Campervan Electrical System Explained – Planning the Ultimate DIY Van Conversion

Understanding how a campervan electrical system works is one of the most important aspects of any DIY camper conversion. In this post, we’ll break down what you need to know to plan, purchase and install vital electrical components in your van! 

Much of the joy of living in a van comes from your ability to go off-grid to enjoy the beauty of the great outdoors. And while having a plan for your water system is an important factor in being able to extend your time boondocking, we’d say your camper van electrical system could arguably be just as important, if not more so.

As we put power first in much of our design for building a van, we’ve been able to build hearty battery banks with robust solar power systems that have enabled us to camp off-grid indefinitely in places that range from the lonely frontier in Alaska to pristine, sandy beaches in Baja.  

When you do it right, your van electrical system will not only give you the power your need to run things in your van, such as lights, fans and water pumps. It will also give you the ability to run extra things you want – from laptops and cameras to Instapots and Magic Bullet blenders. 

But if you don’t do it right, you can put yourself in danger. 

DISCLAIMER: Building an electrical system in your campervan can be intimidating. And we definitely recommend that you consult professionals for anything you do not fully understand or need help with on the install. This post is intended to give you the outline and basic guidelines for how your power system works, what components you need to consider including in your setup and the basics of how to install these components. It is not intended to be a guide or installation manual. 

AFFILIATE DISCLAIMER: This post contains affiliate links for products and services we recommend. For more information, read our full affiliate disclosure here.

An Overview of A Campervan Electrical System

Before we cover the basics of a campervan electrical system we want to go through what the most robust power setup may look like inside a van. From there you can determine which electrical components you want to include or not include. 

Your van’s power system could be broken into three sections, each of which serves a very important and distinct role. 

Power Storage

Campervan Electrical system setup with batteries, solar charge controller, bus bars and breaker switches

Power inside a van is stored in the form of 12 volt DC power (described below) inside what it referred to as your “house” battery. Note that this battery has other interchangeable names, such as “leisure battery” and “auxiliary battery.”

Battery storage capacity is managed in amp-hours. In effect, this is the amount of power available to run a device with a 1 amp power draw for 1 hour.

Common leisure battery sizes typically start at 100 amp hours, with the most common being 100 amp-hours. But it is possible to find batteries with 200 or more amp hours capacity.

To further complicate things, there are multiple types of batteries with different capacities. From standard flooded lead-acid batteries to AGM and lithium. For more on battery types, check out this post.

Because your vehicle is also your house on the road it is important to distinguish between your van battery (located in the engine compartment, used to start your van) and your house battery (located inside your van to run your “house” appliances). 

Confusing the two can cause significant issues. 

Your vehicle’s battery, or starter battery, operates all of the necessary electronic equipment inside and outside of your van whether you built out the inside or left it as a blank cargo van.

This battery is responsible for starting the vehicle, but also operating the radio, speakers, inside lighting and outside lighting- pretty much everything that runs when you drive a normal car. 

But when you convert your van into a home you must also add a “house” battery (or batteries) that will be used to power all of the appliances specific to your house. This will include fans, lights, radio, cigarette lighter charger and so forth.

You’ll also potentially use this house battery to create power in the form of 110V power that can run devices like laptops, cell phone chargers and smaller appliances that would normally be plugged into power outlets in your house. 

When you connect two or more batteries together you create what is called a “battery bank.” Depending on your budget, space and power consumption needs, you will want to invest in the largest possible bank of leisure batteries. 

An important step in understanding the difference between your vehicle and leisure battery is also in separating them from each other.

Because energy will always flow from a source of high energy to low energy, if these batteries are connected without the ability to disconnect them, then when your house battery runs low from using your inside appliances it will try to draw stored energy from your van’s starter battery. Thus you may try to start your van one morning and not have the ability to do so. 

A battery isolator is used in this case such that you can charge the house battery while the van is running but not drain the battery when it is not (more on this later). A DC-DC charger is another way to capitalize on a running vehicle engine as well.  

The Takeaway: Investing in the largest possible house battery bank will give you more capacity to power any electronic devices you may need or want.

Power Input

Now that you understand that your house battery is the heart of the primary electrical system in your van, it is time to look at 4 ways in which you can keep the batteries fully charged. We call this the power input consideration for your electrical system.  

Running your batteries too low will cause permanent damage to them and thus diminish your ability to recharge them and use appliances inside your van.

So in addition to having the best batteries you can afford coupled with the largest possible batteries you need to consider how you will keep them within healthy charge levels. 

Van (Alternator)

The first way you can recharge your house batteries is, quite simply, by driving. This is called split a split charge as you will charge 2 different types of batteries at the same time.

If you connect your leisure and vehicle batteries by way of a battery isolator or a DC to DC charger, then you are able to charge your house battery from excess energy from your alternator charging.

Using a split charge, the alternator will keep the battery in the vehicle charged to keep you driving down the road with the radio blasting and your brake lights working. But anything extra it produces can be transferred into your auxiliary batteries through the split charge relay.

The benefits are spectacular, particularly if you do a lot of driving around. 

Shore Power

As we’ll discuss in more detail below, having a 110V shore power inlet allows you to literally plug your van into a power source where you can convert it into 12V DC that will be delivered to and stored within your leisure batteries.

To do this you’ll need a device called a power converter. This is a common way most RVs keep up with recharging their batteries.

But it is less common among van dwellers usually because there is less opportunity for power loss in van living (smaller spaces = fewer things to use power), most van lifers enjoy living off-grid away from shore power and there are added expenses and space required for a power converter.

But by far the easiest and most reliable way to recharge your hose batteries is by having a shore power inlet.

Solar Power System

Solar panels and roof deck on top of a van

By far the most common way that van dwellers recharge their leisure batteries is by incorporating a robust solar panel system. At this point in time, solar panels and a decent solar charge controller are efficient and affordable enough that we’d recommend anyone considering van life to account for adding solar panels to your van.

Essentially solar panels are mounted on your roof (or portable ones are set by the side of your van) and they collect energy from the sun. You then wire solar panels into a solar charge controller.

The charge controller is connected to your batteries and the solar panels and it determined the state of charge of your batteries to determine how much 12V power they need and at what rate to return them to a full state of charge. Any excess energy is dissipated through the solar panels in the form of heat. 

Solar power is a great option because, like the vehicle alternator, it is passive. In other words, as long as the sun is shining you don’t have to consider recharging your batteries.

But unlike relying on your alternator, once you have installed your solar panel system there are no ongoing expenses as you have a 100% renewable form of energy. 

Generator

The last, and least common, was to recharge your house batteries is to install or carry a generator in your van. A generator converts a fuel source (typically gasoline or propane) into 110V AC which can then be converted into 12V DC to top off your batteries.

Generators are great accessories and almost always included in larger RVs. But when it comes to camper vans they are cumbersome and require additional fuel along the way. For the cost of a reliable generator, you can instead invest in a robust solar power system. 

The Takeaway: There are 4 ways you can recharge your leisure batteries. We’d recommend you plan to include your vehicle alternator and a solar panel system. Whether you opt to include shore power is up to you (described below). And we’d recommend that you stay away from reliance on a generator. 

Power Output

The last thing to understand about electrical systems in a campervan is the power output, which is how your electronic devices or appliances draw power to operate. This will either be in the form of 110V AC power or 12V DC power. 

As we’ve already discussed these in some detail already, we’ll get into more of the nuts and bolts of each in this section as a clear understanding of each is important to the planning and installation of your electrical system. 

Direct Current (DC) vs Alternating Current (AC) power

There are two forms of power inside your campervan. We’ll quickly cover both as you want to consider each when it comes to your van’s electrical system. 

AC Power

Alternative Current, or AC power, is your standard at-home power. It typically ranges between 110-120 volts, which makes it dangerous to work with.

However, it is essential if you want to run appliances in your van that you would normally run in your home. From smaller items like computer and camera battery chargers to larger ones like a blender or pressure cooker, anything that has 3 prongs and usually plugs into your home power outlet runs on AC. 

When it comes to camper vans and RVs, AC comes to play in the form of “shore power.” This is a 110V electrical connection that you make between your van and a power box at a campground or house. Power will typically be delivered from the source in the form of either 20, 30 or 50 amps into your van.

For larger RVs, 50 amps may be necessary to run all of the ac appliances and multiple air conditioners. So you can rule that out of your planning as it will be overkill for your van. 

But whether you opt for a 30 amp, 20 amp or no shore power cable at all is up to you. Most smaller RVs will include a 30 amp connection with the ability to “step down” to a standard house 20 amp outlet through the use of an adapter. 

But when it comes to camper vans, there is a wide range in whether van dwellers even want a shore power cable or whether to go with just a standard 20 amp connection that can be plugged in virtually anywhere there is a power outlet through the use of a standard extension cord. 

Inside the van, however, AC comes to play when you want to run the various ac appliances that require it. There are 2 ways to provide this power. 

First, have a shore power inlet so that you can plug in these ac appliances when you are connected. Note, they will only work in the event you are plugged in. But at least you have the option. 

Second, install an inverter with your battery that will allow you to transform the power stored in your batteries into 110V AC power. 

We’ll cover more on this topic shortly. 

Takeaway: You don’t need to include a 110V AC in your DIY electrical system. But regardless, you will want (and likely need) an inverter to be able to use 110V electronic appliances. 

DC Power

Direct Current, or DC, is the most important power inside any recreational vehicle and can be considered your primary electrical system. So you’ll want to fully understand its role and importance in your van build. 

DC power is stored in your batteries and is limited to the size and type of battery you install. As opposed to AC that runs on much higher voltage, DC is typically delivered at 12 volts. It is used to power 12V appliances inside your van such as your LED lights, fans and water pump.

DC operates in a loop, where energy leaves the positive side of the battery and flows along a path as long as it is uninterrupted. When it is interrupted, such as a blown fuse or tripped breaker, power will not flow.

Thus you will always want to protect your appliances from surges in power by adding a fuse block or breaker box along the positive wires in your power system. 

There are special power distribution centers that receive power from your battery and then distribute it through a handful of receptacles that have fuses on them. You’ll want one of these when you get to designing your DC system. 

DC is most essential inside a camper van as all of your house appliances rely on it. Even if you are plugged into shore power the 110V AC will be “converted” into 12V DC that will go into your batteries through a battery charger.

From there the power will run to your fuse box and/or any devices or appliances that you have connected directly to your batteries (see this post for optimal battery wiring). 

Takeaway: While you may need to make a decision about whether you want to run 110V shore power into your campervan, you won’t need to decide whether or not to include DC. This is a must. And while you can get along fine without AC, when it comes to DC you need it for virtually everything. 

Power Converter vs Power Inverter

As already referenced, there are two primary processes that take place between 110V AC and 12V DC: power conversion and inversion. 

In one case, 110V AC is “converted” to 12V DC inside a power converter (also known as a battery charger). Because they are integral and literally connected to the DC system, a battery charger is often packed into high-quality power distribution centers.

In this case, incoming 110V power is converted into 12V DC. Thus when you are plugged into shore power you are able to top off your batteries even if you have the LED lights and fan on. As you consume power from your lights, the 110V is immediately converted to 12V and delivered to the leisure batteries. 

At the same time, you are also able to run your 110V appliances directly on shore power if you have chosen to install 110V AC outlets. Thus having shore a power connection as part of your campervan electrical system is twice as beneficial because you can power all of your devices while simultaneously keeping your batteries full. 

On the other hand, a power inverter will take 12V DC stored in your leisure battery and “invert” it into 110V AC. At this point, you can plug 110V AC appliances into your inverter (which must be properly sized, see below).

Thus you do not need shore power in your van to power all of your electronic needs. BUT you do need DC as you can invert it into AC as needed. 

Unlike a battery charger, power inverters are usually sold as stand-alone units and require specific wiring considerations. 

Takeaway: By far, the simplest, and thus most common, electrical setup in a DIY campervan conversion involves including only a large battery and an inverter to create 110V AC as you need rather than including a shore power connection as well. 

Components of a Camper Van Electrical System

To further understand how a campervan electrical system works so you can properly plan for your DIY van conversion or upgrade your existing power system, it’s time to take a look at all of the electrical components involved in a comprehensive campervan electrical system to understand what they are and what they do. 

Note that not all of these components will be necessary for your build. We’ll indicate which ones are necessary with an asterisk (*). 

  • * Leisure battery (or batteries)
  • AC/DC power distribution center
  • * Power converter / battery charger
  • Power inverter
  • * Split charge relay
  • Battery monitor
  • Bus bars (both positive and negative bus bar)
  • * Breaker box / fuse block
  • * Adequate wire length and wire gauge
  • Solar power system

Leisure Battery

As previously referenced, your leisure battery is the heart of your electrical system. As such, it is worth investing a majority of your power budget into the highest quality and largest capacity batteries possible.

We recommend either lithium or AGM batteries instead of standard flooded lead-acid batteries. You can read more about each in this post.

Essentially both types of batteries are sealed, which makes them maintenance-free, able to be mounted in small spaces and in any orientation but upside down. They can handle bounding around and recharge relatively quickly.

A lithium battery can be discharged to 20% or lower and remain healthy while AGM batteries should not go below 40% battery capacity. But lithium batteries cannot be charged in temperatures below freezing unless they are properly insulated. 

AC/DC Distribution Center

If you elect not to include a shore power connection then you will only need a fuse block or fuse box. With power systems that include both AC and DC inputs, you can purchase a joint power center that saves space and money.

A DC fuse box will receive DC from the battery and allow you to distribute it to all of the appliances in your campervan by splitting it off into separate channels of wiring inside the fuse box. Each channel will have a fuse to allow for the protection of the device.

Thus power from your battery can be drawn by several devices or appliances at one time and the fuse box will send it out accordingly. 

An AC distribution center will almost always include a battery charger as well. This will take the 110V power input from shore power and convert it to 12V DC to direct it to the batteries. But it will also include its own breaker box where you can divide the power to different AC appliances or outlets.

If you plan to have an air conditioning unit, microwave, 3-way fridge or other large AC appliances each will have its own breaker. 

Because AC and DC interact in this same space you will find that one AC/DC distribution center will be the hub from which all of your power will leave to power up any AC or DC electronic device. 

AC Power Converter

As previously discussed, a converter takes a 110V power source and converts it to 12 volts to be distributed to the battery bank. From the battery, it can then be used to power all 12V appliances connected to the DC fuse box.

These are only necessary if you choose to install a 110V shore power connection in your camper van. 

DC Inverter or Battery Charger

A DC inverter does exactly the opposite of a battery charger. It takes 12V DC power stored in your leisure battery and inverts it into AC that can then supply power to your 110V electronic devices and appliances.

These vary in size by wattage ratings, with the most common sizes being either 1000W or 2000W. Note that there is a direct relationship between the size of an inverter and the required auxiliary battery capacity.

You can’t just slap a 3000W inverter on a 100Ah battery and expect to use it. Check out this post on finding the best power inverter and the correct size for your campervan build. 

Split Charge Relay

A split charge relay allows power to flow from your vehicle starter battery to your camper’s leisure battery when the vehicle is running. But it prevents power from flowing in this direction when you are parked.

In this way, you can charge your leisure battery while you are driving without risking running your vehicle battery out of power when you are not.

These are necessary additions to your power system if you want to charge your auxiliary battery while you drive.

Battery Monitor

Battery monitor and inverter on and off switch

A battery monitor is connected in line with your leisure battery to determine the state of charge of your battery. It will also detect the rate that you are using power and determine the rate at which you are inputting power from any of the 4 methods described above.

While they are not essential, we consider them incredibly valuable. They are quite affordable and many come with Bluetooth connectivity so you are able to quickly and easily see all the data related to your battery bank on your phone.

Be sure to check out this post to read more about the best options out there and what to look for when selecting one for your van build. 

Bus Bar

When it comes to physically building your campervan electrical system, a positive and negative bus bar will be invaluable for helping you to streamline your power outputs and inputs.

Essentially a bus bar is a piece of metal to which you attach your positive terminal and negative battery terminal. From there, you simply attach your positive and negative loads to the bus bar to distribute the power accordingly.

This allows you to keep your battery wires clean and organized. It also allows you to add additional power appliances to the bus (or busses) without having to continue to add them to the battery posts themselves. 

A bus bar should be considered essential to streamline electrical connections and keep your positive and negative wires organized.

Breaker Box / Fuse Block

A breaker and a fuse essentially do the same thing. When too much power tries to pass through the wire they break the connection, or “trip,” thus preventing power from continuing to flow.

This not only protects the device on the other end. But also it prevents your wires from overheating and thus causing a fire. Every appliance or load connected to your battery bank should have either a fuse or breaker between it and the battery.

With a DC distribution center, you will have a fuse block as part of the center. But with an inverter, for instance, you will want to put a fuse or breaker on the positive wire between the battery and inverter.

Likewise, if you add solar power, you will want a breaker or fuse on both ends of your solar charge controller. 

Appropriate Wiring & Connectors

We use the word “appropriate” because it is important to understand that you cannot simply attach your batteries and devices/appliances with whatever wire you have on hand. Investing in the proper sized wiring and wire connectors is just as important as investing in every other component – if not more so.

Inadequately sized wiring may not be able to handle the current (amperage) from devices trying to pull too much power through too little wire.

Think about water from a fire hydrant being pushed through a garden hose. The hose will simply explode under so much pressure. Your wiring is the same way.

Wires are measured in thickness by American Wire Gauge (“AWG”) size. Generally, the wires between your batteries will be substantial in size. As will the wires between your battery and inverter.

But your various DC appliances, such as lights, fans and water pumps, do not require as heavy gauge wire. 

For more information on how to determine the correct wire size, see this resource

Solar Power System

A solar system is an entirely different, but interconnected, power system that operates in the same fashion as your van’s electrical system.

Essentially you will install solar panels on your roof as this is the best place for them to collect energy from the sun. That energy will flow into your van to a charge controller that will then direct as much or little of the solar energy to your battery bank as the batteries required.

While the system itself is relatively simple, there are a variety of components and considerations to take before you install solar. For more details, be sure to check out this post where we walk you through each component and how to install the solar system. 

Campervan Electrical System Setup Options

Depending on how complex you want your power system to be, you can add to or take away from much of what we have discussed thus far.

In this section, we’ll provide 3 quick template setups offering you an idea of the different power arrangements you can plan for in your camper van. 

Bare Bones DC-Only

If you’re looking for a minimal electrical setup for your campervan then this is a great starting point in your planning process. 

Key features: This system will include everything you need for the basic operation of electronic devices and appliances inside your van, including an inverter to generate 110V power. But you will not include a shore power connection or solar power system. 

  • Battery charger
  • 100 Ah Lithium or 200 Ah AGM battery bank
  • 1000W power inverter (+100 amp breaker)
  • Monitor
  • Split charge relay

Robust DC + Solar

If you’re looking for a slightly more robust DC-only electrical system that incorporates solar then this is a great starting point in your planning process. 

Key features: This is more a robust power system that provides you more battery storage capacity, a larger inverter for more 110V AC-powered devices and a basic solar panel system to keep your battery bank topped off.

It does not include a shore power connection but does include higher-quality lithium batteries. 

  • Battery charger
  • 200 Ah Lithium battery bank
  • 2000W Power Inverter (+200 amp breaker)
  • Monitor
  • Split charge relay
  • 200W Monocrystalline Solar Panels
  • 30 amp MPPT Solar Charge Controller

AC + DC + Solar

If you want to have all the power you could need under most circumstances you will face on the road, this electrical system will leave you wanting for nothing. 

Key features: The most complete campervan electrical system, this electrical setup will combine both AC and DC inputs, a large lithium battery bank and a robust solar system capable of keeping you powered up even with heavy electronic use and a streak of cloudy days. 

  • AC/DC Distribution Center
  • 30 amp shore power connection
  • 200 Ah Lithium battery bank
  • 2000W Pure sine wave power inverter (+200 amp breaker)
  • Monitor
  • Split charge relay
  • 300-400W Monocrystalline solar panels (depends on how many solar panels you can fit)
  • 40 amp MPPT solar charge controller

Wrapping Up

Your campervan’s electrical system can be as complex or simple as you would like it to be. In each of the above van life scenarios, you can even increase your battery bank capacity and solar panel system or leave things as simple as possible.

A key thing to remember is that you should have an idea of how much energy you think you will need before you design your wiring diagram for your electrical system. And that it is always better to invest in larger and more efficient batteries than anything else on the list. 

We encourage you to use this post as a starting point in your design and to research specific products and components before installing your electrical system.

Hopefully, we’ve provided you with more than enough information and additional resources to help you get started in designing the perfect electrical system for your campervan needs! 

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