Create An Off-grid Campervan Electrical System (DIY Beginners Guide)

Written By:
Bradley Williams
/
Last Updated:
June 20, 2021
Designing a campervan electrical system if you have no prior experience is super confusing! So here is the beginner guide I wish I could have read ...
Our campervan electrical system
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Throughout our entire van conversion, the most stressful and worrying part was sorting out the campervan electrics.

Why?

Because I knew absolutely NOTHING about how electrics work.

No matter how much I read and researched I simply couldn’t get my head around it and was worried about where to even begin with creating a campervan electrical system.

2 months later, I’m sitting here in Scotland writing this guide and I honestly believe we have one of the most epic systems around!

We are so happy with how our system turned out, and we are totally off-grid, not dependent on any sort of hookup in order to power our electronics.

Below, I’m going to take you through the exact setup we have in place and why each element is important.

Whether you need something as beefy as our setup, or something smaller, this beginner's guide should give you a clear understanding of what you NEED to know.

But to be clear, this is not 100% technically correct.

In fact, if you’re a professional electrician you’ll probably be shocked by some of the simplifications I make (this is for beginners, not you pros).

It’s the sort of guide I wish I had access to when starting out with designing the electrics in our campervan.

TAP TO INTERACT

Creating an off-grid campervan electrical system

For us, creating a van that is fully self-sufficient was extremely important.

That’s because we work full time on the road, and need a way to ensure we can charge all of our devices all the time and never need to plug into a shore power outlet.

After 2 months in the van, we have not once run the batteries down, and have used a LOT of juice.

On a daily basis, here are the sorts of things we use in the van:

  • Charging 2 travel laptops
  • Running a 1200 watt coffee machine
  • Boiling water in our Malaga 5E
  • Powering 10 ceiling lights
  • Running a fridge all day
  • Charging travel drone, camera, GoPro and other devices

How do we manage this?

Just keep reading!

Which batteries do you need for a campervan?

Batteries are what your entire campervan electrical system will be dependent around.

They are what power all of your appliances so it’s important you buy the right ones.

First up ...

12v vs 240v (110): What’s the difference?

240 volt is essentially mains household power.

Whenever you plug an appliance in at home, 240 volts is the power that then runs through to your device.

Depending on which country you’re from, you may have a different mains voltage, such as 110, 120 or 130.

The same principles apply, so whenever I mention 240 volt throughout this article, just switch this for your local voltage.

Whenever you buy a typical household appliance, say for example a coffee machine or a television, they require this 240 volt power supply in order to run.

On the flipside, 12 volts is the power you get whenever you run a device off a battery.

***DISCLOSURE: This is not 100% true as you can get batteries for your camper that run on 24 volt. I am not entirely sure on the difference between 12v and 24v, but 12v is the most common batteries used and it is easiest to get 12v electric kit for campers***

Here is a simplified rundown of what your eventual system will look like.

  1. Ways to generate power, such as solar power (more on this below)
  2. This power goes into your battery bank
  3. This distributed 12 volt power out to all the appliances hooked up
  4. An inverter (more on this below) converts 12v to 240v and allows you to plug devices into sockets
12v fuesboard camper electrical system
Our 12v fuseboard is what all of our appliances run through (except those that use 240v)

How much battery power will you need?

Okay, you’ve probably now got even more questions than when you began reading this guide!

But hang in there and stay with me.

The first step in designing your camper electrical system is to decide how much battery power you will realistically need.

To do this, you calculate how many amps of power you use on a typical day.

On many appliances, they will tell you how many watts or amps they use, and from this you can then calculate the total number of amps used.

For example:

  • Our coffee machine uses 1100 watts of power
  • When I convert this to amps I find that it uses 91.67 amps per hour
  • I anticipate that I need to use this coffee machine for roughly 10 minutes per day
  • 10 minutes is 0.17 hours
  • So 91.67 amps x 0.17 is 15.28

This means that our coffee machine uses 15.28 amps every day (on average)

We went through and did this calculation for absolutely every appliance we would need.

For us, this included things like:

  • Our laptops
  • Our drone batteries
  • Coffee machine
  • Ceiling lights
  • Fridge

To get an accurate idea of how much total amps you will require, we used a spreadsheet created by Explorist which I highly recommend. 

You can find it here.

What size batteries will you require?

220ah AGM camper leisure batteries

One of the crucial things to know about batteries is that they should never be run below 50% of their power.

Why?

Because this effectively ruins them and they will struggle to properly reach full charge again.

This is true for the batteries that we (and most van converters) use; which are called AGM batteries.

There are different types of batteries out there, such as lead-acid and lithium-ion.

Lithium ions are the best money can buy, and aren’t subject to the same 50% rule; however they are currently VERY expensive.

Which is why the vast majority of people opt for deep cycle AGM leisure batteries.

Assuming you opt for these, then to calculate what size you need, simply multiply your average daily usage by 2 (this counteracts the 50% rule).

For example, if you use 100 amps a day, then you will need a 200amp hour deep cycle AGM leisure battery.

That way, say your battery starts the day full, then by the end of the day it will have fallen to 50% of its charge, at which point it needs to be recharged.

Make sense?

Okay great, but don’t worry you don’t need to find a way to charge your batteries each night.

Instead, with an off-grid system your batteries will be getting charged continually throughout the day, both through solar power and a split charge relay/b2b charger (more on that below).

For now, the important point is that you need to calculate exactly what size batteries you need, as this makes the next steps a lot easier.

What did we opt for?

After we did our calculations, we found that on the high end we would use roughly 200-220 amps of power every day (which is quite a lot).

(To be honest, I don’t think we have ever hit this yet, but it’s proved great to have much more battery power for times when the batteries can’t get fully recharged every day.)

We looked for the biggest beefiest batteries we could find and bought two of them.

So our campervan battery setup includes these 220 amp hour deep cycle AGM leisure batteries.

They each weigh roughly 65kg (a person) and are AWESOME!

When connected, they give us 220 amp hours of charge and have proved exceptional.

If you are a bit worried about running out of charge, then it may be a good idea to buy a bit more than you need.

For example, if you think you’ll use maybe 60 to 80 amps a day, then realistically, a 160 amp hour battery will be fine.

But if you can afford to spend that little bit more and get the 200 amp battery, then you know that even on days where your batteries don’t get much charge into them, you shouldn’t experience any problems

How much solar power will you need?

Our off-grid solar setup!

Once you know what batteries you require, everything else starts to fall into place.

The next step is to calculate how much solar power you require.

Why solar power?

Because it’s free and charges your batteries without you needing to give them any attention.

Plus, who doesn’t want solar panels on their roof! It’s cool!

What size solar panels should I get for my campervan?

There is no exact rule here, as it depends on a number of different factors, namely:

Where your van will be and how much solar it receives.

If your van is set to be parked up in Italy in the middle of summer all day with zero shade, then you will require much less solar than someone parked up in Ireland in the middle of winter.

In our case, the plan is to live in our van full time and drive around the world.

Meaning that we will encounter all circumstances.

As such, we went all in and fitted as much solar as possible based on the available roof space on our van.

This amounted to 3 x 160 watt panels from Sunshine Solar.

We shopped around and these panels perfectly maxed out space on the van, and came in at the most reasonable price (£115 for each panel).

We had a great experience buying through this company as we had to call in a few times for advice and they were super helpful and really easy to get a hold of.

We also bought a few other pieces of necessary kit and the guy I spoke to did a sort of bundle deal.

As such, I recommend calling in as well.

If you are only installing a small leisure battery, then 480 watts of solar is very excessive and is more than you’ll need.

It may be a good idea to speak to the guys at Sunshine Solar or another company and they could advise you on how much you need.

Other key components of solar power

In order for your solar panels to charge your leisure batteries, the charge from them needs to first go through a charge controller.

I don’t 100% understand how they work, but my understanding is that they convert the power from the panels and turn it into the right sort of power in order to charge your batteries (technical explanation I know).

What I do know is that not all charge controllers are born equal.

Your best bet is to buy an MPPT (Maximum Power Point Tracking) which is the best at maximising the power taken from your solar.

It also helps protect your battery bank by not overcharging them (which would be an expensive malfunction).

We went for a 40amp MPPT from Epever which came with a handy battery monitor for inside the van.

I see this model pop up an awful lot in discussions on the topic, so it’s a well-trusted one to get and has proved great for our purposes.

If you have less solar, then I don’t think you need such an expensive MPPT; again Sunshine Solar or a similar company can advise you on what size charge controller to get, based on your chosen setup.

MPPT solar charge controller

How to install solar panels in a van conversion

You have two main options here:

  1. Install them directly onto the roof of your van using mounting brackets
  2. First, attach a metal roof rack onto your van and then fit your panels onto this

We went for option 1, and it has turned out fine.

However, looking back I would be tempted to opt for option number 2 as in the future this would make the task of replacing solar panels a lot easier.

For a look at how we mounted our panels, I recommend checking out this video in our van build series:

One thing to note is that, instead of pushing the plastic blocks down onto the adhesive, as you do when bonding most things, you should instead create a thicker bed of adhesive and allow the brackets to sit and dry into these.

We learned this the hard way as, just a couple of days after mounting ours, half the brackets came loose as the Sikaflex below simply cracked away.

I then had to re-stick them, and also went through and put a bolt through each one into the roof itself.

It’s absolutely fine and they have held up great ever since, however, the bolts probably wouldn’t have been necessary if I had known how to use the adhesive properly.

Live and learn.

Installing a Split charge relay vs B2B charger

Now that we’ve covered solar, it’s time to cover the other main way your van’s batteries can get charged up: battery isolators (split charge relay) and B2B chargers.

Without getting technical, they are similar things and simply connect up your van’s starter battery (alternator) to your leisure batteries.

Then, when you are driving, the starter battery will charge your leisure batteries.

The actual unit itself is wired in between the two and helps to regulate the charge passing through.

They only allow charge to pass when the starter battery goes above a certain voltage (around 13volts usually).

They then stop letting charge through when the voltage drops below a certain point (around 12.6 volts).

In doing so it helps protect the starter battery and stops it from getting drained down.

Do you need a split charge relay or B2B charger?

It depends mostly on how big your leisure batteries are.

A split charge relay is cheaper and can be installed when your leisure batteries are up to around 220 ah.

Anything above this and a battery to battery charger is necessary.

B2B chargers are more effective in general, both at passing more energy through from your starter motor and at using it in a more efficient manner.

If you’re not sure which one is best for your setup, I recommend you ring a store and one of the experts can advise you, this is what we did with Simply Split Charge.

Best Split charge relays

There are a few different brands to choose from, but two popular ones I see discussed a lot are Durite and Cargo.

Best Battery to Battery chargers

You can get different size B2B chargers, and you may need to get a certain one if your van is Euro 6 or above.

After a lot of research we opted for the 60 amp Sterling B2B, which is widely considered the best around, and is also compatible with Euro 6 engines and above.

So far, it has been excellent!

Shore hookup

The third and final way to charge your batteries is through a shore hookup.

This is the 240v plug inlet that goes in the side of your van and allows you to plug in at campsites, or even through a household mains supply.

We have one of these on our van, but it is purely there for emergency purposes as we hope never to really need it.

If you wish, you can install the shore hookup point, and then some sort of changeover switch that allows you to run off this mains hookup whenever your van is plugged in.

If you want this to actually charge your leisure batteries, you will need to install a battery charger.

Oh yeah, and be sure to grab a campervan hookup cable.

What appliances will your van need?

This is completely up to you!

Feel free to get creative here and think outside the box.

Plenty of people have things like TV’s, coffee machines, CCTV and even Playstation’s / Xbox’s in their campers.

Just think about exactly what you want and then work back from there.

For a full list of all the appliances we installed in our van, scroll to the end of this post where there is a full parts list. 

Generating 240v electricity in your van

For this, you will need an inverter.

An inverter is a device that connects to your batteries and converts the 12v DC current to 240v AC current.

This 240v AC current is what’s needed to power standard household electronics, such as your televisions.

In our van, we have a 1500 watt inverter that goes to 3 places:

  • A double gang plug socket by the bed
  • A double gang plug socket in the living area
  • Our water heater

This is perfect for us, as it means an appliance can be plugged in anywhere it is needed.

There is also a plug socket on the side of the inverter, so if we ever needed to plug something into the garage space of the van, then we could use this.

How do you know which size inverter to buy?

Base it on the highest wattage appliance(s) you are likely to use.

For us, our highest wattage appliance is our coffee machine which comes to 1200 watts.

The 1500 watt inverter is perfect as it runs no trouble.

However, we couldn’t, for example, run the coffee machine at the same time as boiling water on the water heater using the 240v option.

This is because the total wattage passing through the inverter exceeds 1500 watts so it trips.

Other than this, we can run the water heater and charge both laptops and a phone and the inverter never cuts out, so 1500 watts was perfect for us.

Buying an inverter

As with most things, the more you spend on the inverter, the better it should be.

We have the 1500 watt Novipal inverter which cost us £180, which is on the cheap end for this size inverter, but had fantastic reviews.

If you want to run something heftier, like a microwave, then you’ll likely need a 2000 watt or maybe even 3000 watt inverter; but don’t expect them to come cheap.

If you find an inverter for sale on Amazon, claiming to be 2000 watts but it’s only £40 and has no reviews, avoid it like the plague.

Be sure to buy one that is “pure sine wave” and has plenty of genuine reviews and recommendations.

Wiring everything together

An eagle-eyed reader would probably be saying at this point:

“Okay Bradley, all of this advice is great, I’ve just spent over a grand on equipment but how the heck do I install it all!”

Well, my advice here is very simple:

PAY SOMEONE TO DO IT FOR YOU!

Unless you are a qualified auto electrician, you shouldn’t be installing these electrics in your van yourself.

Even if you have tonnes of experience in household electrics it doesn’t matter as caravan and motorhome electrics are a different ballgame entirely. 

If you mess something up, you’re at risk of damaging the components and losing hundreds of pounds in gear, or worse, causing a fire.

You may also find that it invalidates your insurance as the equipment was never professionally installed.

Finding an auto / motorhome electrician

We spent a lot of time searching online and calling as many local auto electricians as possible.

We also spoke to some full-time camper converters who specialise in this sort of thing.

What did we find?

The experienced van converters will RIP YOU OFF!

We were quoted as much as £2,000 to have our campervan electrics installed, with some claiming the work would take 2 to 3 days.

This was an absolute lie.

In the end we settled on a local guy who took a grand total of 7 hours to fit absolutely everything.

He charged us £60 an hour, which amounted to a grand total of £420.

Seeing as the electrics we installed totalled closer to £2,000 it is definitely worth it.

We ended up with a much more professional build and saved a heck of a lot of time by not trying to do everything ourselves.

My advice would be to get as many quotes as possible, but also to source absolutely everything yourself, so that you can’t get ripped off.

Google is your best bet here, simply search for “auto electricians near me” and “van converters near me”.

You may also like: Our Campervan Water System

My top tips for installing electrics in a campervan conversion

1. Bring in professional help

Covered above, but thought it’s worth mentioning again!

2. Create a campervan wiring diagram

To help in finding the right campervan electrician, and also having the best system possible, it’s worth creating a motorhome wiring diagram that accurately lays out where you plan to put everything.

This helps you in knowing exactly what to buy, as well as how much wire you will need to run for each component.

3. Understand what’s going on

When your electrician is there installing the electrics, it is worth helping out for the entire job.

Not only will it save a bit of time, but more importantly it means you get to see exactly how everything comes together.

We asked tonnes of questions during our install and the guy was super helpful.

In the end, I now have a pretty solid idea of how everything works and can fault fix simple things when on the road.

4. Buy all your appliances before running wires

Before getting started actually running wires, I recommend buying absolutely everything that you plan on fitting.

It is much easier to move things around before wiring than it is afterwards!

5. Put your control panel near the bed

One of my favourite things about our install is that the main control panel for everything is right next to the bed.

This means that we can control anything we want from in bed.

Forgot to turn a light off? Simply reach over.

Want to work in bed? Plug your laptop in right there!

Waking up to a cold morning? Just lean over and switch the heating on! 

Bliss …

Campervan electrics control panel
Our main campervan electrics control panel right next to the bed!

Upgrades we are keen to make in the future

The great thing about converting a van into a campervan is that there is always room for minor upgrades and improvements over time.

Trust me, you will feel the same way after your build is done!

Here’s a few things we have since learned about and are keen to install in our van in the not-so distant future.

  • Data signal booster - These go on the roof of the van and are able to massively improve the quality of your data connection. Apparently, even when you have no date signal, these things allow you to stream as if on a home WiFi network! Perfect for us as we always use our mobile hotspot for work but the signal strength is sometimes not good enough for heavy tasks.
  • Projector - Our plan is to install a travel projector and screen somewhere in the living area of our van. That way, we can chill and watch movies on the big screen, and when we’re done simply fold everything away!
  • Heat pads in our water tanks - If you plan on heading to colder countries, which we will, then if the temperature drops low enough, any underslung water tanks will freeze up and become unusable. You can get small 12v heating pads that go on the outside of the tank and help stop this from happening.

Camper electrical parts list

Here is an exhaustive list of everything we used in our campervan electrical system (plus links to where you can buy them … you’re welcome!).

You may require a few other fittings, clips or thicknesses of wire; it all depends on the appliances you choose to install, as well as how far they are from the batteries/fuse board.

The best person to advise you on this is a professional auto-electrician.

If there’s anything you think we may be missing, just drop a comment below.

Batteries

  • 220 amp AGM deep cycle leisure batteries - UK / USA
  • 60 amp Sterling B2B charger - UK / USA
  • Battery terminals - UK / USA
  • Battery terminal covers - UK / USA

Solar

  • 160 watt solar panel - UK / USA
  • 40amp MPPT solar charge controller - UK / USA
  • Junction box - UK / USA
  • Mounting brackets - UK / USA

Shore hookup

  • Inlet - UK / USA
  • Battery charger - UK / USA
  • Campervan mains hook up cable - UK / USA

Appliances

  • 1500 watt inverter - UK / USA
  • Propex Malaga 5E water heater - UK
  • Propex HS2000 air heater - UK
  • Maxxair MaxxFan - UK / USA
  • Coffee machine - UK / USA
  • Shurflo 30psi water pump - UK
  • Waeco/Dometic CRX80 2 way compressor fridge - UK
  • USB chargers - UK / USA

Lighting

  • Reading lights - UK / USA
  • Ceiling lights - UK / USA
  • Bathroom light - UK / USA
  • Kitchen lights - UK / USA

Wiring

  • Solar cable - UK / USA
  • 16mm battery leads - UK / USA
  • 1.5mm cable red
  • 1.5mm cable black
  • Wiring crimp connectors - UK / USA
  • B2B wiring kit - UK

Other

  • 12v fuse board - UK / USA
  • Blade fuses - UK / USA
  • Plug sockets - UK / USA
  • Switches - UK / USA
  • 6 metre jump leads - UK / USA
  • Carbon monoxide alarm - UK / USA

Planning your camper electrical system

I hope this guide has been of use, it definitely would have helped me when starting out.

Of course, everything won’t make sense immediately. 

Just know that it will eventually!

Once you start buying things and speaking to an auto electrician who understands 12v campervan electrics, you will have a much better idea of what is needed and they can help guide you in case you forget anything.

One last disclosure ...

DO NOT take my words here as professional advice, far from it!

It is simply my take on our setup and you should not attempt to install without the help of an auto electrician.

If you have any other questions about the electrical setup in our campervan, then just drop a comment below and let me know!

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