Complete DIY Guide to Your Van Electrical System • Engineers who Van Life (2024)

DIY-ing a conversion van electrical system is one of the most daunting parts of your camper van build.But, it is also one of the most essential. Because, without power, well, you can’t do much, van lifer, or not! So, after DIY-ing two of our own camper vans, andhelping countless others via 1:1 Consulting, we are here today to help you understand and master your camper van electrical system.

We will first talk about all of the components you will need and their proper sizes, how to connect them by selecting the proper wire gauges, and then finally how to protect the components with fuses, conduit, and more. Let’s get to it.

The basis of every camper van electrical system is going to be very similar; batteries, how you charge them, and how you discharge them. It is really important to grasp these basics before you dig into the nitty gritty of wire gauge, amps, volts, watts, etc. Don’t worry, we’ll get there eventually! The basic flow is shown below and we will delve into it in depth throughout the next sections.

Camper van batteries can be charged 3 different ways:

1. Solar Power
2. DC-DC Charging while you drive
3. Shore Power

Camper van batteries can then be discharged in 2 ways:

• DC power usage
• AC power usage (outlets)

This is visualized in the diagram below.

In the diagram above, you can see the three main ways to charge your camper van house batteries. We always recommend having at least 2 of these options as a van lifer for redundancy and rainy days (literally):

1. Using solar power!You can install a Solar Charge Controller to convert free energy from the sun into usable energy in your camper van. This is a fantastic way to charge; however, it can rarely be relied on fully do to solar angles changing as you drive around the country, seasons changing, and cloudy days.
2. Using a DC-DC Charger! You can install a DC-DC charger between your chassis battery and your house battery. This component then pushes charge via your alternator to your house batteries as you drive while keeping everything safe and cool.
3. Using shore power! You can install an Inverter Charger and then plug your camper van into shore power to charge from a plug.

With DC power, the current stays constant in one direction and the voltage remains consistent. What really matters here though is that DC power is anything that is hardwired into your system. Most camper van electrical systems are 12V, or 24V. DC power is the most efficient power as it does not need to be converted prior to use, therefore, you should utilize this wherever possible! Examples of DC loads include:

• USB plugs
• Puck lights
• Water pumps
• Toilet fans
• Fridges

With AC power, the current changes direction occasionally and the voltage follows a sine wave like pattern. These characteristics make it ideal for larger load applications. The best way to think of AC power, is an outlet. Anything that plugs in to an outlet is pulling AC power! Therefore, in your camper van, some examples of AC loads are:

• Blenders
• Induction Stove Tops
• Espresso Machines 😉
• Power tools

Now that you understand the basic flow of a camper van electrical system, here is an example of one in practice! We drew up a diagram of our second conversion van’s electrical system for free download below.

We know how batteries are charged, and how they are discharged. Let’s now discuss the components you need to actually DIY your van electrical system. For each component we will discuss what it is used for and how it works:

1. Batteries
2. Inverters and Inverter Chargers
3. Solar Panels
4. MPPT Solar Charge Controller
5. DC-DC Chargers
6. Lynx Distributors and Bus Bars
7. Ve.Bus
8. Smart Shunt
9. DC Fuse Panel
10. AC Distribution Panel
11. Master On/Off Switch

There are two main types of batteries in camper van systems: Lithium Iron and AGM. The decision is often brought down to a combination of budget, weight, and battery life.AGM batteries are cheaper, heavier, and can only be discharged to half capacity before sustaining damage. Lithium Iron batteries are more expensive, lighter, and can be discharged nearly fully.

Let’s work through an example. Say you need 200ah of battery capacity (audit coming later…), you would only need 200ah of Lithium batteries; however, if you choose AGM, you need 400ah of batteries to achieve the 200ah of usable capacity.

Related Reading: Campervan Lighting Options Compared

Your AC power audit calculations require one more step as about 15% of usable power is lost in the conversion from DC -> AC power. Therefore, you will need to divide each calculation by 0.85. This is factored into the calculator, but if you aren’t using it, here is your warning! Below is our sample AC power usage audit:

Our total estimated power consumption from this audit is238.8Ah. So, wecomfortably went with 400ah in our first build and upgraded to 540ah in our second van build as the more capacity = more days self sustainable.

In practiceour average daily discharge is 180Ah.

Inverters convert the 12/24V power in your batteries to usable 120V power. Another way to think about this simply is that inverters are what deliver power to your outlets that your AC appliances need. During this conversion, about 15% of usable power is lost, making it a bit less efficient than direct DC power.

Now that you know if you want an inverter, or an inverter charger for your camper van, let’s figure out how to size it properly. To size your inverter, you will need to determine the maximum current you will be drawing from your camper van electrical system at any one time. Luckily, you already did this above in the AC power audit. Determine which AC loads you will be running at the same time, any given time. Then, get an inverter that is rated slightly higher than that sum.

For example, our power highest draw would be about 1900W if we were cooking on theinduction stove topand running theblenderat the same time.We ended up with a3000W Inverter chargerbecause 1900 was just a little too close to 2000W and we simply didn’t want to worry.

Afull power auditwill guide you to how muchsolaryou will need to provide ample electricity for youvan batteries. But! We can tell you that maximizing physical solar panel SIZEsaves a ton of work during your install!

For solar systems greater than 300 W, drop those100 W panelsand instead opt for175 W,200 W, or even larger residential solar panels. Onour van, Rover, we have 2x 370 W residential solar panels. Using larger solar panels simplifies the wiring and mounting of your panels and likely allows you to fit even more solar on your van roof! Additionally, if you can source “residential panels” they are a tad more efficient. However, sourcing a small quantity of large panels may be difficult, so just do what you can.

The tradeoff with maximizing solar is you lose deck space! Soplan your roof layout wisely.

AMPPT Solar Charge Controller (Maximum Power Point Tracking Solar Charge Controller) is the component of your electrical system that converts the voltage of the solar energy you harvest and delivers it to your batteries at the optimal voltage that is safe for them to charge at. A solar charge controller is needed if you want to use solar panels.

MPPT Charge Controllersare more efficient than other charge controllers on the market because they can deliver a higher percentage of power to the batteries. They do this by simultaneously increasing amperage while decreasing voltage of the current.

Your solar charge controller should also have a thermal circuit breaker so that you can shut off solar panel charging if needed.

Solar Charge Controllers will have numbers after them, for example “100/30”. These numbers represent the maximum voltage and maximum current they are rated for. For example, a Victron MPPT Solar Controller (100/30) will have a maximum voltage of 100V or 30A of current. The number you are aiming for is unique to your specific solar setup. To determine what is safe for your system you need to know how many solar panels you will have and how you are going to wire them.

If your panels are wired in parallel,take the amperage of each solar panel and add them.

If your panels are wired in series,take the voltage of each panel and add them.

The resulting number should not exceed the rated voltage and max rated amperage of the charge controller.

Here’s a working example. We have 400W of solar panels wired in parallel. Each panel (100W) is about ~5A. This results in ~20 total amperage. We chose a 100/30 Charge controller since neither our voltage nor current will exceed 100V or 30A.

The purpose of a DC/DC charger is to charge your batteries while you drive. This is done by a DC/DC charger sitting between your house and chassis batteries. The DC/DC charger is safer than a standard battery isolation manager (Li-BIM) as it is able to control the current and voltage going in to your precious house batteries. However, they each do the trick and we have used them both.

Charging via DC-DC chargers are a great addition to any van electrical system, especially to help you get through the winter!

Typically in a van electrical system there will be quite a few cables coming off your battery terminals, and they stack up quick. For this reason, you will need a bus bar to extend the positive and negative terminals in a clean manner. Additionally, you could choose to install a Lynx Distributor that is essentially a positive and negative bus bar in one. Lynx Distributors are a modular bus bar that has space for equipment circuits and fuses.

Bus bars, and Lynx Distributors, prevent us from unruly stacking on the battery lugs. This creates a cleaner system, and allows us to monitor the paths separately.

We do not recommend running your inverter all of the time since it really is not an efficient use of energy. This presents a difficulty as most van builds have the inverter in the “garage” area so turning it on and off is a challenge. However, a ve.bus dongleis a Victron component that enables Bluetooth for your inverter. Itconnects to your inverter with a simple ethernet cable (or Victron has one for ease) and allows you to toggle the on/off switch and change Inverter settings from the Victron Connect app.

** This only works with Victron Inverters.

Monitoring your batteries is crucial, especially for the first few weeks of van life as you figure out how much power you actually use. Ashunt measures the voltage and current, in and out of your battery. This allows it to accurately measure battery status. A smart shuntuses bluetooth to use your phone to display status. Alternatively, you can use a battery monitor such as the BMV 712 with a physical display.

To sum it up, all battery monitors require a shunt in front of the batteries to measure status, but from there you can choose what your display device is: a physical display, or straight to your phone. We prefer the SmartShunt connection to our phones as we can access status from anywhere near the van.

** Your shunt must be sized to accommodate the total amps of your system.

ADC Fuse Panelserves as the distribution point for all of your DC appliances (determined in your Audit!). Think:roof fans,lights, fridge, heater,USB plugs, etc. All of these “points of use” are hardwired into your DC Fuse Panel with a properly sized fused. We discuss fuses in the “Protect Your Camper Van Electrical System section”

Similar to the function of your DC fuse panel, each outlet in your van should be on its own circuit breaker and to accomplish this you will need an AC Distribution Panel. Power goes from your inverter into your AC Distribution Panel, through individual circuit breakers, and finally exits the panel to your AC outlets. Standard household outlets are on 15amp circuit breakers and work well for most AC needs. Heavier duty outlets are rated to 20amps and work be better suited for applications such power tools, induction cooktops, water heaters, and other high wattage devices.

We briefly mentioned above that most van electrical systems are 12V. However, there is also a place for 24V systems in some situations.Voltage is defined as the potential difference, or in practical terms the “speed” that electrons will travel through an electrical circuit.Most generally, the larger the battery capacity system, the higher the battery voltage is appropriate.

We recommend 12V batteries for under 7kWh (~580 amps). 12V batteries are generally easier to source and have more manufacturer options. In addition, they do not need modifications for DC appliances as most usually run 12V.

We recommend 24V batteries for larger systems over 7kWh. These batteries will be more expensive and more complicated to wire. However, they are more compact and energy dense! You will need a 24V-12V converter for all 12V devices.

There are only two pieces of information you need to select proper wire gauge: the current of the load, and the distance that load has to travel from power source to appliance (ie wire length). You can always use a larger gauge wire, but the reverse is not true and can result in catastrophic failure of your system. The downside to larger gauge wire is that it is harder to work with and more expensive.

In residential wiring, solid copper wire is the “norm” but when building a van stranded copper wire is needed as it is much more resistant to the daily vibrations your van is subjected to. Can you use solid copper wire? Sure. Do we recommend it? No.

As power travels from the power source to the load, it encounters a small amount of resistance in the wire which causes the voltage to drop. Therefore the voltage at your endpoint is never the full voltage leaving your voltage source. Certain appliances can tolerate more or less voltage drop than others: we call these critical drop and non critical drop appliances. Critical drop appliances can only tolerate a 3% voltage drop and non critical voltage drop can handle up to a 10% voltage drop.

Critical voltage drop wires include those connecting the batteries, the inverter, MPPT charge controllers, and your DC fuse panel – basically the bones of your electrical system. Non critical voltage drop wires are those going to your individual point-of-use appliances that are generally more tolerant to fluctuations in voltage (disclaimer: please check with your appliance manufacturer to be sure).

Once you have the above information for each load, use the below chart to determine what gauge wire you need. You can begin to increase sizes of wires such that you don’t have to buy different wire for all appliances. Again, be sure to not undersize wires! For example, in our van build we narrowed down to12 and 16 gauge wirefor our DC appliances.

Source: Blue Sea Systems

It goes without saying that all electrical systems need protected, not just campervan electrical systems. One of the dangers of a van’s electrical system is rubbing through the insulation on a wire, and then creating contact between said copper wire and van. This would ground the system to your chassis unexpectedly, and can even result in vehicle fires.

In camper vans, especially, you have to route your wires through small spaces, they come into contact with sharp edges, and on top of that, your vehicle is constantly moving and shaking.For all of these reasons, we tend to overprotect our system with all three of the following:

1. Fuses
2. Sheath
3. Conduit

All systems should include fuses. From there, wire sheath and conduit and recommended but not required.

A fuse is a thin strip of metal that melts when there is an overcurrent. This melting opens the circuit thus cutting power supply to the device on the other end. Fuses are an essential part of any campervan electrical system and probably the most known way to protect an electrical system.

To choose the proper fuse, start by checking the device on the circuit. That is the best recommendation to follow! If that is not present, use the following:

• Maximum Fuse Size: Use the chart below
• Minimum Fuse Size = Appliance Amperage x 1.25

We personally recommend blade style fuses with the Blue Seas System DC Fuse Block. It’s simple, and CLEAN.

Wire sheath is an expandable braided sleeve that adds a layer of resistance to rubbing and cutting, or “abrasion resistant”. We cover our wires with wire sheath when they pass through the wall cavities. We noticed a lot of sharp edges in the cavities, so this gave us more confidence in our system. We used:

• Alex Tech Wire Sheath (varying sizes)

Wire conduit is a plastic-y covering that you slide over the wires. We added this as a final layer of protection if the wire sheath was rubbed through.

• 5/8in Wire Conduit(fits multiple small wires that run together)
• 3/8 inch Wire Conduit (fits one larger wire)

1. Arrange and mount all electrical components in a tidy and logical position. Be sure to account for the ability to run wires to them.
2. Wire your batteries together. We have a cost effective DIY Battery Cables guide for this.
3. Deliver power to your bus bars, switch, shunt, on/off switch and main battery fuse.
4. Then, wire all of your bus bar connections first. This includes your MPPT Solar Controller, DC to DC Charger, and Inverter / Charger.
5. Finally, wire up your point of use. This includes all DC appliances and AC outlets. Be sure to protect any wires running near sharp edges with conduit or sheath

Your camper van’s electrical system will be one of the more expensive systems in your van conversion. You will be spending a couple thousand dollars. A few ways to save money:

• Shop on holidays. Often manufactures have steep discounts on holidays such as Black Friday and Cyber Monday.
• Look into your states solar rebates!Some states offer rebates on solar systems installed on primary residences!
• Invest in quality, long lasting components. This one sounds a little counter intuitive; however, if you invest in quality components like Victron, your electrical system will last a lot longer than some more budget counterparts which means you’ll save money in the long run.
• Bookmark our list! We have a Complete List of All Van Build Components, and we maintain an up to date “Deals” page with all current deals!

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