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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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Tech Deep Dive - Wakespeed WS500 Regulator
This post includes an extensive deep dive video with Wakespeed founders, Al Thomason and Rick Jones facilitated by Zach from Vanlife Outfitters and Jesse from Valley Hi vans. In addition, we’ve summarized some of the common questions we get about this amazing product in this post. We feature the Wakespeed in our secondary alternator example wiring diagram and best price product bundle. How is the Wakespeed WS500 regulator superior to something like a Balmar regulator? What really sets the Wakespeed apart is its ability to use voltage, current, and temperature signals to regulate charging rather than only voltage compared to something like a Balmar regulator. Additionally, the Wakespeed can monitor these signals digitally when used with CAN-connected batteries such as Lithonics and Victron Smart batteries. There are many other unique features but this foundational difference is key! What is a CAN bus and how does it work in a system with a secondary alternator with a Wakespeed regulator? 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 Blog update 2025: Victron NG batteries (paired with a BMS and Cerbo GX). There are two versions of the Wakespeed WS500 regulator. What is the difference between the “white box” and “black box” versions of the regulator? The white box Wakespeed WS500 has RJ45 CAN bus connection ports and the black box does not. In both cases, the wiring harness used with the Wakespeed has a standard CAN connection. So, if you have the white box, you have two options for CAN connectivity whereas the black box simplifies this to only one. Which version you use is typically determined by which type of CAN-connected battery you have in your system. If you’re using Lithonics batteries, you would normally use the black box version since you don’t need the RJ45 connections. In a Victron system with a Lynx Smart BMS and a Cerbo GX, you’d normally use the white box since the Victron equipment communicates CAN through the Victron VE.Can standard which uses RJ45 connections. Note: in early 2024, the formerly “white box” version of the Wakespeed regulator starting shipping with a black, plastic case. Blog update 2025: all of our secondary alternator kits include the latest generation WS500 Pro regulator. When using Victron Smart NG batteries with the Wakespeed, you’ll need the “Wakespeed to Victron” crossover cable to adapt the pin configuration that Wakespeed uses on their RJ45 connections to those used by Victron Energy on theirs. In Victron systems, you’ll want to be sure the Wakespeed is running firmware version 2.5.0 (or higher) and the Cerbo GX has Venus OS 2.90 (or higher). The Wakespeed guide for Victron systems is a great resource to check out. When using Lithonics batteries with the “black box” version of the Wakespeed, you’ll need a few adapter cables. The image above shows a 2x battery set up with the Wakespeed “CAN Bus Y Adapter cable” and a Litihonics “Wakespeed/Iongauge Integration Harness”. What brands of lithium batteries have been qualified to work correctly (and safely) with the Wakespeed WS500 regulator and why are only certain brands supported? You can visit the “technical” 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 manufactuer 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. How do you use the Wakespeed WS500 regulator with “legacy” batteries that don’t have a CAN bus connection including “drop-in replacement” batteries with internal BMS like Battleborn lithium batteries? Unlike CAN-connected batteries where the voltage, temperature, and current are available digitally, systems that use internal BMS batteries without CAN connections like Battleborn need an analog shunt for current monitoring and a battery temperature sensor so that these signals, along with voltage can be used by the regulator for optimal charging. Currently, Battleborn is the only brand of this type of battery that is qualified by Wakespeed. In addition to using a qualified battery, you should be sure to design your system with at least 3x batteries so that if the BMS in one or more of the batteries disconnects from charging there is at least one or two remaining online to absorb the charging current so there isn’t a “load dump” situation. What is the difference between the standard wiring harness and the “van harness”? The Wakespeed WS500 regulator has various wiring harnesses that plug into the large port on the bottom of the regulator. These variations are designed to accommodate different types of installations. The most commonly used harnesses are described below. The standard harness is most often used in marine environments where the regulator is placed near the engine. It includes all of the connections/wires detailed in the quick start guide. The so-called, van harness is designed for, you guessed it, vans! It assumes that the Wakespeed will be placed near the rest of the van’s electrical system components in the rear area of the van so it has a long (approximately 27′) leg that runs up to the alternator location and another long (approximately 17′) leg that runs to the vehicle’s ignition switch circuit (brown wire). Check out our other blog post/video that details every connection on the Wakespeed WS500 van harness. FREE Camper Van Power System Resources & Wiring Diagrams If you’re confused about your DIY camper van electrical or solar system, you’ve come to the right place. We have tons of resources including blog posts, videos and detailed example wiring diagrams (see below), Our “choosing a system” page offers some additional advice and includes an example load calculation that you can use. Please consider purchasing your power system equipment from our store. Our bundles offer great pricing (yeah, better than Amazon), free shipping and you’ll have access to expert support and you’ll be supporting our ability to create more content! Finally, there are a few things that we don’t sell in our store (yet!) that you might need so we keep a list of these products in this Google Sheet of recommended camper van products.
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Vanlife Electrical System Tour Video - Victron Energy Components with External BMS
In this short video we go over the components of a camper van electrical system that we installed into a customer’s van. She brought us the cabinet and we filled it up with a bunch of blue boxes from Victron Energy to create a powerful, off-grid capable power system for her van that charges with three sources: solar, from the vehicle alternator when driving and when connected to shore power. This system uses Victron Energy Smart Lithium batteries with an external BMS (Lynx Smart BMS). We have another blog post that is a deep dive on an example system like this including a free example wiring diagram and we have best price product bundle in our store if you want to install a system like this into your van! FREE Camper Van Power System Resources & Wiring Diagrams If you’re confused about your DIY camper van electrical or solar system, you’ve come to the right place. We have tons of resources including blog posts, videos and detailed example wiring diagrams (see below). Our “choosing a system” page offers some additional advice and includes an example load calculation that you can use. Below are some of our example power systems for camper vans/RVs. The Victron-based systems all have a corresponding blog post, free detailed PDF example wiring diagram, and a corresponding best price product bundle. Ultimately, you’ll probably customize your system to your particular needs and perhaps combine ideas from one or more of the example systems. A baseline camper van electrical system that uses lithium batteries with internal battery management systems (BMS) such as a Victron SuperPack, Battleborn, SOK, etc. This is our most affordable and simple system as well as the most DIY friendly. A more advanced camper van electrical system that uses Victron Smart lithium batteries with an external BMS and a Cerbo GX for monitoring. This system is a bit more complex and more costly, but adds features and allows for more battery storage in the same physical footprint. If you use the Victron Lynx Smart BMS you can upgrade to a dedicated secondary alternator with a Wakespeed regulator in the future. A super powerful (fast-charging) system that uses a dedicated secondary alternator. This system is the most expensive but also the most off-grid capable. We also have a 48-volt version of this system! We also have a power system accessories bundle that has all the circuit protection, shore power, distribution, and wiring you’ll likely need. Please consider purchasing your power system equipment from our store. Our bundles offer great pricing (yeah, better than Amazon), free shipping and you’ll have access to expert support and you’ll be supporting our ability to create more content! Finally, there are a few things that we don’t sell in our store (yet!) that you might need so we keep a list of these products in this Google Sheet of recommended camper van products.
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Camper Van Electrical System with Victron Smart Batteries and External BMS
Jump To Wiring Diagram Download Best Price Product Bundle Overview In this post we’re going to dive into how to wire up a Victron Energy based camper van electrical system that uses their Smart lithium batteries which require an external BMS and provide two free wiring diagrams. The Smart lithium batteries are available in a variety of sizes/capacities but we prefer the 200 amp hour and 330 amp hour versions. Update 2025: Victron how offers NG battery systems that have replaced the Smart systems. You might also want to check out this video tour of a system based off this design. FREE Camper Van Power System Resources & Wiring Diagrams If you’re confused about your DIY camper van electrical or solar system, you’ve come to the right place. We have tons of resources including blog posts, videos and detailed example wiring diagrams (see below), Our “choosing a system” page offers some additional advice and includes an example load calculation that you can use. First, what is a BMS? In short, Battery Management Systems (BMS) listen to the batteries and are the device in charge of protecting them from being overly charged (over voltage), too discharged (under voltage), too hot or too cold. Want to know more? Check out this deep dive video – but then remember to come back! External BMS Trade Offs In contrast to Victron’s SuperPack batteries or other popular battery brands like SOK that have built-in BMS systems, Victron’s Smart batteries use an external BMS. Advantages 1) You can fit more power into a smaller space. The footprint of a Smart battery is about half that of an internal BMS SuperPack battery. So, you can fit 200 amp hours of storage into the same physical space as a 100 amp hour battery. 2) Higher current. The external BMS Smart batteries have substantially higher maximum continuous charging and discharging specifications. The SuperPack batteries (internal BMS) are rated at 100 amps continuous for charging and discharging whereas the Smart batteries (external BMS) can handle twice that (200 amps continuous). This allows the batteries to be charged rapidly if you have a high-current charging source (like a secondary alternator) and, probably more importantly in the context of vans, it allows you to run large loads, like a MultiPlus inverter/charger, off fewer batteries. Consider that the most popular Victron inverter/charger (the MultiPlus 12/3000/120) pulls well over 200 amps when outputting 3000 watts of AC and can go over 400 amps briefly when surging to 6000 of inverted AC. Often these inverters are tasked with running an induction cooktop and a microwave plus other loads simultaneously. If you are using batteries that max out at 100 amps continuous discharge, you would need 4x of them, wired in parallel to support that load. Switch to the external BMS, Smart lithium batteries and you only need 2x. 3) More finite control. Externalizing the BMS and using the types of devices that we discuss in this post enable much more control on how your power system will respond to the battery state. Here again, this adds complexity, but also adds features. For some folks this will be an advantage and for others, well, not so much. 4) If your BMS dies, you don’t have to replace the battery. As you probably know already, batteries are one of the most expensive parts of a power system. Externalizing the BMS allows you to replace that single part if it dies/breaks. If the BMS is built into the batteries you may have to replace the entire battery. 5) Higher voltage systems. Most of our customers prefer the simplicity of a 12 volt system. But, if you want to install a 48 volt (or higher) system, an external BMS can accommodate that in a way the built-in batteries may not. VE.Bus BMS vs. Lynx Smart BMS When using Victron Energy’s Smart Lithium batteries that require an external BMS, we typically use either the “simple” and affordable VE.Bus BMS or, in some cases, the more expensive but “fancier” (more feature-rich) Lynx Smart BMS. This post covers both and includes a free wiring diagram for both as well. Both BMS options accomplish the main goal of protecting the battery. The Lynx Smart BMS has the following advanced features: It has an integrated shunt for battery monitoring so you don’t need a BMV-712 or SmartShunt in the system. It has a built-in 500 amp “contactor” that can disconnect charging/discharging when triggered by the batteries (temp/voltage) to anything that is wired up downstream (wired to the Lynx Distributor that is electrically connected to the “output” of this contactor”. I’ll explain how this is beneficial toward the end of the post. As suggested by its name, the Lynx Smart BMS is part of the Lynx “system”. If you take a look at the photo below you can see how the Lynx Smart BMS bolts onto the Lynx Distributor(s) to create a smart and tidy approach to your entire 12 volt DC bus. By using a Lynx Smart BMS with a Lynx Distributor you can “turn on” the features on the Lynx Distributor that you don’t get without it. There is a RJ10 (phone style) cable included with the Lynx Distributor that you can connect between it and the Lynx Smart BMS. When you do so, the Lynx Distributor will communicate if there is a blown fuse on any of its connections. Bluetooth connectivity. Anything made by Victron Energy with the word “Smart” in the name means that it has a Bluetooth connection that you can use with their VictronConnect app. You get a ton of info and configuration ability from the VictronConnect app with the Lynx Smart BMS including the ability to name each connection on the Lynx Distributor(s) (i.e.: “MultiPlus” or “Solar”) and notifications sent to the app and Cerbo GX if a fuse blows, etc. It has VE.Can connectivity to a Cerbo GX so that you can add CAN bus communication for things like DVCC (more on that below) or secondary alternator charging with something like a Wakespeed WS500 regulator. Wiring Up The Batteries Victron Energy’s Smart lithium batteries have two short, black wires attached to them with 3-conductor M8 connectors. You’ll begin by wiring them together (daisy chained) with these short wires and then use an extension cord (available in various lengths) to wire the string of batteries to the BMS you are using. VE.Bus BMS – Controlling Charging/Discharging On Behalf of the Battery The VE.Bus BMS can control a MultiPlus inverter/charger – which is both a charging and discharging device – through the VE.Bus. There is a VE.Bus connector on the BMS and also on the MultiPlus. This is an RJ45 (ethernet-style) connection. The BMS also has so-called “allow to charge (ATC)” and “allow to discharge (ATD)” connections. These are basically relays that are “normally closed” allowing voltage to flow to the device they are connected to as a sort of “signal”. When the batteries “tell” the BMS they should not be charged or discharged the respective relay “opens” which stops the flow of electricity through the relay. In a van power system, the allow to charge (ATC) is typically used for Orion DC-DC chargers and MPPT solar charge controllers. In the case of the Orion’s, they have something called “engine shutdown detection” which is a feature where they monitor the voltage of the vehicle battery (that they are wired to for charging). When it rises to a certain threshold (around 14 volts but can be adjusted in the settings), it assumes the vehicle is running and, therefore, the vehicle alternator is providing current to the vehicle battery which would mean that it’s safe to charge the “house” batteries without depleting the vehicle battery. When they sense this, the Orion’s turn themselves on and start charging your house batteries. This is awesome, easy and reliable “most of the time”, but suppose the BMS is “told” by the batteries that they shouldn’t be charged (perhaps it’s too cold)? In that scenario we’d want to override this automatic detection. Well, the Orion DC-DC chargers have remote terminals that can be wired up to a toggle switch in order to manually switch them on or off. The BMS can use this remote switch to turn off the unit when necessary – you simply wire up the ATC relay to the remote “H” (high) terminal. In normal circumstances this relay is “closed” (providing signal voltage) and when the BMS (on behalf of the batteries) decides the batteries should not be charged (too cold in our example), that relay “opens” which acts like the toggle switch being turned off thus disabling charging. Below is a photo of two 30 amp Orion DC-DC chargers used in a system. They are wired in parallel for charging at 60 amps total as shown in the example wiring diagrams. The ATC wiring is circled in yellow. Allow To Charge (ATC) With Victron SmartSolar MPPT Controllers There are two ways for the BMS to control the charging output of a Victron Energy SmartSolar controller (such as this 100/50 model shown in our example wiring diagram). They typically come with a VE.Direct port. In systems where using a GX device such as the Cerbo GX paired up with a GX Touch 50 screen, you’ll want to use this VE.Direct port to connect the controller up to the Cerbo GX so that its data can flow into that system. If you’re not using a GX device, you can instead use that VE.Direct port on the solar charge controller similar to the “remote” terminals on an Orion DC-DC charger with the so-called “Victron Energy VE.Direct Non-Inverting Remote On-Off Cable“. One side of that cable is wired to the allow to charge relay on the BMS and the other side has a VE.Direct style plug that can connect up to the solar charge controllers. If you are using a GX device (like our example wiring diagram), you can use something called a Smart BatteryProtect. These are basically high current relays that can turn off the power flowing through them when triggered by something such a BMS (or wired to a switch, etc.). They come in various current ratings but we typically use the 100 amp version. These Smart BatteryProtects (SBPs) have the same kind of remote switch terminals that the Orion DC-DC chargers do which allows you to wire the allow to charge (ATC) relay on the BMS to a similar “H” connection on the SBP’s remote terminals to disable any charging sources connected to/through it. So, in our VE.Bus BMS sample wiring diagram, we show the charging outputs from the solar charge controllers wired up to a SBP and then to the positive bus (Lynx Distributor). Other Loads – Allow to Discharge (ATD) If your charging device doesn’t have anything that can respond to an ATC signal or some other “fancier” mechanism such as the other Victron communication protocols (VE.Bus, VE.Can, etc.), you can use something called a Smart BatteryProtect. These are basically high current relays that can turn off power flowing through them when triggered by a BMS. They come in various current ratings but we typically use the 100 amp version. These Smart BatteryProtects (SBPs) have the same kind of remote switch terminals. So, just like an Orion DC-DC charger, where you could wire up a toggle switch to control their on/off state (allowing current to flow or not), you can also use wire their “H” (high) remote terminal to a BMS ATC (allow to charge) relay. Other Loads – Allow to Discharge (ATD) As mentioned earlier, there are also times where the battery “tells” the BMS that it shouldn’t be discharged as well – typically when the battery is deeply discharged (low voltage) and would be damaged if the loads continue to discharge the battery (if you keep running your refrigerator/lights/fan). The Smart BatteryProtects (SBPs) are useful in this scenario as well. In our example system we show a SBP wired between the Lynx Distributor (DC positive and negative bus bar) and the 12 volt DC load center/fuse box. Then the BMS’ allow to discharge (ATC) relay signal wire is connected to the “H” (high) side of the SBP remote terminal. In this way, the BMS (again, on behalf of the batteries) can disconnect these loads when necessary. Note, if you’re using a Cerbo GX in a system with a VE.Bus BMS, connect the power supply (12VDC positive) to the ower in V+ on the Cerbo GX to the “load disconnect” (ATD) terminal on the VE.Bus BMS. Then, for the VE.Bus connection, use the port “MultiPlus/Quattro” on the VE.Bus BMS – don’t use the “remote panel” port. Using a Lynx Smart BMS We’ve already discussed some of the advantages (extra features) of the Lynx Smart BMS. Now let’s dive into how using it in a power system differs from the VE.Bus BMS. Again, we’re providing an example wiring diagram of a system using both BMS options! The first important thing is that a Lynx Smart BMS needs to be paired up with a “GX Device”. In almost all cases, that GX device would be Victron’s Cerbo GX (we’re working on another blog post about that!). The Lynx SmartBMS is connected via a VE.Can connection to the Cerbo GX which enables some new magic: DVCC… DVCC – Distributed Voltage and Current Control In short, DVCC allows the Lynx Smart BMS to control charging and discharging (as well as charging parameters) through the Cerbo GX on the DVCC capable devices. In a typical van power system those would be a MultiPlus inverter/charger, Victron MPPT solar charge controllers and, perhaps a Wakespeed regulator used with a secondary alternator. In Victron’s words:“Enabling DVCC changes a GX device from a passive monitor into an active controller. The available features and effects of enabling DVCC depend on the type of battery used. The effect also depends on the installed Victron components and their configuration.” With DVCC enabled, the Lynx Smart BMS will automatically configure the “charging profile” for the batteries (adjusts the discharge current, charge current, charge voltage, etc.). Without DVCC, the installer must manually configure all the charging sources in their system. A typical van system will have at least a few charging sources: an inverter/charger, DC-DC chargers and solar charge controllers. Most Victron charging devices can be configured using VictronConnect via Bluetooth. However, MultiPlus inverter/chargers cannot be configured with Bluetooth – instead you must configure via the “VE.Bus” by using a MK3-USB adapter. To further complicate matters, when using a VE.Bus BMS, MultiPlus inverter/charges must be configured using VE.Configure including adding an “assistant” (detailed in this blog post). More about DVCC:https://www.victronenergy.com/media/pg/CCGX/en/dvcc—distributed-voltage-and-current-control.html So, DVCC simplifies the configuration of DVCC compatible chargers (“smart things”). But we still need to consider the “dumb things” that don’t have communication ports (VE.Direct/VE.Can/VE.Bus, etc.). In a van power system, that is stuff like our 12 volt DC loads (fuse box/load center) that were run through the Smart BatteryProtect when using the VE.Bus BMS. The Orion DC-DC charges are also “dumb” in this sense. Remember that one of the features of the Lynx Smart BMS was a 500 amp “contactor”? Here’s where that comes into play. Below (again) is the same illustration we showed earlier detailing how you might wire a system where your batteries are wired in parallel by connecting each to a Lynx Power In (far left). This allows up to 4x batteries to be connected to a combination DC positive and DC negative bus bars. In the middle of the illustration is the Lynx Smart BMS which is electrically connected to the Lynx Distributor on the left (battery connections) and passes their current onto the BMS. Inside the Lynx Smart BMS is the shunt that will monitor your electrical use and report on the state of your battery. Also inside there is that 500 amp “contactor”. Then, on the right side a second Lynx Distributor used for the loads and charging sources. This is also electrically connected to the Lynx Smart BMS and it’s where you’d wire up your inverter/charger, solar controller output, DC-DC charger output, etc. So, if the contactor in the Lynx Smart BMS “opens” the power cannot flow to the right-side Lynx Distributor (loads and charging sources). Keen readers may be realizing something important: both “smart” and “dumb” loads/charging sources are wired to that Lynx Distributor. Since the contactor is controlled by the BMS (well, it is the BMS), it can, therefore (by itself), disconnect charging and loads when the battery “tells” it to. Does this mean you don’t need to use a Smart BatteryProtect for your 12 volt DC loads (wired to the ATD relay) or to wire up the Orion DC-DC chargers to the ATC relay through their remote terminals? Yes, technically it does if you want to keep things as simple as possible. However, the Lynx Smart BMS does have the same kind of ATC and ATD relays that the VE.Bus BMS does but the reason you might want to use them is somewhat nuanced… The contactor in the BMS is triggered to open (cut off power) when the battery cell voltage (there are many cells in each battery that generate the nominal 12 volts) reaches 2.6 volts (a deeply discharged battery bank). Meanwhile the ATD relay would open at the slightly higher battery cell voltage of 2.8 volts. Thus, by wiring up your ATD to something like a Smart BatteryProtect, you can stagger the system shutdown so that you can turn off many of your “non-essential” loads (those connected via a Smart BatteryProtect) prior to the entire system being disabled. So, perhaps you cut off your loads like a fridge/fan/etc. but want to keep monitoring like the Cerbo GX running longer. Or, in marine applications, the use case is a bit more clear – it’s fine to disable the fridge or some lights in a situation where the batteries are dangerously low, but the navigation equipment should continue to operate while we figure out how to get some charge into these batteries! Example Wiring Diagrams One thing we always tell our customers is that there are MANY ways to wire up an electrical system that is safe and functional. Even when you use most of the same or similar components, you can approach the configuration slightly differently. There are a ton of considerations that lead to these small differences – everything from preference to space constraints to budget. 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 External BMS Wiring Diagram for our example wiring corresponding with this blog post.
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Programming a Victron MultiPlus Inverter/Charger With a VE.Bus BMS
UPDATE – in October of 2021, Victron Energy released version 489 (xxxx489) of the firmware for MultiPlus inverter/chargers. According the release notes, if you use this firmware, “there is no need to use the VE.Bus BMS assistant anymore.” Below, in italics, are the notes regarding this, taken from the changelog file from Victron Energy. Using this new firmware results in practically the same behaviour as previously when using the Assistant. As soon as the Multi (or Quattro) sees the VE.Bus BMS, and the (new) checkbox called “Configured for VE.Bus BMS” is not checked yet, it will automatically configure itself. The settings then auto-configured are: The (new) ”Configured for VE.Bus BMS” setting is set, meaning that it will no longer charge in case it doesn’t see the VE.Bus BMS anymore. In more detail: it will go through passthrough when AC is present, and switches off if there is no AC BMS. This is a safety feature. Battery type is set to lithium Absorption voltage is set to 14.2V, Float to 13.5 Maximum absorption time to 60 minutes Charge curve fixed (but reduced float is disabled, the settings “repeated absorption time” and “repeated absorption interval” are changed but ignored) Storage mode is unchecked State of charge when bulk is finished: 95% Charge efficiency: 95% Temperature compensation is disabled. The recommended way to commission such system is to: update the firmware install and connect the VE.Bus BMS unplug the VE.Bus BMS and wait for the Multi to switch to passthrough/switch off. This step ensures that the Multi has properly detected the VE.Bus BMS. Reinsert the VE.Bus BMS. Finished, or optionally connect with VictronConnect and make the rest of the configuration. Related changes: The VE.Bus BMS Assistant, when installed on this new firmware, will issue a warning, that it needs no longer to be installed. (It will be harmless if it is). The ESS Assistant as well as some others, with integrated VE.Bus BMS functionality are updated and will work with both old firmware & new firmware. I recommending using the VictronConnect app to program/configure your Victron MultiPlus inverter/charger. We detail how to do that in this post. So, you can go through that process and then come back here for one additional step required when using a VE.Bus BMS – the addition of an “assistant” for the BMS. This BMS “assistant” is specifically for Victron lithium batteries using the VE.Bus BMS. It allows the BMS to control the MultiPlus inverting and charging. If you have a remote control panel it will work like normal but can be “overridden” by the BMS. Unfortunately, at this time, you cannot add assistants with VictronConnect. Instead you’ll need to use the older, VEConfigure app for Windows. However, just like configuring with VictronConnect, you’ll use the same MK3 to USB interface for connecting your computer to the MultiPlus. This video from Victron is a great overview to using VEConfigure and setting it up with your computer. I recommend checking it out before proceeding. Once you’re connected to your MultiPlus with VEConfigure you’ll want to navigate to the “assistants” tab and then click on the “add assistant” button which will open a menu of available assistants. Choose the “VE.Bus BMS” assistant from the menu. Next, you can press on the “start assistant” button and use the “next arrow” button to proceed through the screens as they are shown below. Once you receive that final confirmation screen you can dismiss it with the “OK” button and you’re done! Note, after you’ve added the BMS “assistant”, the red “low battery” led will flash when the unit is powered on and won’t work until it “sees” the VE.BMS on the VE.Bus. Also, you will not be able to use VictronConnect after you’ve added the “assistant” – instead you’ll have to use VEConfigure. Please consider purchasing your power system equipment from our store. Our bundles offer great pricing (yeah, better than Amazon), free shipping and you’ll have access to expert support and you’ll be supporting our ability to create more content!
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Configuring a Victron MultiPlus Inverter/Charger
This post was originally published in 2021. 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. Why Program? In most cases you’ll need (or want) to program/configure your Victron MultiPlus inverter/charger after it’s installed into your van. For instance, since the MultiPlus comes from the factory setup to charge AGM type batteries, if you have lithium batteries, you’ll want to, at least, change the charger functionality to charge your batteries correctly. If you have a system that uses Victron Energy Smart or NG lithium batteries with a Lynx Smart or NG BMS, such as ones like our secondary alternator kit example, DVCC will take over and make sure your batteries are charged correctly from the MultiPlus and any other Victron charger that is digitally connected to a Cerbo GX/BMS such as a Smart Solar MPPT charge controller that is connected via VE.Direct. This includes Let’s Start With The Defaults The table below shows how the settings are configured by default when you get the unit. Inverter frequency 60Hz Input frequency range 45-65Hz Input voltage range 94-143VAC Inverter voltage 120VAC Stand-alone/parallel/3-phase stand-alone AES (Automatic Economy Switch) OFF Ground relay ON Charger ON/OFF ON Battery charge curve four-stage adaptive with BatterySafe mode Charging current 75% of the maximum charging current Battery type Gel deep discharge Automatic equalization charging OFF Absorption voltage 14.4V Absorption time up to 8 hours Float voltage 13.8V Storage voltage 13.2V Repeated absorption time 1 hour Absorption repeat interval 7 days Bulk protection ON AC input current limit 50A Dynamic current limiter OFF WeakAC OFF BoostFactor 2 Programmable relay alarm function PowerAssist ON What You’ll Need 1) A Victron MK3-USB interface. This small device allows you to connect to the VE.Bus on the MultiPlus with your computer (or compatible mobile device) using USB. You’ll (of course) need the computer or mobile device. I recommend a computer if you have it. You’ll connect a standard ethernet cable with RJ45 connectors (must be a “straight-through” not “crossover” type cable which most are) from either of the two VE.Bus connections on your MultiPlus to the corresponding connection on the MK3-USB interface and then connect the USB connection on the MK3-USB to your computer/mobile device. One small tip, it’s really difficult to remove the RJ45 connection on the ethernet cable from the VE.Bus connection on the inverter/charger. So, you might consider breaking off the “clip” on that connector so it can pull out without releasing the clip. Chances are you have a broken one laying around anyway! Another thing to know is that you’ll want to be sure that the MK3-USB connected to computer/device you’re using for the configuration is the ONLY device on the VE.Bus. If you have your MultiPlus connected to a remote panel or Cerbo GX you’ll want to disconnect those during the configuration. Windows ships with a compatible driver for both the MK3-USB interface so you typically don’t need to install a driver. In case you do have issues connecting via USB, we recommend manually installing the device with the driver you can download from their software downloads page. 2) VictronConnect software which you can either download from the Victron website or install from the Play Store for Android or Apple App Store for iOS. Note: iDevices does not support USB OTG (On The Go), so you must use either a Windows PC or an Android device with the MK3-USB interface. Other Bluetooth devices work well using iDevices using VictronConnect. Note: Victron also makes a VE.Bus Smart Dongle that basically adds Bluetooth connectivity/control to the MultiPlus interter/chargers. It connects to the same VE.Bus with an ethernet cable. When you connect to the inverter with VictronConnect via Bluetooth using this dongle you can see all of the same reporting information as well as control the state of the inverter (on/off/charger only mode, etc.) but the advanced settings (configuration) is not available unless. Because of this, you need the Mk3-USB interface for the kind of programming this post discusses. However, you might want the Smart Dongle to control and monitor your inverter/charger when you’re using your van on a day-to-day basis. Are these dongles and interfaces confusing? Check out our blog post for Victron Energy Dongles: Explained! Alternatively, if you have a Cerbo device such as the Cerbo GX that is connected to Victron’s cloud service (VRM) and it’s configured correctly, you can actually use VRM’s remote configure option as shown in this video. (2026) And here's a newer blog post covering how to remotely Configure your Victron system with VRM The following screenshot from Victron shows the 3x ways to connect to a Victron product (including the MultiPlus) If You’re Configuring an old-version (“compact”) MultiPlus 12/2000/80… There are some “dip switch quirks” when configuring the older-style “compact” MultiPlus 12/2000/80 unit. You must make sure that the #2 dip switch is “on” (switched to the right) and the others are off (switched to the left). The switches are located under the cover toward the top right of the circuit board. They are numbered from the top down. So the #2 dip switch is the second from the top as shown in the photo. You don’t need to bother with this on newer MultiPlus units including the newer version of the 12/2000/80 that begins with part number PMP (the older, “compact” version part number begins with CMP). Using VictronConnect & Updating Settings Now that everything is connected, be sure that your MultiPlus is powered on using it’s DC power connection to your battery bank and in “inverting” mode. Next launch the VictronConnect app. It should search the VE.Bus for devices and find your MultiPlus. When it does, you can click on it to open up the reporting. From there you click on the “gear” (settings) icon in the very top right part of the interface. A message will appear telling you that the settings are disabled with what amounts to a warning not to screw things up. It’s good advice… proceed with caution and be sure to reach out to a qualified electrician/engineer or your distributor/dealer with any questions or if you don’t feel confident programming the device. If you’d like to proceed, you can click on the “enable settings” link and enter the password zzz. If you’ve made it this far you’ll see five main “sections” of settings: general, grid, inverter, charger and AC input control. In the video below, we’ll go through some of the settings we normally change/set in our installations. You can refer to the built in “help” inside the VictronConnect for details on all the settings and what they do. Firmware Updates While you’re in these settings, you can click on the “three dots” menu at the very top right and then click on “product info” this will display the unit’s firmware version with a link to “update” if you’re not on the latest version. Lithionics or SOK Batteries The video shows the charging parameters recommended for Victron Energy SuperPack or Smart lithium batteries. Each battery maker has slightly different recommendations for charging their specific batteries. Additional Configuration Required When Using Victron Smart Lithium Batteries If you’re using Victron’s Smart batteries that do not have built in BMS, you need to have an external, VE.Bus BMS and, more than likely, some type of Smart BatteryProtect device on your “dumb” loads which are those 12 volt DC loads that don’t have any kind of “data bus” (no VE.Bus) or way to be “triggered” by the BMS to turn on/off discharging/charging. You can check out this blog post that details an example power system that uses the Smart batteries. In addition, you’re MultiPlus needs to be “aware” that it’s in a system that is using a VE.Bus BMS which requires the addition of what Victron calls an “assistant”. At the time I’m writing this post (April 2021), this additional programming/addition of “assistants” cannot be done with VictronConnect. Instead, you need to use the older VEConfigure software with the same MK3-USB interface. You can download VEConfigure as part of the VE Configuration Tools package (Windows only) on this page of Victron Energy’s website. I detail this extra programming for Victron batteries in another post. Using batteries that require an external BMS adds complexity so many DIY van builders prefer so-called “drop in replacement” type lithium batteries such as SOK or Epoch. This blog post details an example of a system using batteries with a built-in BMS. There are some pros and cons to the Victron approach vs. the “drop in replacement”/built-in BMS approach that I write about in this post.
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DIY Camper Van Electrical System Example (12V Internal BMS Batteries)
Example DIY Camper Van Electrical System Jump To Example Wiring Diagram Product Bundle For This System This post was originally published in September 2020 and is great for a system up to about 300-400 amp hours of battery storage. We update it occasionally. We highly recommend starting at this page to get a orientation on how to plan and design a mobile power system. You can also reach out to us at service@vanlifeoutfitters.com or call us at 754-444-8704 x2. This post includes a detailed wiring diagram and complete list of materials needed to put together a very reliable and robust electrical system for your camper van that is capable of extended off-grid adventures and powering just about anything you throw at it. FREE Camper Van Power System Resources & Wiring Diagrams If you’re confused about your DIY camper van electrical or solar system, you’ve come to the right place. We have tons of resources including blog posts, videos and detailed example wiring diagrams (see below). Our “choosing a system” page offers some additional advice and includes an example load calculation that you can use. Below are some of our example power systems for camper vans/RVs. The Victron-based systems all have a corresponding blog post, free detailed PDF example wiring diagram, and a corresponding best price product bundle. Ultimately, you’ll probably customize your system to your particular needs and perhaps combine ideas from one or more of the example systems. A baseline camper van electrical system (this blog!) that uses lithium batteries with internal battery management systems (BMS) such as Victron SuperPack, SOK, Epoch, Battleborn, etc. This is our most affordable and simple system as well as the most DIY friendly. A more advanced camper van electrical system that uses Victron Smart lithium batteries with an external BMS and a Cerbo GX for monitoring. This system is a bit more complex and more costly, but adds features and allows for more battery storage in the same physical footprint. If you use the Victron Lynx Smart BMS you can upgrade to a dedicated secondary alternator with a Wakespeed regulator in the future. A super powerful (fast-charging) system that uses a dedicated secondary alternator. This system is the most expensive but also the most off-grid capable. We also have 24-volt and 48-volt versions of this system! We also have a electrical system accessories bundle that has all the circuit protection, shore power, distribution, and wiring you’ll likely need, Please consider purchasing your power system equipment from our store. Our bundles offer great pricing (yeah, better than Amazon), free shipping and you’ll have access to expert support and you’ll be supporting our ability to create more content! Finally, there are a few things that we don’t sell in our store (yet!) that you might need so we keep a list of these products in this Google Sheet of recommended camper van products. Overview: 400 amp hours of lithium battery storage with built-in BMS 400 watts of rooftop solar 2400 watt inverter (up to 6000 watts surge) with 120 amp shore power charging capacity Integrated 12 volt DC and 120 volt AC load center 60 amps of alternator charging when driving/engine is running Optional pre-inverter shore power outlets Battery monitoring with Bluetooth It’s super important to realize that there are hundreds of ways of skinning this cat. How awful. We won’t be skinning cats and neither should you. Anyway, the point is that this information should be considered a guide not gospel. You certainly could build out this system exactly as detailed but I would recommend considering your particular needs and then adjusting accordingly. Also, wire lengths matter. This electrical diagram assumes that there is about a 20′ run from the vehicle battery back to the driver side wheel well where the “primary” electrical system is installed. What I mean by “primary” is most of the stuff you see on the wiring diagram – all the main parts but not the “branch circuits” that power the actual loads in the van like lights and fans, etc. It also assumes all those components are close together – not more than 5 (ish) feet of cable run between them. If your actual setup is different than this you need to adjust the wire gauge (AWG) accordingly. The Blue Sea Circuit Wizard is a great tool for understanding what gauge wire you need. You put in the load in amps, the length of the cable run and how long it will be running in minutes and it will tell you the correct gauge. I favor “over gauging” in general. Wire is pretty inexpensive relative to the other parts. In this wiring diagram I have also over gauged to keep it a bit more simple so that you don’t need so many types/gauges of wires and lugs and so on. Speaking of wiring… you’ll probably use wire loom to protect your wires when you run them in areas they might be damaged by rubbing against stuff. So, let me introduce you to this “wire loom insertion tool“. It’s pretty much a game changer. Why A 50 Amp Breaker?! With most 2000 or 3000 watt inverters you would match the shore power’s 30 amp inlet on the output side. However, Victron Multiplus inverters have a unique feature -they will actually supplement the utility power coming in from the shore power plug with their inverted power – up to 3000 additional watts. So, if you manage to have enough stuff running in your van to exceed the 30 amp service from the shore power, the inverter would actually fill in the gap instead of tripping the shore power breaker. So, while this is not likely to happen unless you’re running some kind of crazy loads in your rig, it’s important to provide circuit protection and adequate wiring “just in case”. Therefore this wiring diagram calls for a 50 amp breaker downstream from the inverter with 6 AWG wire instead of a more “typical” 30 amp breaker with 10 AWG wire. Inverter Wattage If you look closely at the specs of the Victron Multiplus inverters they don’t actually support continuous 2000 or 3000 watts respectively. This isn’t important but it can be a bit confusing because of how they’re named. The MultiPlus 12/3000/120 outputs 2400 watt continuous output at 77 degrees, 2200 watts at 104 degrees and surge up to 6000 watts. The MultiPlus 12/2000/80 outputs 1600 watt continuous output at 77 degrees, 1450 watts at 104 degrees and surges up to 4000 watts. Victron MultiPlus Inverter/Charger Configuation Once you get your system all wired up you’ll need to configure/program the MultiPlus to, at minimum, work with the batteries you’ve chosen and maybe tweak a few of the other settings. We have another post on how to do that. A Little Battery Update (January 2025)In addition to the complexity, the other pain point around electrical systems is how expensive they are. In particular, the leading brands of lithium batteries such as the Victron batteries we show in our example and other popular brands like Battleborn are very expensive – about $1,000 per 100 amp hours. It’s a classic sort of “pay for what you get” scenario and there are good reasons to purchase the highest quality components. For example, the are excellent quality, designed to last for many years with 10 year (!) warranties. But, the truth is that not every van build needs the very best batteries and there are well-made alternatives that are just about half the price! In some cases, having more capacity (amp hours of stored energy) may be better than more longevity. You can ask yourself, do I want to run the stuff in my van twice as long for a few years or half as long for a decade? Anyway, Will Prowse made an excellent video testing out well-built but lower cost lithium batteries that is worth checking out. One example is the SOK battery in our store. Wiring Diagrams 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 Internal BMS (Basic) Wiring Diagram to view an example with a BMV-712 battery monitor and simple Multiplus control options. After following the link, open the Vanlife Outfitters 12V Internal BMS (Advanced) Wiring Diagram to view an example with a Lynx Shunt and Cerbo GX communication center. If you have AC loads that should ONLY be powered by shore (utility) power, (not inverted AC power), you can use the “AC out 2” connections on the MultiPlus inverter/charger which is only “live” when shore power is available. One good example of this would be an AC/DC refrigerator. Many of those will “default” to AC power when it’s available. If you wired up an outlet near your refrigerator that was powered by the inverter, the fridge would switch to that source of power anytime the inverter was on (inverting) which is less energy efficient that it continuing to run off the 12 volt DC power. If, instead you wire up that AC outlet that feeds the refrigerator, it will only run off the AC power when you have shore/utility power. If You’re Using a Renogy DC-DC Charger Instead of the Victron Orion Units Unlike some other battery-to-battery charging products that sense voltage and trigger the charging based on that, the Renogy DC to DC charger (or battery-to-battery charger) that I used requires you to connect up a 12 volt positive “signal wire” from the vehicle’s ignition switch so that it only charges from the van (vehicle) battery when the ignition is turned on. Without this ignition trigger on this unit or the voltage sensing on others, the battery-to-battery charger could easily drain the van battery since the battery-to-battery charger would be pulling current without the alternator providing a charge. After some research I discovered that some Promaster vans (2016 or newer I think) have a “Upfitter Connector” on the passenger side “pillar” which is that area just behind the passenger seat where the seat belt connects to the van wall. If you remove the black plastic trim at the bottom of this “pillar” you’ll see a white multi-pin connector (photo below). This is the “upfitter connection” that provides a variety of connection points for the Promaster in one spot. This PDF file (Promaster Upfitter Connector Diagram PDF) details this connector including what each pin on the connector is/does. Turns out that pin #13 is an “ignition feed” that has 12 volt positive when the ignition switch is on. So, I used this to be the “trigger” for the Renogy DC to DC charger. Note: if you have an older ProMaster that does not have this upfitter connection you can consider splicing into the cab area cigarette lighter wiring as detailed in this post. Another option is to use a “tap a fuse” type splitter on fuse #31 in the Promaster fuse block (below the steering wheel). The photo shows this location. These things allow you to maintain the fusing for the original circuit but tap into that fuse location for a second circuit. In this case you’d use a 5 amp fuse for each. Close Up Shot of Promaster Van Upfitter Connector with Pin #13 Connected: In order to do this, I had to order the correct, “male” version of this connector (part number 1-480710-0) as well as the “pin” itself (part number 350218-1). The way this works is that you solder the correct wire to an empty pin and then insert that pin into the correct position on the connector thus allowing you to access and wire up a variety of things to this upfitter connector. These parts are pretty inexpensive so I bought a few with the expectation that I’d destroy a few figuring out how this all works. I’m glad I did because I did indeed destroy a few experimenting. Ultimately, it’s not difficult but finding the right parts and how they fit together took some time. So hopefully this saves you that time! Soldering the Wire to the Pin: The wire coming out of pin #13 on the Upfitter Connector runs back to the rear passenger side wheel well where the primary electrical system is installed and is connected to the Renogy DC to DC charger on a terminal labeled “D+”. Below is a photo of this connection: Next I had to configure the Renogy DC to DC charger to correctly charge the lithium batteries using the DIP switches pictured above. The manual for this Renogy DC to DC charger is really bad and the section on setting up the DIP switches is complete gibberish. I gave up on it pretty quickly and called into Renogy support. The correct DIP switch settings for charging lithium batteries with the Renogy DC to DC charger is: Switch #1: Off Switch #2: On Switch #3: On Switch #4: On Switch #5: Off Turning On The LED Lights On The Lynx Distributor There are LED lights on the Lynx Distributor that indicate if each of the circuits is live (the fuse isn’t blown). They light up green when it’s good and red when it’s not. These lights are normally powered when the Lynx Distributor is paired up with the Victron Lynx Shunt but you don’t need that if you use the “better-for-vanlife” (my opinion) BMV-712 battery monitor (listed above) which has it’s own shunt for monitoring. So, if you don’t want to buy that hardware but do want the fancy lights, you can “hack” the lights with a 12 volt DC to 5 volt DC converter and an RJ11 “phone style” connector. This will provide the 5 volt power the LED lights need to fire up. Below is an illustration on how you’d do this – at your own risk, of course.
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