Nations alternator from charging before the batteries are disconnected preventing a "load dump" which can be harmful to the alternator and your system. Think of it as a helpful "head up" prior to the disconnect. If you see an error 51 in this context, this would be the most likely reason. The only way we've found to reset this error is to make sure the Wakespeed is switched off (ignition/brown wire) and then the RJ45 CAN connection out of the Wakespeed regulator for a few seconds and then plug it back in. Error 91This error indicates that the Wakespeed has lost its connection with the Lynx Smart BMS and it will go into a "get home mode". As soon as the communication is restored it will revert to the charging goals set by the BMS. Error 92The ATC (allow to charge) state has been triggered by the batteries and the Lynx Smart BMS has communicated this to the Wakespeed and, as a result, the Wakespeed has been turned off to disable charging. Error 44The WS500 is capable of providing a broad range of error and advisory codes, which are displayed by the LED that's exposed via the jewel on the lid of the regulator. Error codes are preceded by two red "bursts" of flashes, followed by a two-digit display of flashes. In the case of an error code 44 (indicated by four flashes, a space, and four more flashes), the regulator has monitored an excessive voltage difference of greater than 2.5VDC between the regulator's positive voltage sense (red w/yellow tracer) wire and positive power (solid red) wires. This may indicate an excessive voltage drop between the two wires, or the existence of a damaged fuse in one or the other wire. A full list of error/advisory codes is available in the WS500 Communications and Programming Guide, available on our website. Powering Up and Testing Power up the DC system by turning "on" the switch wired into the Lynx Smart BMS "remote" terminals thereby closing the contactor inside the BMS. Confirm that the small loads like the Cerbo GX are powering up. Turn on the MultiPlus inverter/charger with the power switch on the unit itself. When the Cerbo GX running, try controlling the MultiPlus from the Touch 50/Touch 70 screen (switching modes from off/charger only/on, etc.). If you have issues with this, make sure the VE.Bus connection between the MultiPlus and the Cerbo GX is correct (RJ45 UTP network cable) and you're using a manufactured (not hand-crimped) cable. Confirm that you are getting 120 volt AC to your load center (from the AC output 1 terminals on the MultiPlus). Confirm that you are getting 12 volt DC to your load center. Configure the various Victron Smart devices using VictronConnect via Bluetooth. Configure your Cerbo GX and connect to the free Victron Energy VRM cloud service. Test the secondary alternator by starting the vehicle and then turning on any switch that may be wired into the "brown, ignition trigger wire" of the Wakespeed WS500 harness. Once the vehicle is running and the Wakespeed is powered up, you should see the LED light on the Wakespeed flash an orange/amber color indicating that it's being controlled by a BMS. In this case, that's the Victron Lynx Smart BMS. Confirm that you're getting a charge current from the alternator by looking at the battery monitor (shunt inside the Lynx Smart BMS) information on the Touch 50/Touch 70 connected to your Cerbo GX. Note, if the batteries are close to full this will be a small amount of current necessary for an absorption charge. You can discharge the batteries using a heavy load such as a heat gun or similar high-wattage appliance in order to see the alternator's output during a bulk charge. Test your shore power input to make sure that the MultiPlus syncs to the incoming 120 volt AC power and that the internal transfer switch transfers the loads to the shore/utility power. You'll hear an audible click. Additional Resources Wakespeed WS500 Technical Deep Dive Video Wakespeed WS500 Regulator Manual Wakespeed Video Resources
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Sizing Your Electrical System & Load Calculations
One question we are asked all the time is “how many batteries do I need for my van’s power system”? Or, how many solar panels do I need to run my AC?” This is a very simple question with a stupidly complex answer. I mean, look at how long this blog post is. Ugh. First, solar panels are a charging source – typically one of many. Don’t conflate a “solar system” with what you actually need, which is a complete power system. We’ll dive into that more later but, for now, let’s start by rephrasing the question to “how much battery capacity do I need to be off-grid in my van”. Water Analogy One simple way to think about this is to use a slightly more familiar analogy: how much water do you need in your van? Which, of course, depends on how much water you’ll be using. Do you shower every day? Do you never shower (don’t be like that)? Are we talking about a long luxurious shower or a quick rinse? How much water do you drink? How often do you do dishes? You get the idea. Everyone’s answer is going to be different. So, let’s start by thinking about batteries as tanks of water – each containing a specific amount of water measured in gallons since many of our readers/customers are ‘Mericans. In batteries, we’re measuring stored energy – just like the stored water in a tank but, instead of gallons, the metric is amp hours or watt-hours. In water systems, the amount of water you use depends on the flow of a tap/valve. If you turn the faucet on full blast your tank will empty much quicker than if you have it running at a trickle. In electricity, your faucets are what we call “loads”. Some loads, such as LED lights or charging a phone, are small (a trickle of water). Other loads are large (a firehose of water) such as an air conditioner or an induction cooktop. In power systems, the flow rate is called current (amps) and the pressure is called voltage (volts). So, just as you have a finite and measurable amount of gallons in your water tanks, your batteries also have a finite and measurable amount of amp hours in them. How to Monitor Consumption Every electrical system should have a capable battery monitoring system such as the Victron Energy BMV-712 or SmartShunt. It gets wired into your electrical system like a water meter is installed onto your house. As you use power it will track your usage against how many amp hours you had to start with when the battery bank (tank) was full. With this information, it can tell you, with reasonable accuracy, how much power you have left in your batteries (and other stuff). Load CalculationSucks, But Worth It So, how many amp hours do you need in your tank? It’s going to take some math kids! You need to do what’s called a load calculation. Fair warning, this is going to take an hour or two and isn’t particularly fun (it sucks) but it’s worth the effort. To get you started, we have a free example load calculation Google Sheet. If you click on the link it will open up and prompt you to make a copy. Note, that you’ll need a Google/Gmail account to use this Google Sheet. Once you have your copy you can experiment with it and edit the values as you see fit. There are three example sheets that you can use as launching pads for your system: The first sheet/tab (named “Ex. 1: 600 Watts Solar, Moderate Driving, 12v AC”) is a larger system – it has pretty typical loads but also adds a Mabru 12 volt air conditioner that is run for a few hours every day. It has three, standard charging methods (much more on that later). In a system like this, you’d probably want to use external BMS batteries to take advantage of the significant space savings they provide and this best price product bundle would be a good starting point. The second sheet/tab (named “Ex. 2: 400 Watts Solar, Moderate Driving, No AC “) is a more modest system that is similar in loads but has a smaller solar array and omits the air conditioner making the total consumption much lower. It’s a good candidate for 2-3x internal BMS batteries and this best price product bundle. The third sheet/tab (named “Ex. 3: No Solar, Driving w/ 2nd Alternator, 12v AC”) is the most powerful system that uses a dedicated secondary alternator for rapid charging and doesn’t have/need any solar panels at all. It has all the same loads but assumes the AC unit will run all night. In this van, you can imagine the owner having a nice roof deck or other ways of using that roof space. We have a best price product bundle for secondary alternator power systems as well! But, hang on. Resist the temptation to dive into those spreadsheets right now and start tweaking the numbers. We suggest you read on a bit further to know what they mean first. The first step is to identify all your loads – everything that is going to be powered by your electrical system: lights, Maxxfan, refrigerator, microwave, blender, coffee maker, chargers, Christmas lights, flame throwers, all of it. As you do this, keep two lists: one for things that run off 12 volt DC – directly off the battery. And another for things that require household power – 120 volt AC – things that have a plug that you’re used to using in your house – a normal outlet. To power 120 volt AC loads, you need something called an inverter. It is wired to your batteries and converts (inverts) the 12 volt DC (direct current) to 120 volt AC (alternating current). OK, take a quick peep at your copy of the load center worksheet. In all of the examples, you can see that there are four sections/tables. Go ahead and list out your DC loads in the top table and the AC loads in the next table below – into column A. Don’t worry about the numbers yet but feel free to add “rows” if needed to accommodate your list of loads. Now that they’re all listed you have to find out the power consumption of each. Going back to our water analogy – is this thing a drip or a firehouse? We want to put those numbers into this “amp draw” column (column B). DC Loads You can start with the DC stuff since it’s typically easier because often the sticker or info you find will already be listed in amps. That’s handy and will save you some math. AC Loads Now let’s do some of the AC loads. Quite often the power consumption of AC devices are listed in watts. To convert that into amps, we’ll use the following formula. I know, math. I agree. It’s simple tho. The formula is:Amps = Watts / Volts In this case the volts in your battery voltage. We talk about 12 volt batteries but that’s honestly a pretty deeply discharged battery. The “nominal” voltage on a battery you’re likely to use is 12.8. So, here’s an example. An induction cooktop says it uses 1800 watts. However, that’s the maximum draw on super-duper-high. Typical consumption is closer to 1200 watts. Even so, it’s typically best to plan for the “worst case scenario” in these load calculations. So, our math to convert this into amps is 1800 divided by 12.8 which is 140 amps. Yipes! Compare that to our LED puck lights at 1.5 amps. Those are the drips and the cooktop is a true firehose. So, go ahead and list out all your AC load values into column B of that middle table. Time Now we can get into the last variable – time. Going back to our water analogy, we know that long showers consume more water than short ones – even when the flow rate is the same. Of course, it’s the same with electricity. Go through each of your DC and AC loads and add something into the “Estimated Hours Used Per Day” column (column C) for each. We can start with that cooktop which was a monster firehouse of consumption. However, if you only use it for 5 minutes it makes a big difference. This is why the answer to the original question is not universal. Some people cook a lot, some people don’t cook at all. So each electrical system and battery bank needs to be customized to your particular needs. Everything should be entered in hours. So, in the case of the cooktop, we need to divide 5 minutes by 60 to arrive at .08 of one hour. Let’s do the refrigerator next. This is tricky because there are a ton of factors that determine how often the refrigerator is going to be running. How hot is it in the van, how often are you opening the door, how much stuff is in there, etc? In this example, we’re estimating for an Isotherm Cruise 130. According to the manufacturer, the “average” draw of this model is 34 amps a day. If we divide that by 24 it comes out to be 1.5 amps per hour on average. So, that’s what we’ll use. It will be running all the time so we’ll use 24 in the hour column. Now check this out. That firehose of electrons, the cooktop only consumes a bit over 12 amp hours per day in this estimate. Meanwhile, the fridge, which is a drip by comparison (1.5 amps), is predicted to use nearly three times as much energy at 36 amp hours. This illustrates how important run time is. And, getting back to the original question: how many hours can I run my AC off my batteries? Let’s reverse the question for a minute like you’ve done with the other loads. How long do you want to run that AC every day and what is the flow rate or energy utilization of the AC? And, well, it gets even more complicated. What KIND of AC unit are you going to have in your van? To keep this complex answer as simple as possible, we’ll narrow this down to two choices: a traditional, RV, style, 120 volt AC rooftop unit (think Coleman, Dometic, etc.) or a newer, 12 volt DC rooftop unit (think Mabru, Dometic RTX 2000, etc.). If you dive into the specs of these options (check out our comparison sheet), the 120 volt AC models use right around TWICE the amount of power as a 12 volt model. But, the 12 volt options are also somewhere around TWICE the cost. Despite that, when you consider the cost of batteries, they tend to be a better value. So, let’s consider a Mabru, 12,000 BTU 12 volt unit. It uses anywhere between 22 and 55 amps depending on the cooling mode and fan speed. Let’s plan for a hot day where we will be running it on high overnight. But, our van is insulated, we have window coverings and we’ve set the thermostat to a reasonable temp. So, it won’t be running constantly all night. How often will it cycle on/off? Of course, it’s impossible to know for sure but let’s say the compressor is running about half the time. So, we’ll put 55 amps into the amp draw and 4 hours into the time column (half an eight-hour night). That totals 220 amp hours in a single day. There’s one version of the answer about air conditioners… But there is more! Consumption Totals Once you put in the time values for all your loads you’re halfway done. Ha ha, not really – you’re a bit more than halfway done. Told you this was a lot of work! At this point you know how much power your system is going to use – you can see in the bottom table (totals table) in the sheet. Look for the row called “Total Estimated Daily Consumption (Amp Hours)”. You can use this number to estimate how many batteries you need. In the first example sheet (named “Ex. 1: 600 Watts Solar, Moderate Driving, 12v AC “) the total consumption (before any of your customizations) was 358 amp hours per day. Recharging However, before you rush out and buy 400 amp hours of battery, let’s talk about recharging. How do you refill your empty tank? The next exercise is to model your charging sources. In a van, it’s very common to have 3x of these: solar, alternator charging of some kind when driving and shore power which is when you’re connected to the grid at a house or campground and can use that utility power to charge your batteries. Therefore, we’ve provided a row for each of these methods. We recommend that your van have all three. So, let’s start with solar and make it as simple as possible by ignoring all the real-world complexity of solar systems that affect their performance such as time of day, time of year, how cloudy it is, angles, how dirty or clean or panels are, and so on. We’ll use a simple rule of thumb for solar charging: for every 100 watts of panels you have on your roof, we’ll assume 5 amps of charging output to the batteries. So, if you have 400 watts of solar, you can enter 20 amps for that charging source. Of course, you’re welcome to do a more nuanced calculation here if you happen to have a very good idea of the places and light conditions you’ll be traveling in and knowledge of the panels you’ll be using. Just like loads, the amount of time you’re charging makes a huge difference! In this example, we’ll assume we’re parked in the full sun while we’re off at the beach all day and enter 8 hours which will produce an estimated 160 amp hours of power to charge the battery bank. The second way most people charge is with their vehicle’s alternator. We have a bunch of example power systems on our blog that you can take a look at. The most common options are either using one or more DC-DC chargers. The Victron Energy Orion DC-DC chargers can charge at up to 30 amps and most of our customers use two of them in parallel for 60 amps of charging. Blog update 2025: one or two Victron Orion XS 50 DC-DC converters is a great choice. Typically you don’t want to exceed 60 amps or 45% of your vehicle alternator’s rating. This is a substantial charge while not overtaxing your vehicle alternator. In fact, even if you use a single DC charger, that’s typically more charging current than having 400 watts of solar! In our example sheet, we’ll use two of these (60 amps) and expect to drive for 3 hours each day. Finally, so-called shore power which is whenever you can plug your rig into utility power. Often this is at a house or a campground. Remember that inverter we talked about that converts 12 volt DC power from your battery into 120 volt AC power for household-style loads? Often these things have a charger component that does the opposite – takes the utility power and converts it into some flavor of 12 volt DC power to charge your batteries. These are called inverter/chargers and we definitely recommend your inverter has this feature. Our most popular inverter/charger is the Victron Energy MultiPlus 12/3000/120 which can recharge your batteries at up to 120 amps! Notice how the charging capacity ramps up with each of these in this hypothetical example with solar being the sort of drip and shore power being more like the firehose. However, most of our customers prefer to stay off grid (boondock). For this reason, our example sheets have 120 in the amps column but zero into the time column. But, if your adventures lead to places with hookups, shore power can be a tremendously powerful charging source – even if it’s only once in a while. A Delicate Balance Now that we know about our loads (water going out) and our charging sources (how we refill), we can see how they balance out! In our first example sheet (again, before any changes were made), our expected daily utilization is about 62 amp hours less than our expected daily charging. That’s pretty good. If you see the opposite, where you’re using more power than you’re recharging, that is where your batteries come in. You want to size the capacity of your battery bank so that it is larger then your daily loads. If you expect your charging sources to be more variable (some sunny days, some days with less driving) you may want to have a larger battery bank to compensate and allow for these flutuations. Typically in a camper van power system a battery bank is comprised of two or more 12 volt batteries that are identical wired up in parallel. This method of creating the “bank” keeps the voltages the same but adds up the amp hour storage capacity. In the example described in the first sheet, we might use 2x or 3x of the Victron Smart 200 amp hour batteries to create a nominal 12 volt battery bank with 400 or 600 amp hour of storage capacity. Another reason to use multiple batteries is to ensure that your “bank” is capable of running your heaviest loads. Lithium batteries have a “maximum continuous discharge” rating that is often in the 50 to 100 amps range. Combining batteries together into a bank allows you combine this specification as well. So, if you have 3x batteries, each capable of 100 amps of continuous discharge, the combined bank of batteries would enable a maximum continuous discharge of 300 amps. Consider a 3000 watt inverter – if you max that out, you’d be looking at around 235 amps. That means the same batteries combined into a bank of 2x batteries wouldn’t provide enough juice to run that continously but 3x batteries would. While lithium batteries are a lot more resiliant to being discharged deeply compared to older lead acid/AGM batteries, most manufacturers recommend keeping your batteries above 20% state of charge to ensure the longest lifespan. So, if you have a battery that’s rated for 100 amp hours, you should consider only using 80 amp hours in your calculations. Going back to the water analogy, you could simply add a bigger water tank so that you can go longer without refilling or, in this case, recharging. But, the more balanced your consumption is with your utilization, the less you’ll have to worry about power. One of the key things to take away is that simply adding batteries for additional capacity isn’t a sustainable option without recharging sources. Now that you have a reasonable idea of what a day in the life of your power looks like, the last big question is how you’ll be using the rig over time. Are most days the same? Do you expect to drive a lot on certain days for additional alternator charging? Perhaps you expect to be at a campground or back at your stationary house every few days so you can use shore power to recharge your rig every night? There are so many unique scenarios. With the information you know from your load calculation, you can project how these scenarios would play out. Ultimately, these scenarios give you the insight you need to size your battery bank. Obviously, it’s best to have a little margin so that if your projections are wrong you have some extra juice. Another tip is to consider leaving space for one more of your chosen batteries. If you do find yourself with an energy deficit regularly, wiring in another battery is really simple if you have the space. Dedicated Secondary Alternators for High Power Recharging As battery banks get larger and larger an increasingly popular option is to add a secondary, dedicated charging alternator to your rig. So, instead of using DC-DC chargers that top out at 60 amps of charging to protect the vehicle alternator, you bolt on another high-current alternator from a company like Nations. These charge at anywhere between 120 to 200+ amps depending on your vehicle and the RPMs of the engine which means they can recharge large battery banks in a few hours. You can see the effect of this in the third sheet in our example load calculations (named “Ex. 3: No Solar, Driving w/ 2nd Alternator, 12v AC”). Next Steps If you made it this far and your head has not exploded, you rock and you’re a good candidate for installing your own DIY electrical system. We have a ton more information on our blog – many of which were linked to from this post. If you stopped reading because your head was about to explode, we have real people to talk to. Consider reaching out!
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