DIY Camper Van Electrical System Design
* * Disclaimer: We are not professional electricians. This system is what worked in our van. Use at your own risk and always do your own research.
When we were building out our camper van we went back and forth on how we were going to power everything within the van. Electrical systems can be complicated and trying to make sure our camper van could function off grid for extended periods of time was a big factor in our final design. We didn't want to find ourselves always looking for a campground that had shore power connection or have anxiety about our refrigerator running out of battery power.
We were really pleased with our electrical system. It never ran out of power on us and performed well on a day to day basis. So let's dive into the steps that we took to design, assemble, and use our camper van electrical system.
Calculating Power Needs for Your Camper Van Conversion
So how do you know how much power you'll need for your camper van conversion? The beginning of the camper van electrical system design process is figuring out how much power you expect to use on a daily basis in the van. This will help you decide what size battery you need for your camper van. Every device you use, whether it's a refrigerator or a fan, requires a certain amount of energy to operate. The best way we've found to evaluate electrical needs is to create a spreadsheet that calculates the amount of power used by each device per day. The main purpose of the calculator is to make sure that you are not consuming more power than you are generating on a daily basis. Assuming you want your van electrical system to be off grid capable that is. If you're planning on staying in campgrounds with power hookups most of the time, you just want to make sure that your battery storage is large enough to last between hookups.
** If you want a step by step guide on how to create this spreadsheet or to buy a pre-made one check out our blog post that explains our electrical system calculator to give you a jump start.
If you prefer using your calculator for all the math, we'll guide you through the steps to determine the power consumption of a device in relation to the capacity of a battery bank. Power in watts can be calculated by multiplying the voltage that a device operates at by the current flow that a device pulls in amps. So if you have a 12 volt fan that runs at 2 amps it will consume 24 watts of power while running. A battery bank is usually sized in Ah, or amp hours, so we'll have to do some more math to figure out how long we could run the 12 volt fan off of a certain battery. Amp hours means that the battery can discharge current of 100 amps for one hour before running out of power. If the battery bank is 12 volts then we can use the formula from above to calculate 12 volts multiplied by 100 amps is 1200 watts. We now know that the battery can supply 1200 watts for one hour. If the fan only consumes 24 watts then you divide 1200 watts by 24 watts to solve for the number of hours that the fan could run before the battery bank runs out of electricity.
** If the calculations in the last paragraph brought back memories of stressful math tests, simply download our electrical system calculator, and it will handle everything for you.
Van Electrical System Batteries
There are a lot of different battery options out there when it comes to storing power for your camper van electrical system. The choice can be an overwhelming one so we're going to break down the different types and the pros and cons of each battery option. We personally went with lithium batteries and used a recycled Tesla battery module but this is just one option out of many. The three main classifications of batteries for a van electrical system are: lead acid batteries, agm batteries, and lithium batteries. Let's look at how to differentiate the different battery types.
Like we discussed above, a battery's capacity is rated in amp hours. This is the amount of current or amperage that can be discharged for one hour before the battery dies. Another factor to consider is the weight and size of the battery. Let's face it, van life is cramped as it is so you generally don't want massive heavy batteries taking up all of your living space. The voltage of a battery is another thing to consider. Due to Ohm's law, the higher voltage that a battery is, the lower amount of current that has to be pulled in order to get the same power output. Typically batteries come in 6 volt, 12 volt, 24 volt, or 48 volt. It's up to you to decide what works best with the wire gauge you want to use and the rest of the components in your van electrical system. Different batteries perform better or worse in certain temperatures as well. Some lithium batteries even require active heating and cooling in order to stay in an optimum operating range.
Each battery type has its strong suit whether it's cost, battery life, or usable capacity.
Lead Acid Batteries
Lead Acid batteries are the most cost effective option when it comes to batteries for your van electrical system. You can find them at most auto parts stores, and almost all battery charger options have a charge profile to keep them maintained properly. While these batteries are cheap and simple to wire up, they can be lacking when it comes to battery capacity. The usable capacity of a lead acid battery is roughly half of the rated capacity. So if you purchase a 100 amp hour lead acid battery you can really only use 50 amp hours of it before the battery dies. Another downside to lead acid batteries is their weight. They are the heaviest option for batteries on our list. In cold weather, their performance also suffers greatly as they rapidly lose voltage under load.
AGM Batteries
AGM batteries are the middle ground of the battery options. They have better battery capacity than lead acid batteries but not quite as much as most lithium batteries. They perform slightly better in cold weather, but still take a hit if you're using your van in really cold climates. When it comes to weight and size, they are evenly matched with lead acid batteries. However, AGM batteries do have more capacity than lead acid because the depth of discharge is lower. Overall, we didn't think it was worth paying more for AGM batteries compared to lead acid ones since the benefits aren't that much better, except for a bit more depth of discharge.
Lithium Batteries
When it comes to performance, lead acid and AGM batteries don't compare to lithium batteries. Lithium batteries have a much higher upfront cost, but in our opinion are the best choice for a van electrical system. A lithium battery has a much deeper depth of discharge than other battery choices. Therefore, you can take lithium batteries down to 85%-90% of the rated storage capacity and recharge them without damaging the battery. When it comes to weight and size, lithium batteries are much lighter and smaller than their counterparts and still store more power. The only downside besides cost on lithium batteries is that they must be in a certain temperature range to charge. It's important to ensure that your charge controller has a temperature monitor that will not charge the battery if the battery temperature is below it's rated threshold. Some newer lithium batteries are being sold with a heating element made into them to prevent this issue.
Tesla Battery Module Feedback
After doing all the battery research, we chose to use a recycled Tesla battery module for our house battery for a few main reasons. The first being that the Tesla module was the cheapest lithium battery on the market at the time we were building our van in 2020. Another advantage was its 24-volt configuration, allowing us to use smaller gauge wire for wire sizing. The last big advantage was the size and shape of the Tesla module. It snugly fit mounted on the rear wall of the camper van, occupying minimal space.
Now you're probably thinking why doesn't everyone go this route if a Tesla battery module is so great? Let's dive into some of the downsides of using a Tesla battery module. First of all if you want a simple camper van electrical system with an easy to follow wiring diagram, then you want to steer clear of a Tesla module. The primary purpose of a Tesla battery is to power a car, not your LED lights and rooftop fan in a camper van electrical system. With that being said, we had to do extensive research to set up our electrical system to function with the Tesla battery. We utilized high-quality components from Victron, which provided us with the flexibility to program them to operate within the specifications of the Tesla battery module. It wasn't just a matter of connecting the components and hitting the road in the van. We needed a specific battery monitor capable of balancing the cells of the batteries, as it lacked an internal BMS like most off-the-shelf solutions have. Another specific item we had to use because of the Tesla battery module was a heating blanket with a thermostat that was installed on the battery. This made it where the battery temperature was regulated and we could charge the battery in any environment.
Figuring out all the nuances of the Tesla module was fun, and we never ran out of power in our van when we used it. We even ran our air conditioner off of it from time to time. If you're interested in going the Tesla route, you can purchase our wiring diagram that shows all of the components you'll need to get up and running with a Tesla module. It's definitely not the cheapest path to take on a van conversion, but we knew the cost would be worth it.
Power Generating Devices for Your Van's Electrical System
We've covered how to do the bare minimum calculations to size the batteries in your van and talked about different types of batteries, so now it's time to dive into all the devices that can generate power for your van build. There are four main sources of power when it comes to van camper van electrical systems: solar power, shore power, alternator charging and running a generator. You certainly don't need to have all of them in your van electrical system, but you have to have at least one or your batteries will never charge.
It's important to note that a battery monitor is a valuable part of your van electrical system as well because it will show you whether you are using more power than you are bringing in, or vise versa. Usually they have a physical display that shows your current battery voltage, your load on the battery system and the amount of power being collected from the different devices discussed in this section. Investing in a battery monitor with advanced features allows for the breakdown of ac and dc loads, with multiple display pages providing detailed insights into the health of your van's electrical system. The battery monitor is typically the "brain" of your camper van electrical system. It collects information from all the devices within the electrical system and shows it in an easy to read display.
Solar Power
Solar power is probably the most common power source when it comes to camper van electrical systems. A basic solar system consists of a solar panel, a solar charge controller, wiring, and batteries. The solar panels harvest power from the sun and the wiring carries the power to the solar charge controller. The solar charge controller acts like a battery charger and converts the power from the solar panels to the right voltage and amperage to charge the batteries correctly. If you want to do a more complex solar system, you can use multiple solar panels like we did. You can also use multiple solar charge controllers and batteries. Just keep in mind that the more components you use, the more complex your wiring diagram and installation will be. There are many solar panel manufacturers out there that offer solar panels of different sizes and voltages. The main thing to keep in mind is the output voltage and amperage of your panels must match the input voltage and amperage of your solar charge controller.
Solar Panels
Most van electrical systems have more than one solar panel in order to harvest enough solar power to keep the battery bank fully charged. On our camper van we used six 100 watt Renogy panels all wired to a single solar charge controller. To minimize wire gauge, we connected two sets of three panels in series, then wired these two groups of panels together in parallel. This increased the voltage and kept the amperage lower. It also allowed us to position the individual panels around the air conditioner and rooftop fan opening on our roof.
Solar Charge Controllers
There are two options when it comes to solar charge controllers. MPPT and PWM represent the two types, and we'll highlight several key distinctions between them. MPPT is a newer technology, and they are typically more expensive than a PWM charge controller. The main difference is that the MPPT controller can adapt better in partially sunny environments and give a more consistent power output than a PWM controller. MPPT controllers can also step down the voltage and amperage. However, a PWM controller must be sized for the exact input of the solar panels and the exact output needed to charge your battery bank. The cost difference is not very extreme, and we chose to use a MPPT controller on our camper van electrical system. Some MPPT charge controllers are programmable and can be optimized for the type of batteries that you are using for your house battery.
Shore Power, Generators, and Inverter Chargers
If you're looking for a cost effective and easy way to keep your batteries charged, then shore power is probably the route you want to take. A shore power connection receives alternating current, or AC power, and converts it into direct current, or DC power, using an inverter. It then uses a dc charger to recharge the van battery. Many camper vans don't have ac power wired throughout the van, but they do have a single shore power plug that goes to a dc charger like we talked about above. Shore power connections are popular because most campgrounds have them, and a 30 amp 120 volt connection means you charge your batteries at 3600 watts. This amount of power is higher than any solar system mounted to your van or a dc charger running off of your camper van's alternator will generate .
Shore power connection would also be where you would hook up a generator to power your van. Most gasoline or diesel generators create ac power, meaning they would hook into the same port that you would use to connect shore power to at a campground. During our travels we never carried a generator, but it would have been a great way to add capacity to our off grid set up. Generators are also convenient when you are running air conditioners for long periods of time. They can be a valuable back up to your van electrical system.
Inverter chargers are an important part of almost every van electrical system. They act as a battery charger and an ac inverter. Inverter chargers can also function as a transfer switch to control whether devices are getting ac power from your battery or a shore power connection. Your battery monitor usually integrates with the inverter charger to show what power source is running the components in your camper van electrical system. We used a Victron inverter charger in our camper van and were very pleased with it. We were able to configure it for the exact charging characteristics that matched up with our Tesla battery module. This made it where we could safely charge our Tesla battery from shore power and run all of our 120 volt appliances and outlets from it as well.
If you are not planning on using an inverter charger in your camper van electrical system, then you'll have to have a regular battery charger that can convert your shore power connection to a dc charger. A stand alone battery charger is almost always cheaper than an inverter charger because it is a simpler approach. Sometimes a simple van electrical system is better, and a stand alone battery charger will connect to shore power and charge your battery just fine.
Alternator Charging or dc to dc Charging
Every camper van electrical system could benefit from tapping into a power source that is already on your van. Your van engine has an alternator to keep the engine battery fully charged while you are driving. Vans vary in alternator sizes, so it's essential to research the voltage and amperage output of your engine alternator capabilities before deciding to connect it to charge your house battery. Our van was pre-wired for a second battery so all we had to do was extend the existing wiring from under the passenger seat back to our Tesla battery that was located at the rear of the van. That wiring hooked up to a Victron dc to dc charger that had the correct charge profile to work with our Tesla battery module. However, you don't have to have a Tesla battery in order to have a dc to dc charger. They are compatible with almost any battery type. With this electrical system in place, our camper van house battery was being charged any time we had the van running. Another important thing to note is that you need to have a low voltage disconnect that will switch the dc to dc charger off when the van alternator is not providing power. Some dc to dc charger systems have this switch integrated into them. For example, the Victron dc to dc charger we chose did have the low voltage switch integrated in so we never had to worry about our house battery draining the van starting battery.
Powering the Different Devices In Your Camper Van
We've covered how to store power and generate power, so now it's time to get into how we use the collected and stored power to run all the appliances in your camper van. This section below is where we'll talk about wiring diagrams, bus bars, wire, an ac distribution panel, a fuse, and much more. Once you've decided how you're going to collect and store your power, the next step is to create a wiring diagram that shows how all of the components are wired together or connected wirelessly.
Creating a Wiring Diagram
If you've never created a wiring diagram it can seem overwhelming, but there's really not much to the process. At times, it's more effective to develop several smaller wiring diagrams and then integrate them as you progress. If you opt for this method, start by drafting a wiring diagram solely for the solar system. Next, develop a separate diagram specifically for your shore power system. Proceed systematically, tackling each system individually until you have thoroughly mapped out each one. What you'll notice is that they all tie back to your main house battery. If you're ready to dive in and create a single wiring diagram encompassing all components of your entire van electrical system, we'll guide you through it step by step, helping you to tackle it with confidence.
** Note: it's always good to use pencil when following these steps :)
Take a sheet of paper and put a small square in the middle and label it battery. Put another square above it and label it battery monitor.
On the right and left side of the battery make a square. Label the right one negative bus bar and the left one positive bus bar. These bus bars are where all of your connections to the battery will land.
Between the positive bus bar and the battery, make another square and label it fuse. Fuses are important because they protect the battery from either discharging or charging with too much current.
Above the battery make a square for each device that will generate power or charge the battery. This includes solar power, shore power, generators, and alternator charging.
Below the battery on the left side make a square for each device that you want to power that uses dc power.
Below the battery on the right side make a square for each device that you want to power that uses ac power.
Between the dc powered devices and the positive bus bar place another square for a fuse block. Each device you hook up to dc power should have its own fuse that is rated for that device. Now you can tie all of your dc components together with a line to show the wire diagram.
Between the ac powered devices and the positive bus bar you'll need to add a square for a power inverter. A power inverter turns dc power into ac power, or vice versa. Some inverters are also a battery charger and a transfer switch. If this is the case for you then you can go ahead and connect your shore power square to the inverter square via a line that stands for wires.
Between the inverter and your ac devices you need to place an ac distribution panel. This is similar to a breaker box in your house and acts just like the fuse block on the dc side. Now tie all of your ac components to the ac distribution panel with a line.
Now it's time to place a circuit breaker between the positive bus bar and each power source that you've chosen to use and then connect them with lines.
Now connect all of your devices back to your negative bus bar and your diagram is ready for the next step.
Van Electrical System- Wiring Components Together
Now that you've got your electrical road map laid out, it's time to get into the details of wiring and how to connect all of the devices on your wiring diagram together. The most important thing to note when wiring a van is that camper vans are a vehicle and not a house. There are two main types of electrical wire: solid core and stranded core. Solid core wiring is used in houses that do not bounce down a road with electricity running through them. Vehicles use stranded wire due to the fact that there is motion involved, and stranded wire is much better at conducting electricity while being moved around. If you use solid core wiring in a moving vehicle you run the risk of the wiring heating up and melting through the insulating jacket. This could cause a fire.
Wire Length, Wire Gauge, and Wire Type
The next thing to consider is the size or wire gauge that you are going to use. This depends on the voltage and amount of current or amperage that flows through the wire. Wire length and the amount of time that the electricity will be flowing through it are also important factors. With all of these variables, it's much easier to check out our youtube video on how to size the wire in your van electrical system. The video breaks down a simple way to correctly size all of the wire lengths in your camper van electrical system. Another crucial point to consider is that your solar panels require a specific type of wire with jacket rated for UV exposure. Solar panels mount on the roof of your van and are exposed to sunlight that can degrade regular wiring.
Wiring Connections On Your Wiring Diagram
Now that you know what type and gauge wire to use in your camper van electrical system, it's time to talk about the actual connections themselves. When it comes to vehicle wiring there are a few preferred methods to connecting wires. For all of your bus bars, connecting the wires is fairly straightforward. Crimp properly sized ring terminals onto the ends of the wire and use heat shrink tubing to cover up the crimped area. It's important to take care making sure no exposed strands of wire stick out past the heat shrink tubing. Also make sure not to stack more than three ring terminals on top of each other on a single stud of your bus bars. If you run out of connections purchase another bus bar and wire it in appropriately.
When it comes to connecting two wires end to end, heat shrink butt splices are our preferred method over soldering. The reasoning is that soldering tends to weaken the joint due to the application of heat to the wires during the soldering process. When the wires are crimped together with a butt splice and then sealed inside a waterproof heat shrink, the joint can withstand movement better. Many wiring diagrams won't go into this much detail when it comes to connecting the individual wires together, but we felt it was important to mention.
Camper Van Electrical System Wrap Up
We hope this blog gives you the information and understanding to create your camper van electrical system on your own. We honestly enjoyed every part of the van conversion process and used our knowledge from working on electrical systems in marine applications to design our wiring diagram for our camper van. If we were to do it all over again and do another van conversion, we don't think that we would use a Tesla module as the heart of the van electrical system. While it did store a lot of energy for the cost and made it where we could run large ac loads, it made our wiring diagram overly complicated. It also forced us to use ultra premium components in order to configure them properly to protect the Tesla module. Our ac to dc charge controller, alternator charging, solar charge controller, and fuse selection was more difficult due to the use of the Tesla module. Other lithium batteries have come a long way since we did our van conversion, and we would probably use an off the shelf option now if we were to do another van conversion.
If you have any questions or want some more information on our design shoot us an email. We're always happy to help out in any way we can to get your van life journey started!
Check out our video below for a closer look at how to design your camper van's electrical system using a Tesla battery module.
