A van without an electrical system isn’t much to write home about. In fact, you could almost say that an electrical system is part of what makes a van a campervan. Though a little daunting, installing your campervan electrical system is hands-down the most enjoyable and satisfying part of any build. A good electrical system begins in the design stage. In this guide, we will go over the planning process, starting with a look at wiring diagrams.
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Shane, the founder of The Van Conversion, is a campervan professional dedicated to helping people transform ordinary vans into homes on wheels. He has authored Roaming Home, and teaches The Van Conversion Course, guiding many people through their van builds. Shane also writes The Van Conversion Newsletter, where he shares practical tips and insights. After completing two van builds and living on the road full-time since 2020, he is passionate about sharing his expertise with others.
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Before we dive into campervan electrics, you may like a refresher on your knowledge (including amps, volts, watts, fusing, wire sizing, AC vs. DC, solar, and batteries). Check out our article on campervan electrics for a refresher.
Budget, Mid-spec, and High-spec Campervan Electrical Systems
In this guide, we will be walking through a high-spec campervan wiring diagram in-depth. The electrical components in this system make for a complete, fully-featured system. However, if you are after a more budget option, we have included shopping lists for a mid-spec and a budget system below. Note that these shopping lists don't contain auxillary components like wiring, fuses, and busbars. We'll discuss those later.
Budget Electrical System
 | 100W Solar Kit w/ Charge Controller A small solar panel and PWM charge controller |
 | Charge your leisure batteries while you drive your van |
 | Convert DC to AC so you can have mains plug sockets in your van |
 | A single lead-acid battery to power your campervan |
Mid-spec Electrical System
 | A decent solar setup with MPPT charge controller |
 | Smart battery-to-battery charger A much more efficient way to charge up while you drive |
 | Convert DC to AC so you can have mains plug sockets in your van |
 | Allows you to hook up to mains at a campsite |
 | A single lithium battery to power your off-grid adventures |
High-spec Electrical System
 | A large solar setup with MPPT charge controller |
| Smart battery-to-battery charger A much more efficient way to charge up while you drive |
| Convert DC to AC so you can have mains plug sockets in your van |
| Allows you to hook up to mains at a campsite |
| A large lithium battery to power your off-grid adventures |
How to Get Electricity in Your Van
There are three ways of getting power in your campervan:
Solar power takes power from sunlight through roof-mounted solar panels. A split charger hooks up to your van's starter battery via the alternator and allows you to charge your leisure batteries while you’re driving. Shore power allows you to hook up to the mains at a campsite or service station and charge up.
In the Roaming Home 2023 study, campervan owners were asked which electrical system they were running in their van conversions. 84% of people are running a split charger, 58% have shore power, and 78% have installed solar panels.
How is Electricity Stored in a Campervan?
Electricity is stored in 12V leisure batteries in a campervan. There are many types of leisure batteries, the most popular being AGM and lithium.
What Do We Use Electricity for in a Campervan Electrical System?
Most van conversions have two electrical systems: a 12V DC system, and a 110V/230V mains AC system. Most campervan appliances run through the DC system, including the fan, fridge, lights, and heater.
If you want mains plug sockets in your van (to charge a laptop, for example), you will need an AC system. An inverter is required to convert 12V DC electricity from your leisure battery to to 110V/230V AC electricity.
Solar Power
Let’s look at the solar power portion of our campervan wiring diagram.
Solar Panels
In this campervan electrical system, we have four 18V monocrystalline solar panels wired in series, bringing the total voltage up to 72V. The total wattage is 400W.
The positive and negative wires run through a solar cable entry gland in the roof. This is perfect for the 6mm² wire we generally use for solar cables. For simplicity, we recommend Renogy's solar panel kits which come with everything you need out of the box. Victron also offer kits incorporating their premium components.
Not sure about the size of your solar array? We built a solar panel sizing calculator to help you determine how much solar wattage you will need for your system.
Solar Charge Controller
The solar cable runs from our panels to our solar charge controller - a device which manages the solar power input and keeps the battery from overcharging. There are two types of solar charge controllers: MPPTs and PWMs. MPPTs are marginally more expensive, but improve solar charging of the battery by up to 30% per day. We generally find this increased performance well worth the extra cost. Our MPPT sizing calculator will help you decide on the capacity of your MPPT charge controller.
To protect our solar charge controller, we add a 40A DC double-pole miniature circuit breaker (MCB) to the positive cable running to the charge controller. A breaker is like a fuse that can be reset once it is tripped.
Busbars
We then run cable (typically 10 mm²) from the solar charge controller down to our positive and negative heavy duty bus bars (300A). Busbars are a way of centralising all the positive and negative wires in our system so that we can easily route onwards to the leisure batteries through one single cable. They keep our cabling neat and tidy.
On the way to the busbar, we will add an inline breaker to the positive cable to protect the batteries and other appliances.
Leisure Batteries
The last step of the solar system is running the busbars to our leisure batteries. We run a single positive and negative cable from each busbar to the leisure batteries. Our wire sizing calculator will help you decide on your cable gauges.
On the way to the batteries, we are going to install an isolator or kill switch on the positive line. This is a big switch that will cut-off all campervan electrics in an emergency. We will also add a 250A terminal fuse onto the cable as a last ditch effort to protect the batteries in case of electrical overload.
Some people will opt for a single leisure battery, while others will opt for multiple batteries, increasing their storage capacity. If you are using multiple batteries, make sure you wire them in parallel to increase capacity whilst keeping the voltage at 12V. Wiring batteries in series increases voltage rather than capacity. Read more about parallel and series wiring here.
In the Roaming Home 2023 study, we found that of those vans with either lithium or AGM batteries, 46% are using lithium batteries. Compared to even five years ago, this is a huge jump. The benefits of lithium batteries are substantial, even if they do come with a higher upfront cost. Read more about battery chemistries in our comprehensive guide.
I recommend getting a single 200Ah lithium leisure battery. This is one of the better purchases you can make if you plan on using your van for years to come. Renogy and Victron are both trusted manufacturers of high-quality lithium batteries.
To figure out what size leisure battery you will need you will first need to figure out your total daily electrical needs. Our load calculator will help you determine your energy consumption. Once you have figured that out, you can use our battery sizing calculator to select the perfect battery.
Battery Monitors
You can optionally add a battery monitor (sometimes called a battery management system or BMS) to your campervan electrical system. A battery monitor gives insights into the health and usage of your leisure batteries. It'll tell you your battery's current charge status and how quickly it's charging.
A battery monitor with a physical display is very useful, as is one with Bluetooth connectivity. Such 'smart' monitors, like the Victron SmartShunt, allow you to monitor your batteries from your phone.
Battery monitors are installed on the large negative cable running from your leisure battery to the negative bus bar. Then, run a small positive cable directly from the positive terminal on your battery to the monitor to complete the circuit.
This completes your solar system. With this done, you are ready for your first off-grid adventure. However, we're not finished yet. We're going to give this system some extra juice by installing both a split charger and shore power.
Split Charging
Split charging is another integral part of campervan electrics. We have a detailed guide on split charging, but we'll go over the basics here. Split charging connects your campervan starter battery to your leisure battery. This means that your leisure battery will charge while you drive. There are two primary methods of split charging: a voltage-sensitive relay or split charger, and a battery-to-battery (B2B) charger.
In the Roaming Home 2023 study we found that 55% of van conversions are still using voltage-sensitive relays/split chargers rather than B2B chargers. The high efficiency of B2Bs and their favourable performance with lithium batteries is sure to see them take over. In our budget system, we use a voltage sensitive relay (VSR). In our medium- and high-spec systems, we use a battery-to-battery charger.
The DC-DC charger is installed on both a positive and negative cable running from the van's starter battery to the leisure batteries. On the cable we typically install a 100A fuse, followed by the charger, followed by another 100A fuse. We also need to install a D+ connection. This is a connection from the battery charger to the ignition of the vehicle. Further instruction on how to do this will be in the DC-DC charger's manual.
Use our battery-to-battery charger sizing calculator to decide which capacity B2B charger is right for you.
Shore Power
The next part of the campervan wiring diagram is shore power (or mains hook-up). Shore power allows us to hook up to the mains and charge up at campsites and motorway services. I have found shore power essential to my van travels as I make heavy use of campsites in winter. We have a comprehensive guide on shore power, but we'll discuss the basics here.
AC electricity is dangerous and can kill due to its high voltage. There's nothing wrong with consulting a professional on your shore power installation. At the very least, I recommend getting a professional to verify your system.
First, we need to install a shore power inlet in the side of the van. This allows us to take 110V/230V AC power into the van from a mains socket outside. We should use 3-core cable (live, neutral, and ground), rather than just positive and negative 12V cabling.
We run 3-core cable from the shore power inlet to a double-poled consumer unit. A consumer unit is a distribution board containing circuit breakers. From here, we run cable in two different directions:
From the consumer unit, we run 3-core cable directly to a (double-pole or unswitched) mains plug socket. This allows us to power devices such as a laptop directly from mains when we are plugged in at a campsite.
From the consumer unit, we also run 3-core cable to an AC-to-DC battery charger or inverter/charger. This in turn runs to our busbars and on to our leisure batteries. The battery charger converts AC mains power to 12V DC power so that we can charge our 12V leisure batteries. It also monitors and regulates the inflow of electricity to ensure a safe system. We add a 40A inline breaker to the cable between the battery charger and bus bars to give some added protection.
Below is a wiring diagram for the shore power consumer unit, but make sure to check out our mains hook up guide for more information.
Campervan Electrics: 12V DC Appliances
Most of our campervan electrics are 12V, from the fan, fridge, and heater, to the water pump, lights and USB chargers.
The graphic below gives a breakdown of some of the most common electrical appliances, per the Roaming Home 2023 study. We did not include LED lighting in the study, as their installation is assumed.
Each appliance is fused appropriately from a 12V fuse box. The appliances also run through an optional but recommended switchboard so that we can easily switch appliances on and off.
To power these appliances, we could run cable from the busbars directly to the fuse box. However, a better solution is to run cable from our solar charge controller instead. This allows us to power our 12V appliances directly from solar when the sun is out, rather than always running through our leisure batteries. It also gives us some extra monitoring capabilities for our 12V appliances.
Run cable (typically 10 mm²) from the solar charge controller to the fuse box. Then run cable for each appliance to the switchboard (typically 2.5 mm²). Finally, run the same cable to each individual appliance. Use our wire gauge calculator to confirm your wire gauges.
One of the most common appliances we will wire up in a campervan are LED puck lights. You can learn all about LED campervan lighting in this guide.
To help you brainstorm some other appliances for your van conversion, check out our list of 30 campervan accessories.
Onboard 110/230V AC Power
The next part of the wiring diagram is onboard AC power. Whilst shore power allows us to power our electrical system with external mains power, having onboard AC power will allow us to use mains appliances anywhere we go. In order to facilitate this, you will need to install a DC-AC inverter which converts 12V power from your batteries into 110V/230V AC mains power. A 1000W or 2000W inverter will do the trick for most van conversions.
To install an AC system, run some thick cable (35 mm²) from your positive and negative bus bars to the inverter. Then, wire up a plug head with some 3-core cable and plug it into your inverter. Run the cable from the plug head to some double-poled plug sockets in the van.
Note: You may require a consumer unit, installed between the inverter and sockets. The addition of a consumer unit here is dependent on which inverter you have. Some inverters have built-in consumer units, called GFDIs, whilst others don't. Check the manufacturer’s instructions for specifics.
It's important that we size our inverter correctly. If you're using something like an electric kettle or blow heater that takes a lot of power, you need to ensure your inverter is big enough to handle it. Use our inverter sizing calculator to figure out exactly how big your inverter you will need to be.
In our 2023 study, we found that most people install a 2000W inverter. Check out our comprehensive guide on inverters to find out more.
How to Ground Van Conversion Electrics
Grounding your electrical system is an essential safety feature that protects your system from damage, fire, and explosions. In a campervan, the ground is the vehicle's metal chassis. You can use an existing ground point or install a new point in the chassis. You can then wire anything that needs grounding to that bolt. Run all grounds to the same ground point, and keep your AC and DC grounds separate.
Here is what you must ground in a campervan:
Starter battery (should be grounded already)
Negative bus bar - this grounds your leisure battery and the other components in the electrical system
Shore power consumer unit
Here is what you might need to ground (consult the manufacturer’s guidelines):
MPPT
Battery chargers
Inverter & inverter consumer unit
Conclusion
Take a deep breath; you made it through the whole campervan electrical system. My advice is to go through the campervan wiring diagram several times to wrap your head around it fully. As I mentioned at the start, you can get the campervan wiring diagram for free by joining the newsletter here. Make sure you check out our longform articles on specific electrical components, including solar systems, batteries, inverters, and shore power to get a complete picture.
Don't forget to subscribe to The Van Conversion Newsletter for everything you need to get started with your own van conversion (we'll send you a free wiring diagram when you join).
If you're looking for some guidance with your van conversion, you might be interested in our book Roaming Home, or in our online course The Van Conversion Mastery Course. You'll learn directly from our founder Shane how to convert a van into your dream home - no prior experience needed.
Until next time.