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Kick The Tires And Light The Fires: Turning On Your Camper Van Electrical System For The First Time!
Amps vs Amp-hours. Current vs capacity. A classic rivalry! No. Wait. How can we pit these two important parameters against each other when they’re complementary? This blog revisits some important subtopics on sizing your electrical system, with a focus on how much current (Amperes, or Amps) and storage capacity (Amp-hours, or Ah) your system may need. Why is there a 250 Amp fuse on my 300 Ah battery? You’re selling a 460 Ah battery, so do I need more than one battery in my system? What’s with all the 4/0 cables, can’t I use smaller ones? These are some common questions we receive about our example wiring diagrams. Let’s try to clarify current and storage capacity using a few examples with our old friend the free example load calculation Google Sheet. Current Current is the measure of the flow of electricity through a conductor. At a high level, current flowing from your batteries provides the power (which is current times the battery voltage) needed by your loads to operate. There are a few important considerations in determining your system’s current needs (or is that need for current? bad pun). First, what is the maximum current needed by your loads at any given time? This number is likely much higher than the average load consumption that you analyzed. Looking at Example 1 in the load calculation sheet, let’s consider that you come back to your van at the end of the day after a nice, long hike. You turn on the air conditioner (at max for a while to cool things down), turn on some lights, notice that your refrigerator is running to keep things cold, and fill a pot with water to start boiling on the induction cooktop. Did you look at your battery monitor and realize that you’re using around 250 Amps of current (roughly 3000 Watts on your 12 Volt system) for a little while? Perhaps you made a cup of coffee or threw something in the microwave too, and you peaked at nearly 400 Amps of current! This usage is actually typical, and we should plan for it. Because our vans are our homes, no one wants the power to go out while enjoying our vans. Second, the maximum load current above leads to another consideration of your system’s need for current: the battery specifications. As an example looking at our SOK 314 Ah batteries, the manufacturer recommends a continuous current of 150 Amps charging and 200 Amps discharging. Exceeding these continuous values can degrade your batteries’ long term performance. Given the significant investment in your batteries, this is one of the reasons we suggest multiple batteries in parallel when designing a system. Each additional battery reduces the discharging demand from the other batteries, maximizing short-term and long-term battery performance. Stated differently, batteries in parallel increases the current capability of your system. In this example with SOK 314 Ah batteries, two batteries safely supports 400 Amps continuous discharging as compared to 200 Amps from a single battery. As a result of considering current, we typically recommend three (but at least two) batteries in the scenario above. Capacity Capacity is a little more straightforward to consider, and capacity is well-covered in our sizing your electrical system blog. Capacity is how long can your system sustain your current consumption (Amps multiplied by time) and that’s typically best to consider using the average consumption calculations laid out in our free example load calculation Google Sheet. Capacity is additive, so each battery adds to the total available capacity in your system. Again returning to Example 1, now let’s consider that you plan to boondock for four nights. No shore power. No driving. While solar is great when you have it, you decide how certain you are to predict sunny skies during the day, and that assumes that you don’t park in the shade anyways. (Spoiler alert, on my trips it rains anyhow!) If you maintain the average consumption of around 250 Ah a day for four nights, you’ll want more than four times that capacity in your battery bank. Don’t forget another important battery specification, the manufacturer’s recommended depth of discharge, which is typically 80% to maintain good performance over the life of your battery. In our capacity example, we would recommend at least four SOK 314 Ah batteries (or at least three Epoch 460 Ah batteries) to meet your boondocking goals. Wrap-up Also necessary in your considerations is design margin, or some additional comfort zone if your usage predictions are off. Maybe you use the van differently than you projected, or what if you decide to add another gadget to better enjoy your van? You don’t want to plan your system right at the edge of manufacturer specifications. On top of that, there’s Physics to deal with…current increases as battery voltage decreases (which is during discharging), some loads have inrush or starting currents even higher than typical consumption, and efficiency decreases with increased heat. Design margin, as well manufacturer recommendations, are additional reasons that multiple, paralleled batteries are best suited for most van applications to address both current and capacity. Let’s wrap up by revisiting the three common questions above with our Amps vs Amp-hours knowledge. Why is there a 250 Amp fuse on my 300 Ah battery? We’re back to Amps vs Amp-hours confusion, aren’t we? Your maximum load calculations, spread across multiple parallel batteries, help determine the expected maximum current from each battery. Fuses are specified to protect the cables, and the cables are specified for the maximum expected current plus margin. It’s perfectly normal for a 300 Ah battery (for example, with specifications for 200 A continuous and 400 A peak current discharging) to be fused at 250 A. You’re selling a 460 Ah battery, so do I need more than one battery in my system? Maybe you’re building out a minimalist van, and your load calculations suggest some combination of low current or low duration meets your needs. Or maybe you’re always plugged in to shore power. In those cases, yes one battery may be perfect. For many of our customers, off-grid capabilities combined with daily van needs like cooking or cooling will lead to different conclusions. That’s why our example diagrams and recommendations typically reflect systems with 2-4 batteries in parallel. What’s with all the 4/0 cables, can’t I use smaller ones? This topic is related to current and fuse selection, but it comes up often enough to touch on in this blog. As you can see on this handy wire gauge calculator, maximum current is only one of the factors in properly designing your cables. You can use smaller diameter cables, if your fusing and current consumption is reduced, among other things. One way to reduce large diameter cables is using multiple batteries in parallel such that each battery contributes less current (through appropriately reduced fuse sizes). Another way to reduce cabling size is to increase system voltage (to 48 Volt or 24 Volt). Quadrupling the voltage reduces current by a factor of four, and the lower current reduces cable losses…because Physics. Reducing current allows significantly smaller cables to be specified (again, with appropriately reduced fuse sizes). Current? Or capacity? With modern advances in battery technology, vanlifers are the winners on both counts!
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How To Choose Solar Panels For Your Camper Van
This blog details the steps we suggest to pick solar panels for your rig. First step, play Tetris! How much space do you have available for solar panels on your roof? Start by determining if you will be mounting your solar panels to a roof rack, OEM roof rails with crossbars, or some other method. Mounting solar panels using Z brackets to crossbars is our go-to approach. Take away space for your vent fan(s), rooftop air conditioner, Starlink mount, recovery boards, rooftop deck, or other rooftop accessories. That remaining space (hopefully there is some left over!) can get filled with solar panels. Just like all of the tradeoffs inside your rig, you have to make tough decisions on what can fit on top too. Here’s the part that’s not as much fun as it sounds: play panel Tetris, looking at the dimensions of the solar panels while trying to maximize the usable space. Different vendors may have different dimensions for the same panel wattage. Roughly speaking, you will find that panels with lower wattage ratings are correspondingly smaller. Remember that you’re trying to maximize the rooftop area covered with panels, so selecting a smaller panel may allow you to fit more total wattage on your roof. Also keep in mind that mixing different panel sizes is not recommended, so you’re trying to maximize the number of identical panels to fill up your rooftop space. We find that solar arrays like this Newpowa 220 Watt panel with the long side dimensions of <57″ fit well to maximize the horizontal rooftop space on a van. Because of all those other must-have items, many customers may settle for a 400ish Watt array using two panels mounted horizontally. The good news is that the above steps are where all the tough decisions have to happen. The rest is “easy”. Let’s talk about panel voltage Solar panels are marketed in 12 V and 24 V options. One manufacturer’s 12 V nameplate does not mean that another manufacturer’s 12 V specifications are identical, and in fact those specs can vary greatly. 48 V options in solar panel sizes fitting vehicles are not readily available at this time. You picked a 12 V battery bank, you picked a 12 V inverter/charger, so naturally you pick a…well sorry to confuse you, but with solar panels the nameplate voltage doesn’t really matter. What does matter are a few details: The specifications of the solar panel, particularly the Voc, or the open-circuit voltage which is the maximum voltage that the panel will produce How the panel(s) are wired, in series or parallel. Wiring panels in series increases voltage, and wiring panels in parallel increases current. Hopefully a quick set of examples will clarify this confusion. Take a look at the Newpowa 200 Watt 12 V panel specs, and compare those specs to the Newpowa 200W 24 V panel. The 12 V panel has a Voc rating of 24.34 Volts, while the 24 V panel has a Voc rating of 48.68 Volts. You may be thinking those voltages are so high, how can either of these panels work with my 12 Volt electrical system!? The key is that the MPPT charge controller converts the PV (photovoltaic, i.e. solar) side voltage to your BATT (battery) side voltage. In fact, you want the PV side to be a high voltage to allow smaller cables, minimize voltage drop, and minimize losses. Can I use 24 V solar panels in a 12 V system? Yes. Using a 24 V panel like the Newpowa 200 W 24 V panel in a 12 V system allows you to either use panels in series for more efficiency or use panels in parallel for better partial shading performance (or both! two series panels with two more series panels in parallel). In a small solar array, even using only one 24 Volt panel can still work well for a 12 V system. Can I use 12 V solar panels in a 24 V system? Yes, with a caveat or two. In order for the MPPT charge controller to start a charging cycle (in other words, for the MPPT to become a useful device by turning on and supplying power to charge your batteries) the PV voltage must be higher than the BATT voltage. In Victron MPPT charge controllers, this voltage difference must be more than 5 Volts. Using two or more Newpowa 200 W 12 V panels in series meets that requirement in a 24 Volt system, as the PV voltage becomes much higher than the nominal battery voltage. Can I use 12 V or 24 V solar panels in a 48 V system? Yes, with the same caveats as above. Especially with 48 V systems that are typically paired with a secondary alternator kit to rapidly recharge while using a rooftop air conditioner, there may not be tons of space on the roof for solar. That’s just one of the tradeoffs when selecting a 48 V system. Solar arrays with three or more 12 V panels in series or two or more 24 V panels in series are typically required in 48 V systems. Picking a MPPT charge controller Victron MPPT charge controllers have two numbers on each device (for example, 100/50), and here’s the breakdown on those numbers: The first number is the maximum voltage that the controller can tolerate. Do not exceed the nameplate voltage rating or device damage may occur. Also note that the Voc rating discussed above is a nominal value, and the actual maximum voltage varies with temperature. Each solar panel manufacturer provides an additional rating for temperature coefficient for Voc (or another similar name & specification). The second number is the maximum current that the controller can source to your batteries. If you have more solar power available than the maximum current rating, no damage occurs but you don’t get to use all of the available power. Because our solar panels are seldom oriented perfectly at the sun, and you only get so many days of ideal solar panel per year, a slightly undersized MPPT charge controller may not be noticeable to your charging performance. These two MPPT numbers sound a little complicated, so use a cheat sheet. And by cheat sheet, we mean this great MPPT calculator from Victron. Here’s the best way to use the MPPT calculator: 1) Start typing your solar panel vendor and SKU in the Solar Panel field. If you’re in luck, your solar panel model is already in the list. If not, try 1a. 1a) Okay, your model didn’t show up. No problem! Find the Advanced Panel Settings slider and enable advanced mode. 1b) Act advanced. Seven panel specifications become available for editing, and for most manufacturers you need to copy & paste those seven specifications from their panel datasheet to the calculator. Pretty advanced, huh!? 2) Set your system Voltage to 12/24/48. This setting is your battery voltage, because we already told you panel voltage is pretty meh 3) Adjust the Series and Strings parameters to yield the number of panels you can fit. Series is obvious, increase this number if you need/want panels in series. Strings means parallel, increase this number for more Y-branch connectors and panels in parallel. It’s okay to play around with these settings too, adjust series or parallel values and see what the calculator tells you. Some panel configurations offer you a tradeoff, while others just require you to wire your solar array a specific way to make it work. 4) Bonus choice: set your location to see an estimate of how much daily yield your solar panel may provide. But you’re in a van and traveling the world, so maybe you care more if it’s going to rain tomorrow than what your yield would be if you parked in Albuquerque for a month? Now look on the right side of the calculator for the Result. Victron tells you the best MPPT charge controller for your array, and they show you lots of fun details why it’s the best controller too. Yay! For some customers, especially those on larger rigs like trailers, going with two MPPT charge controllers with two types of panels may be a useful choice to maximize area. Using two MPPT charge controllers is also a good choice for “ground deployed” solar panels that get temporarily set up in conjunction with fixed rooftop panels. And, you get to play Tetris and use the calculator twice. Fun times. Wrap up Maybe you’re the TL;DR type, but we hope you read through the details above. To wrap it up, we suggest the following steps to pick your solar panels: 1) Play Tetris with your panels to fit as many identical panels as possible on your roof 2) Use the MPPT calculator to select your charge controller That’s not hard! But if you run into any snags, our tech support team is always ready to help you understand more about our solar products and blogs. Contact us!
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Watt Hours Vs Amp Hours
Watt-Hours vs. Amp-Hours: What Every Van Builder Needs to Know If you’re building your own van’s electrical system, you’ve probably seen batteries advertised in amp-hours (Ah), while solar panels and appliances often list power in watts or watt-hours (Wh). Here’s the problem: mixing these up can lead to a seriously undersized system — and that’s how you end up with a dead fridge, no lights, and warm beer halfway through your road trip. By the end of this post, you’ll know exactly what these terms mean, how they’re connected, and how to use them to plan your off-grid electrical setup with confidence. Amp-Hours: The Current Over Time An amp-hour (Ah) is a measure of how much current a battery can deliver over time. Think of amps like the width of a water hose — the bigger the hose, the more water (current) can flow. Amp-hours tell you how much total flow you get over a certain period. Example: A 100Ah battery could, in theory, supply: 1 amp for 100 hours 5 amps for 20 hours 10 amps for 10 hours Key point: Amp-hours alone don’t tell the full story — you also need the voltage. Watt-Hours: The Real Energy Number A watt-hour (Wh) measures total energy — this is the true “fuel tank size” for your battery. Here’s the connection: Watts = Volts × Amps Watt-hours = Volts × Amp-hours So if you know a battery’s amp-hours and voltage, you can find watt-hours. Example: 100Ah at 12 volts = 1,200Wh 100Ah at 24 volts = 2,400Wh Why it matters: Two batteries can have the same amp-hour rating but store very different amounts of energy if their voltages are different. That’s why watt-hours are better for comparing systems. Example of our Victron LFP-12.8/300 packs nominal energy at 3840Wh Lithium Batteries can be found here: https://www.vanlifeoutfitters.com/category/camper-van-electrical-system-parts/batteries/ The industry is headed towards rating battery power by the nominal energy voltages. Instead of seeing 12, 24 or 48 volts the industry uses 12.8, 25.6 and 51.2 volts as the nominal values for watt hour calculations. Why Watt-Hours Matter More for Off-Grid Systems Amp-hours are useful when you’re staying in one voltage (most van systems are 12V), but watt-hours let you: Compare batteries of different voltages (12V, 24V, 48V). Calculate your daily power needs accurately. Match your battery capacity to your solar panel output and appliance usage. If you only look at amp-hours, you might undersize your system and run out of battery faster than you expect. How to Calculate Your Daily Power Needs Before buying batteries, figure out how much energy you use in a typical day. Here’s how: Step 1: List your appliances. Write down every device you’ll use: fridge, lights, fan, water pump, laptop, etc. Step 2: Find the wattage. Look for a sticker on the device, the manual, or search online. If it only lists amps, use: Watts = Volts × Amps Step 3: Multiply by hours used per day. This gives you watt-hours for that device. Step 4: Add everything up. That’s your daily total watt-hours. Example Daily Usage Table: Appliance Watts Hours/Day Daily Wh 12V fridge 50 8 400 LED lights 20 4 80 Vent fan 30 5 150 Air Conditioner 600 5 3000 Phone charging 10 2 20 Total — — 3650Wh Step 5: Add a safety margin. Cloudy days, inverter inefficiencies, and battery aging happen. Add 20–30% to be safe: 3650Wh × 1.25 ≈ 4,562.5 Wh/day needed. Converting Between Ah and Wh If you already know one measurement, here’s the cheat sheet: Ah = Wh ÷ Volts Wh = Ah × Volts Example: You need 4,562.5Wh per day. With a 12V system: Ah = 4,562.5 ÷ 12 ≈ 381Ah So you’d want at least a 460Ah lithium battery bank (lithium batteries can use most of their capacity, however manufactures only recommend 80% depth of discharge or less; lead-acid can only use about 50%). With your daily Wh usage calculated, remember you must have a charging source that is capable of replenishing the used energy each day too. This can be from solar, dcdc chargers, 2nd alternator, shore power or generator. Common Mistakes to Avoid Comparing Ah without checking voltage. A 100Ah 12V battery is not the same as a 100Ah 24V battery. Forgetting inverter losses. Converting 12V DC to 120V AC loses ~10–15% of energy. Only planning for sunny days. Always size for your worst-case scenario. Not tracking usage. A battery monitor like a Victron SmartShunt helps you see real-world consumption. Final Tips for DIY Van Builders Always start with watt-hours when planning your system. Use efficient appliances — LED lights, efficient DC fridges, and laptops instead of power-hungry desktops. If you can, test your system before hitting the road. Remember: you can always add more solar panels later, but battery capacity is harder to upgrade in a cramped van. Conclusion: Understanding watt-hours vs. amp-hours is one of the most important steps in building a reliable off-grid van electrical system. Once you get the hang of converting between them, you can size your battery bank, solar array, and charging system with confidence — and keep your lights on and fridge cold, no matter where the road takes you. If you need assistance putting together your electrical system, please call 754-444-8704 an agent at Vanlife Outfitters will provide their expertise in the perfect electrical system for your application.
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24V Camper Van Secondary Alternator Electrical System - More Options at 24 Volts!
Example 24V Camper Van Electrical System with Victron NG Batteries and Secondary Alternator Jump To Example Wiring Diagram Product Bundle For This System COMING SOON Options. Voltage. Capacity. Charging methods. Brand. Topology. Are there too many options for your camper van electrical system? If your answer is Yes, then we’re here and happy to help. Reach out to us, and our goal is to help you understand more about our camper van electrical system bundles (or any product in our store!). We pride ourselves on actually responding to your emails or picking up your phone call. We may even be working from our vans while we’re doing it! Whether your answer above was Yes or No, this blog post is a reminder that you do have options. In particular, we’ve added to our suite of free example wiring diagrams to include a complete 24 Volt electrical system based on Victron NG batteries that can be paired with a high-power secondary alternator for charging. 12 Volt, 24 Volt, or 48 Volt? Shore power, DC-DC (primary alternator), secondary alternator, and/or solar charging? Yep, you can do that. Let’s talk about this 24 Volt Victron NG-based electrical system Options does not have to mean Complication. In fact, this 24 Volt NG electrical system for your camper van has CAN ( “controller area network“) communication so that you don’t need to fiddle with every device configuration to get the system working well – all of the major system components “talk” to each other and communicate with the batteries for safe, reliable and fast charging or discharging. In Victron-speak, these devices are Smart. This bundle can include a ~3,600 Watt (150 Amp) Nations secondary alternator plus an additional 700 W (or more) of DC-DC charging from the primary alternator. That’s a lot of charging power while driving. Sure, adding a little bit of solar charging can help keep up with those house loads too. As far as discharging, a Multiplus “3000” is still probably in the sweet spot, capable of surging up to 5500 Watts of AC load. What’s different with this system? Not a lot really. In the example wiring diagram, you’ll see many similarities to our 12 Volt and 48 Volt secondary alternator system bundles. Of course we’ve carefully selected 24 Volt equipment in this case. And there’s still some 12 Volts running around as discussed in this blog. If you’re considering a 24 Volt system, we expect that you’re selecting as many 24 Volt appliances as possible, but it’s hard to completely remove 12 Volts. Air conditioner, refrigerator, air heater, lighting, pumps,… the list goes on, and yep, you can do that at 24 Volts. The number of 24 Volt loads may turn out to be one of the more annoying issues to handle in this system. And it’s not that bad. You can easily expand the 24 Volt distribution with a second Lynx Distributor, but the distributor uses MEGA fuses that only go down to 40 Amps. The example wiring diagram shows a Littelfuse MIDI Fuse Holder that can provide an extra 2 or 3 loads with MIDI fuses that go down to 30 Amps. Rather than inline fuses for the multitude of smaller load branches at 24 Volts, it may make sense to use a DC fuse block wired from the Lynx Distributor. Many sizes of DC fuse blocks are offered by Blue Sea, including this one with six circuits. The primary non-Smart device shown in this system is the venerable Orion 24/12-70 DC-DC converter to supply that aforementioned 12 Volts. It’s possible to use the newer Smart Orion XS 1400 as the 24/12 converter instead. Using the XS 1400 gives you more visibility into your 12 V load consumption, and it provides the voltage conversion at a higher efficiency (maximum of 98.5% efficient versus 92%). Efficiency is the name of the game for a 24 Volt system, so for some customers the XS 1400 as the 24/12 converter can make sense. In the example wiring diagram, you’ll also find a small reminder that the Lynx Smart BMS NG provides an Allow To Discharge (ATD) signal. ATD can be used to stop devices from discharging the batteries, extending the “smart” operation of your system and protecting your batteries. We show a simple wiring example where the Orion 24/12-70 DC-DC converter is enabled/disabled by ATD, and that technique can be expanded using a Smart BatteryProtect. Here’s a hypothetical use for a Smart BatteryProtect: maybe you don’t want your high-power 24 Volt air conditioner to run your batteries flat overnight while you’re boondocking. Waking up with no power available is so much fun! How many times have I said System in this blog? Not enough, apparently. The key part of safe, reliable and fast charging is that your electrical components have been carefully selected and proven to be interoperable. Particularly in the case of the Nations secondary alternator with Wakespeed WS500 Pro regulator as a charging option, your electrical system should include batteries officially supported by Wakespeed to work correctly and safely. The Victron NG BMS & batteries, Wakespeed regulator, and Cerbo running DVCC (along with all those other Smart devices) perform as a system that has been tested, can be supported, and is proven to operate to meet your camper van’s demands. Wiring diagram and bundle Click here for the 24 Volt electrical system with secondary alternator kit free example wiring diagram. This system can be purchased through our build your own bundle page. You’ll get our best bundle pricing and fast & free shipping, and of course you’ll get the electrical system best tailored to the needs of your van. If you have questions about this 24 Volt camper van electrical system, reach out to us and someone from our tech support team will be happy to assist you. Download Wiring Diagram PDF – 24V Electrical System Victron NG Batteries and Secondary Alternator Summary: 24V Camper Van Electrical System with Secondary Alternator Kit at a Glance A 24 Volt camper van electrical system with a secondary alternator is one of the most reliable ways to power high-demand, off-grid living. By reducing current and wire size, 24 Volt systems improve efficiency and make it easier to run heavy loads like air conditioning and refrigerators. Many DIY camper van builders still rely on 12 Volts for lights, fans, and pumps, but adding a 24 Volt alternator setup gives you faster charging and greater flexibility. If you’re planning a complete camper van electrical system, consider whether 24 Volt is the right balance of simplicity, performance, and long-term reliability. FAQ: 24V Camper Van Electrical Systems Is 24V better than 12V for a camper van electrical system? A 24 Volt camper van electrical system is more efficient for high-power setups. Because the voltage is higher, the current is lower — which means smaller wires, less energy loss, and better efficiency. A 12 Volt system is often enough for simple camper van electrical systems, but if you want to run appliances like air conditioning or refrigerators off-grid, 24 Volts is usually the smarter choice. Do I need a secondary alternator for my camper van electrical system? Not every van needs one. A secondary alternator kit is ideal if you drive or idle often and want reliable, high-output charging for a large battery bank. For smaller or simpler camper van electrical systems, a DC-DC charger connected to your stock alternator may be enough. In fact, both a secondary alternator and a DC-DC charger can be combined for massive charging power! Can I mix 12V and 24V in the same camper van electrical system? Yes — many builders do. A common setup is to use 24 Volts for high-draw loads (like heavy appliances such as air conditioners and refrigerators) and keep a small 12 Volt distribution panel for lights, fans, and pumps. This adds a little bit of complexity, but it’s a practical solution when you want the efficiency of 24 Volt and the necessity of 12 Volts. How much does a complete camper van electrical system cost? Costs vary depending on power needs. A simple setup might run $1,500–$3,000. A complete camper van electrical system with a large lithium battery bank, secondary alternator kit, and a 3,000W inverter/charger can cost $10k+.
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Current vs. Capacity: Understanding Amps and Amp-Hours in Your Van Electrical System
Amps vs Amp-hours. Current vs capacity. A classic rivalry! No. Wait. How can we pit these two important parameters against each other when they’re complementary? This blog revisits some important subtopics on sizing your electrical system, with a focus on how much current (Amperes, or Amps) and storage capacity (Amp-hours, or Ah) your system may need. Why is there a 250 Amp fuse on my 300 Ah battery? You’re selling a 460 Ah battery, so do I need more than one battery in my system? What’s with all the 4/0 cables, can’t I use smaller ones? These are some common questions we receive about our example wiring diagrams. Let’s try to clarify current and storage capacity using a few examples with our old friend the free example load calculation Google Sheet. Current Current is the measure of the flow of electricity through a conductor. At a high level, current flowing from your batteries provides the power (which is current times the battery voltage) needed by your loads to operate. There are a few important considerations in determining your system’s current needs (or is that need for current? bad pun). First, what is the maximum current needed by your loads at any given time? This number is likely much higher than the average load consumption that you analyzed. Looking at Example 1 in the load calculation sheet, let’s consider that you come back to your van at the end of the day after a nice, long hike. You turn on the air conditioner (at max for a while to cool things down), turn on some lights, notice that your refrigerator is running to keep things cold, and fill a pot with water to start boiling on the induction cooktop. Did you look at your battery monitor and realize that you’re using around 250 Amps of current (roughly 3000 Watts on your 12 Volt system) for a little while? Perhaps you made a cup of coffee or threw something in the microwave too, and you peaked at nearly 400 Amps of current! This usage is actually typical, and we should plan for it. Because our vans are our homes, no one wants the power to go out while enjoying our vans. Second, the maximum load current above leads to another consideration of your system’s need for current: the battery specifications. As an example looking at our SOK 314 Ah batteries, the manufacturer recommends a continuous current of 150 Amps charging and 200 Amps discharging. Exceeding these continuous values can degrade your batteries’ long term performance. Given the significant investment in your batteries, this is one of the reasons we suggest multiple batteries in parallel when designing a system. Each additional battery reduces the discharging demand from the other batteries, maximizing short-term and long-term battery performance. Stated differently, batteries in parallel increases the current capability of your system. In this example with SOK 314 Ah batteries, two batteries safely supports 400 Amps continuous discharging as compared to 200 Amps from a single battery. As a result of considering current, we typically recommend three (but at least two) batteries in the scenario above. Capacity Capacity is a little more straightforward to consider, and capacity is well-covered in our sizing your electrical system blog. Capacity is how long can your system sustain your current consumption (Amps multiplied by time) and that’s typically best to consider using the average consumption calculations laid out in our free example load calculation Google Sheet. Capacity is additive, so each battery adds to the total available capacity in your system. Again returning to Example 1, now let’s consider that you plan to boondock for four nights. No shore power. No driving. While solar is great when you have it, you decide how certain you are to predict sunny skies during the day, and that assumes that you don’t park in the shade anyways. (Spoiler alert, on my trips it rains anyhow!) If you maintain the average consumption of around 250 Ah a day for four nights, you’ll want more than four times that capacity in your battery bank. Don’t forget another important battery specification, the manufacturer’s recommended depth of discharge, which is typically 80% to maintain good performance over the life of your battery. In our capacity example, we would recommend at least four SOK 314 Ah batteries (or at least three Epoch 460 Ah batteries) to meet your boondocking goals. Wrap-up Also necessary in your considerations is design margin, or some additional comfort zone if your usage predictions are off. Maybe you use the van differently than you projected, or what if you decide to add another gadget to better enjoy your van? You don’t want to plan your system right at the edge of manufacturer specifications. On top of that, there’s Physics to deal with…current increases as battery voltage decreases (which is during discharging), some loads have inrush or starting currents even higher than typical consumption, and efficiency decreases with increased heat. Design margin, as well manufacturer recommendations, are additional reasons that multiple, paralleled batteries are best suited for most van applications to address both current and capacity. Let’s wrap up by revisiting the three common questions above with our Amps vs Amp-hours knowledge. Why is there a 250 Amp fuse on my 300 Ah battery? We’re back to Amps vs Amp-hours confusion, aren’t we? Your maximum load calculations, spread across multiple parallel batteries, help determine the expected maximum current from each battery. Fuses are specified to protect the cables, and the cables are specified for the maximum expected current plus margin. It’s perfectly normal for a 300 Ah battery (for example, with specifications for 200 A continuous and 400 A peak current discharging) to be fused at 250 A. You’re selling a 460 Ah battery, so do I need more than one battery in my system? Maybe you’re building out a minimalist van, and your load calculations suggest some combination of low current or low duration meets your needs. Or maybe you’re always plugged in to shore power. In those cases, yes one battery may be perfect. For many of our customers, off-grid capabilities combined with daily van needs like cooking or cooling will lead to different conclusions. That’s why our example diagrams and recommendations typically reflect systems with 2-4 batteries in parallel. What’s with all the 4/0 cables, can’t I use smaller ones? This topic is related to current and fuse selection, but it comes up often enough to touch on in this blog. As you can see on this handy wire gauge calculator, maximum current is only one of the factors in properly designing your cables. You can use smaller diameter cables, if your fusing and current consumption is reduced, among other things. One way to reduce large diameter cables is using multiple batteries in parallel such that each battery contributes less current (through appropriately reduced fuse sizes). Another way to reduce cabling size is to increase system voltage (to 48 Volt or 24 Volt). Quadrupling the voltage reduces current by a factor of four, and the lower current reduces cable losses…because Physics. Reducing current allows significantly smaller cables to be specified (again, with appropriately reduced fuse sizes). Current? Or capacity? With modern advances in battery technology, vanlifers are the winners on both counts!
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DIY Camper Van 24V Electrical System
Example DIY Camper Van 24V Electrical System (Internal BMS batteries) Jump To Example Wiring Diagram Product Bundle For This System In this post we’re going to discuss a popular topic these days – 24 Volt electrical systems. This system offers some benefits compared to the traditional 12 Volt electrical system detailed in our original camper van blog post. This post includes a detailed wiring diagram and system bundle 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…including more efficient use of those power-hungry rooftop air conditioners. What’s different? Well the battery bank is 24 Volts instead of 12 Volts, obviously. Except the system has 12 Volts too. Let’s un-confuse things. Looking at the 24 Volt example wiring diagram as compared to the 12 Volt example wiring diagram, all of the key features and components are quite similar between the two systems. There’s still a Victron Multiplus inverter/charger, one or more DC-DC (alternator-based) chargers, solar capability, an optional Victron Cerbo communication center, the ability to use shore power, and a load center for AC & DC. Victron, other battery manufacturers, air conditioner companies, and large segments of the camper van and marine industries have long supported 24 Volt equipment. While the 24 V system looks quite familiar, each equipment model has been carefully selected for compatibility with a 24 Volt house (domestic) battery system. So why is there still 12 Volts then? Because some popular equipment in our vans still only operates on 12 Volts. We’re looking at you MaxxFan (at the moment, anyways). But we’ll explain shortly why this additional wrinkle is not hard to overcome, and more importantly why considering a 24 Volt system may be a better choice for some vanlifers. Also different in this 24 Volt system is a new product from Victron, the Orion XS 1400 DC-DC charger. The XS 1400 operates in 12 or 24 Volt systems, can charge up to 50 Amps, and supports parallel operation like existing Orion XS chargers. Why is 24 Volts better? Efficiency is the name of the game for a 24 Volt system. Higher voltage systems are well suited for large DC loads like rooftop air conditioners. On our website we’ve already shown how much more efficient DC air conditioners can be over traditional AC air conditions. But take a closer look at the specifications on some of our air conditioners or the comparison spreadsheet. In particular, let’s look at air conditioner capacity in BTUs versus power consumption. The Nomadic Cooling X3 offers a great example, where the 24 V X3 and 12 V X3 have the same rated power consumption, yet the 24 V model has a rated cooling capacity that is 12% higher! Why? Because the air conditioner operates more efficiently at the higher operating voltage. Other air conditioner brands and models show similar efficiency benefits. Since an air conditioner may be the single largest, sustained load for an off-grid camper van, improvements in efficiency are a big deal for maximizing your battery capacity. While some van products don’t run on 24 Volts yet, and we’ll get back to those, you will find that a majority of your DC system can operate natively at 24 Volts. Of course this includes your Victron components like the Cerbo and chargers, but you can also find refrigerators, water pumps, LED lighting, fans, and host of other equipment working at 24 Volts. While we’re harping on efficiency, let’s not miss out on a chance to consider a little Physics. By increasing the house voltage to 24 Volts over 12 Volts, the required current is reduced by 1/2. Resistive losses in your cabling (commonly referred to as I2R losses), have been reduced significantly (almost by 1/4, due to the I2 factor). Note that we say almost 1/4, because with the reduced current you’re likely to use smaller cable gauges for lower cost and easier wiring. Smaller cable gauges do have higher resistance per foot, however not by a factor of 2 given the range of cables we’re using. So reduce by 4, increase by less than 2, blah blah blah…using 24 Volts gives you less losses (greater efficiency) and smaller cables. That’s a win. Better equipment performance and less cable losses with smaller/cheaper cables, those are the main reasons why a 24 Volt system may be the right choice to maximize your battery capacity and improve your off-grid experience. Things to consider: So why are we not talking about a 48 Volt system here? Good question. And maybe we will be. 48 Volt air conditioner performance and efficiency is a great reason to consider a 48 Volt system over 12 Volts (and 24 Volts). However, many of the other camper van items (like refrigerators, possibly the second highest power consumer in most systems) are not readily available at 48 Volts. For now, we’ve found that 24 Volts offers a significant improvement with a majority of the system running at the house voltage, avoiding having to turn around and run most of the equipment at 12 Volts anyways. Included in this system is a Victron Orion 24/12 Volt converter. With as many loads as possible running natively on 24 Volts, the 70 Amp 24/12 converter is more than sufficient for most customer’s needs. You need to be mindful that there is now a 24 Volt distribution center (using one or more Lynx distributors as shown in the example wiring diagram) as well as a 12 Volt distribution center (shown using our favorite WFCO combined AC/DC load center). For this system, we think that the improvements in performance offset the small increase in components required to use both 24 Volt and 12 Volt equipment simultaneously. Solar charging is readily supported on a 24 Volt system, and most Victron MPPT chargers automatically select the house voltage. Because the MPPT chargers require a PV voltage higher than the house battery voltage to initiate a charge cycle, solar selection is a tiny bit (and we really do think it’s tiny) harder to select. Most customers can use two or more solar panels (typically in series), and there are 24 Volt solar panel options out there, like this one from Newpowa, where customers using only a single panel or desiring a parallel panel configuration can still effectively utilize solar. 48 Volt solar charging is a little more limited in this case, primarily because rooftop DC air conditioners necessarily compete with space for enough panels. There are not a lot of options for 48 Volt panels that fit on camper van rooftops, so multiple 24 Volt panels in series are typically needed. While solar charging for a 48 Volt house system is possible, it’s another minor reason why a 24 Volt system may be a good compromise right now. Wiring Diagram Our example wiring diagram shows Epoch 24V 230Ah V2 Elite Series batteries. These are excellent value batteries supporting communications to a Victron GX Device (such as a Cerbo GX) for advanced monitoring and charging using DVCC (cables included). The Elite Series batteries include internal heaters. A system with just two of these batteries provides 12,000 Watt-hours of power capacity, which is a great starting point for your off-grid adventures. While we think the Epoch batteries are a great choice, this system bundle could operate with any 24 Volt Bring-Your-Own internal BMS battery from SOK or other reputable manufacturers. Download Wiring Diagram PDF – 24V Electrical System (Internal BMS Batteries) Tips If you Bring-Your-Own-Battery, programming your system at 24 Volts will be similar to the steps we’ve shown with our 12 Volt internal BMS system. Programming examples include the Multiplus and Cerbo GX configuration, where you’d carefully replace 12 Volt specifications with appropriate parameters from your 24 Volt battery manufacturer. If you select the Epoch Elite batteries as part of bundle, the batteries include a cable for connecting the batteries to a Cerbo GX. Most customers will want to take advantage of these features, using the following steps as part of the installation: Set the battery DIP switches per the manual, representing the battery configuration and total capacity of the battery bank in your system. Install the communications cables per the battery manual, specifically making sure that the INV-labeled end of the Victron cable is connected to the Cerbo GX. Daisy chaining of multiple Epoch batteries is done with the CAN-labeled cable. Terminators are not required. Taking note of which VE.CAN port on the Cerbo you’re connected to, ensure that the CAN profile is correctly set: Console(Remote Console) > Settings > Services > VE.Can port # > CAN-bus profile > (select the CAN-bus BMS LV (500kbit/s) setting) Assign the Cerbo to use the Epoch BMS as the battery monitor (see note below): Settings > System Setup > Battery Monitor > select (Epoch BMS name) on CAN-bus. Alternatively, if you installed a Victron shunt, you would select that shunt as the battery monitor. Configure DVCC. When using the DVCC, you need to assign Epoch as the controlling BMS on the Cerbo: Settings > DVCC > Controlling BMS > select (Epoch BMS name). NOTE: The Epoch batteries will aggregate multiple batteries into one battery BMS/shunt to be displayed & utilized by the Cerbo GX. An additional system shunt is not required, but through testing, we have discovered that the internal BMS will not register current below 1 Amp. There will be a SOC drift of unregistered current resulting in an actual SOC that is lower than the reported SOC. The solution is to install a Victron shunt and to use that as the battery monitor yet still use the Epoch BMS as the controlling BMS in the DVCC settings. Epoch is aware of this issue and have stated that they are working on the issue.
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Overview and Demonstration of Victron Energy DVCC
DVCC (Distributed Voltage and Current Control) is an awesome feature of Victron Energy power systems that intelligently coordinates charging your battery bank with multiple charging sources if you have Victron chargers and a GX device such as a Cerbo GX. This video dives into what it is and how it works! Shopping for a power system and want the best technical support in the industry? We’re a stocking distributor that ships fast and free and have your back when you have questions! Resources mentioned in the video: 1) Using a SmartShunt as a “DC Meter” 2) Wakespeed WS500 Alternator Regulator DVCC Information 3) Requirements for using DVCC 4) DVCC compatible batteries tested by Victron Energy
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Deep Dive - Wakespeed WS500 Wiring Harness Video
If you’re confused about all the connections on the Wakespeed WS500 alternator regulator wiring harness this video will detail each leg and connection for you. Want to nerd out some more about the Wakespeed? Check out this other deep dive with one of the creators. You might be interested in our best price secondary alternator electrical system kits that include everything you need at an awesome price with our world-class support. Check out the blog posts below that also link to an example wiring diagram and the product bundles! 12-Volt Secondary Alternator Camper Van Electrical System Kit 48-Volt Secondary Alternator Camper Van Electrical System Kit
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Overview of the Cerbo GX / Ekrano Products from Victron Energy
Update December 2024 For a period in 2024 Victron was offering three versions of the Cerbo GX as we detailed in this video (Cerbo GX, Cerbo-S GX and the MK2 model). Now, starting in early 2025, they are eliminating the Cerbo GX and the Cerbo-S GX so that there will, once again, be only one single model which is the MK2 version. In other words. the Cerbo GX MK2 replaces the original Cerbo GX and the Cerbo-S GX is no longer available. Victron also offers an “all-in-one” model called the Ekrano with integrated screen but, since all the connections are on the back of the screen, it only makes sense if this screen is located near your power system which is often under the bed/garage area of a camper van. We also recommend reading our blog post about configuring a Cerbo GX device in a mobile power system like a camper van or RV.
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