Campervan Electrical System: How to Plan It So You Don’t End Up in the Dark

Alright. You’ve got the van. You can already picture the bed, the kitchen, the storage, maybe even that little table where you’ll sit with your morning coffee overlooking the mountains.

And then comes one of the less exciting parts of the whole conversion.

Electricity.

How big should the battery be? How much solar do I need? Do I need an inverter? What about the cables? What if I want induction cooking? And where am I supposed to fit all of this?

If your answer to all of that was “we’ll figure it out somehow,” welcome to vanlife. 😄

Electricity is one of those things that’s really easy to plan on paper and surprisingly annoying to deal with once your furniture, walls and half the van are already screwed together. So before you pick up that drill, let’s talk about what’s actually worth thinking through.

First, forget about the battery

It might sound strange, but don’t start by asking how big your battery should be. Start with what you’re actually going to use inside the van.

There’s a pretty big difference between someone who just wants lights, a fridge and a way to charge their phone, and someone who wants to work from the van with a laptop, coffee machine, induction hob, hair dryer and maybe even air conditioning.

So make a list. Lights, fridge, USB sockets, water pump, fan, heating, laptop, camera, coffee machine, induction hob… whatever you think you’ll use.

And yes, put the coffee machine on the list too. If you know you want one, it’s better to plan for it from the beginning than discover after finishing the electrical system that your morning espresso is basically a small energy crisis.

Watts are not the enemy

Once you start looking at appliance specifications, you’ll see W, V, A, Ah and probably wonder whether buying a ready-made campervan would actually be easier.

It’s not that bad.

For starters, the main thing you’ll want to look at is power in watts (W) and, more importantly, how long you’ll actually use each device.

For example, a 10W light running for four hours uses roughly 40 Wh per day. A 60W laptop used for three hours adds another 180 Wh. And you can work your way through the rest of the van the same way.

The important part is the combination of power and time. Something with a high power draw that you use for ten minutes can consume less energy overall than something with a low power draw that runs practically all day.

The fridge is a good example. Its compressor doesn’t run constantly, so simply taking its maximum power and multiplying it by 24 hours won’t give you a particularly useful estimate. It’s much more helpful to look at its expected daily energy consumption.

And this is where your electrical system really starts to take shape.

12V or 230V?

Another classic question.

And the answer is: it depends on what you want to run.

A lot of campervan equipment can run directly from 12V – lights, fans, water pumps, some fridges, USB sockets and certain heaters, for example.

Then there are the things you know from home. Coffee machines, hair dryers, some kitchen appliances or devices with standard 230V chargers.

If you want to use those when you’re not connected to shore power, you’ll probably need an inverter.

And this is where it’s worth stopping for a second.

An inverter takes energy from your battery and converts it to 230V. The more powerful the appliance you run through it, the more demanding the whole system becomes – your battery, cables and inverter included.

Take a 1,500W induction hob, for example. In a 12V system, that’s theoretically around 125 amps, before even taking inverter losses into account.

So if you already know you want to cook with electricity, tell your future electrical system about it from day one.

Not after everything is finished.

So how big should your battery actually be?

Battery capacity is usually given in Ah – amp-hours. You’ve probably seen 100Ah, 200Ah or even larger batteries.

The problem is that Ah alone doesn’t tell you the whole story. As a basic approximation, you can calculate energy like this:

Wh = V × Ah

So a 12.8V battery with a capacity of 100Ah has a nominal energy capacity of roughly 1,280 Wh.

That doesn’t mean you can simply use all 1,280 Wh under every condition. It depends on the battery chemistry, its specifications and how the system is operated.

And most importantly, you don’t automatically need the biggest battery you can find.

If you use relatively little energy and drive every day, a smaller system might be perfectly fine. If you want to spend several days off-grid, work from your laptop and cook electrically, you’ll obviously need a different setup.

So instead of asking:

“How big is everyone else’s battery?”

ask:

“How much energy do I actually need?”

And what about solar?

How much solar power do you need? 200W? 300W? 400W? 600W?

Honestly, there’s no magic number that works for everyone.

A solar panel doesn’t produce its maximum rated output all day. Actual production depends on the weather, season, daylight hours, shade, panel orientation and where the van is parked.

So 400W of solar doesn’t mean you’ll be producing 400W all day long.

At the same time, solar can be a brilliant way to keep topping up your battery when you’re staying off-grid.

And this is where it’s worth thinking about how you actually travel.

If you drive somewhere every day, you’ll have opportunities to recharge while driving. If you park next to a lake for several days and the van doesn’t move, solar becomes much more important.

The battery needs to be charged somehow

This sounds obvious, but it’s easy to forget when you’re busy choosing batteries and solar panels.

You can charge your battery through solar, while driving, from external 230V shore power, or through a combination of several methods.

For charging from the vehicle, many modern vans use a DC-DC charger, which provides controlled charging of the leisure battery from the vehicle’s electrical system.

And again, the exact solution depends on your van and your components. A modern vehicle isn’t always just “battery + cable + alternator.”

And now for the important part: where does all of it go?

This is where you can really tell the difference between a well-planned campervan and a “we’ll find somewhere for it” campervan.

The battery needs space. The inverter needs space. The fuse box needs space. The solar controller needs space. And the cables need somewhere to run.

Suddenly, that space under the bed that you originally wanted for shoes and camping chairs looks like the perfect home for your electrical system.

And that’s exactly why you shouldn’t plan the electrics after the interior is finished.

Electricity, water and furniture should be planned together.

The fridge is in the kitchen? Great. Where does the cable go?

You want a USB socket next to the bed? Where will the cable run?

You’ve got a light above the kitchen? Where’s the switch?

The battery is under the bed? Can you actually access it if you need to inspect or replace it?

These questions are incredibly easy to solve on a drawing.

They can be a lot less fun once the furniture is finished.

Cables are not something you just “figure out later”

Your wiring needs just as much thought as everything else.

You need to consider cable length, conductor size, current, voltage drop, routing and appropriate fusing.

In a 12V system, voltage drop can become especially important, particularly with higher-current devices and longer cable runs.

So the idea of “some red cable and some black cable should probably do the job” isn’t exactly the best design strategy.

The same goes for fuses. You don’t want to put everything behind one huge fuse just because it seems easier.

Individual circuits should be designed and appropriately protected according to the specific equipment and wiring.

And if you’re not sure, this is one of those moments when getting advice from someone who knows what they’re doing is absolutely worth it.

And then there’s 230V

If you’re planning standard 230V outlets in your campervan, this is where we definitely wouldn’t recommend experimenting with the “I watched a YouTube video, so I’ve got this” approach.

A 230V installation has different safety requirements from a simple 12V circuit. It can involve shore power, protective devices, RCDs, circuit protection, outlets, an inverter or a charger.

The exact setup needs to match the equipment you’re using, the way it’s installed and the relevant safety requirements and standards.

If you’re not confident with this part, get it designed or checked by a qualified electrician.

Draw the whole system

It doesn’t have to look pretty. You don’t need CAD software or an electrical engineering degree.

Just draw what connects to what:

SOLAR → CONTROLLER → BATTERY → FUSE BOX → LIGHTS / FRIDGE / PUMP / USB

And if you have an inverter:

BATTERY → PROTECTION → INVERTER → 230V

And charging while driving:

ALTERNATOR → DC-DC CHARGER → LEISURE BATTERY

Even better, put all of this directly onto your van floor plan.

Because that’s where reality starts to show itself.

Battery here. Fridge there. Fuse box over there.

Wait…

That cable has to run across half the van.

Exactly the kind of thing you want to discover before you start building.

And don’t forget about weight

Electrical equipment weighs something.

The battery, solar panels, inverter, chargers, cables, fuse boxes…

And then you still have water, furniture, kitchen equipment, bed, gear, luggage and, of course, yourselves.

One kilogram at a time, it all adds up.

So when planning your electrical system, think not only about how much energy you need, but also how much the system weighs and where that weight is located.

So, where do you actually start?

If we had to give you just one piece of advice about campervan electrics, it would be this:

Don’t start shopping. Start planning.

First, think about how you’ll use the van. Then list everything you want to power. Estimate your daily energy consumption. Decide how you’ll recharge the battery. Think about 12V and 230V. Decide where the battery and other components will go. Draw your electrical system and then connect all of it with your interior layout.

Only then start buying things.

Because there’s nothing worse than having thousands worth of beautiful electrical components sitting in your garage and then realizing you have nowhere sensible to put them.

And that’s exactly why it makes sense to plan your electrics together with the rest of the interior.

Bed, kitchen, storage, water, electricity, walkways… everything is connected.

Before you pick up that drill…

You don’t need every single screw figured out from day one. But you should have a pretty good idea of what goes where and why.

That’s the beauty of a DIY campervan conversion – you can build it around exactly how you want to travel.

But it’s also a little bit like putting together a puzzle where every piece affects several others.

The bed affects your storage. Storage affects the battery. The battery affects the wiring. The wiring affects your furniture layout.

And suddenly you’re rebuilding half the kitchen because you forgot one socket.

That’s why it makes sense to have a plan before you cut the first piece of plywood.

At CamperLayout, we help DIY builders plan campervan interiors around their specific vehicle and the way they actually want to travel. The design can take into account things like the electrical and water systems, component placement and the other important parts of the conversion.

Because a good conversion doesn’t start with a saw.

It starts with a plan.

And the better the plan, the better the chance that you’ll end up with a campervan you actually want to spend time in.

Not one you spend every other Sunday fixing. 😄