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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. 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 24V Internal BMS Wiring Diagram for our example wiring corresponding with this blog post. 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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The Best Van Features from 2025 Tampa RV Show
In this video we take a field trip to the 2025 Tampa RV show where Zach checks out the coolest, newest and most innovative van features!
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Installing a Nations Secondary Alternator into a Promaster Camper Van
In this video we’ll show you an overview of the process for installing a Nations high output secondary alternator and Wakespeed WS500 regulator in a Ram Promaster (Similar process for Mercedes Sprinter and Ford Transit). This van was built out a few years prior but the owner wanted to be able to recharge his batteries quicker than standard combination of vehicle alternator charging with a DC-DC charger and solar. Because his van used Battleborn batteries, which are approved by Wakespeed the upgrade was fairly simply from an electrical point of view. Battleborn is one of the very few internal BMS (“legacy”) batteries that are officially supported by the Wakespeed regulator. Learn more about the Wakespeed and why some battery brands are approved in our deep dive with the creator of the Wakespeed. You’ll see how the secondary alternator addition becomes the most powerful of 4x charging sources in this van (solar, shore power, vehicle alternator, secondary alternator) making it a worthwhile upgrade for those that like to be off grid while staying comfortable! This is especially true for vanlifers who are looking to install a 12v, 24v or 48v air conditioner in the camper van. You might also be interested in our complete secondary alternator power system bundle with Victron batteries and components.
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All About Fiamma Awnings
In this video we’ll talk about all the options and models when it comes to Fiamma awnings. There are a lot of different models and options for the various van chassis and sometimes it can get a little overwhelming. We’ll attempt to clear up any confusion about models, features, functionality, etc while also discussing some of the pros and cons about the awnings themselves.
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Thinsulate vs. Wool Insulation for Camper Vans - We Tested Both!
In this video we enlisted a third-party testing lab to find out…once and for all…which is better…3M Thinsulate or Wool. Van insulation is a pretty hot topic and everyone seems to have an opinion on what is best to insulate their camper van. Well, we wanted to eliminate any bias or opinion and take a more scientific approach. We had the lab test things like weight, thickness, sound absorption, R-Value, hydrophobicity, odor, and more to finally determine which product is the best for insulating your camper van. This video has a lot of great information about things like sound and moisture absorption, but to be honest, it can be a little dry (pun intended). To make it up to you, scroll down a little further to see our Mad Van Laboratory version. No facts but pretty entertaining. At least we had fun making it! While you’re here, consider reading our other post how to insulate your camper van with Thinsulate. The Mad Van Laboratory Version (!)
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Van Tour - Tons of Clever Features - LuberCraft
Take a tour of this recently completed van by our neighbor, LuberCraft Custom Vans & Skoolie’s in Sarasota, Florida. LuberCraft is one of the premier van builders and installers in the Southeastern United States. They are known for high quality, detailed finishes and technologically advanced systems… not to mention excellent customer service! Products From Our Store Used In This Build Lonseal Lonstrand Topseal flooring Mabru RV12000 12v air conditioner Dometic NRX 80 refrigerator Victron, 12-volt secondary alternator electrical system bundle Webasto Air Top 2000 STC diesel heater Isotemp Spa 20 water heater
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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 many items ship free. We 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
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VANLIFE PRODUCT REVIEW: Isotemp Water Heater
Virtually FREE and LIMITLESS hot water? …YES PLEASE!!! In today’s Vanlife Outfitters Video, we are reviewing the Isotemp line of water heaters that use your engine’s coolant to heat your water as you drive. It’s a great feeling to not have to dip into your battery bank to produce hot water, but these versatile water heaters also have an electrical element for rare situations where you might not be driving or idling your van. We’ll talk about it’s pros and cons, go over it’s specs and talk about why someone would want to use it in their van. We’ll also compare it to other popular water heaters on the market. Isotemp Water Heaters Isotemp Install Kit Isotemp Blog Post
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