Motorhome advice: How to add a 12V socket to your motorhome or campervan
Our campervan is based on a 1986 Volkswagen T25. Vee Dub, in its 1980s wisdom, cut a corner during our van’s construction and didn’t fit a 12V socket. So I decided to fit one – a job that is fairly simple: find the source of the electricity you wish to use for the socket, find a home for the socket and then connect point A to point B.
The first thing into the basket was the 12V socket as they only had one type in stock. It is a functional thing with a built-in light and a cheerful green surround. Selecting the wire required a little research, which revealed some wire amp rating recommendations. Coupled with a little knowledge I selected a fuseholder. I also picked up a four-way terminal for the positive battery post to give me an extra space for the new socket on the battery.
Disconnect the battery
First, I disconnected the vehicle battery. If you are fitting the socket to a leisure battery, disconnect that one, too.
I decided to fit the socket into the useless ashtray in the cab. This places it close to the windscreen, which is handy for sat-navs. It also allowed me to avoid the task of trying to cut the metal dashboard.
Prior to cutting or drilling anything, I checked the area underneath to make sure it had clearance for the wiring and I could route the wires through the dashboard without having to remove it. In our ’van, the vehicle battery is under the driver’s seat, which makes things easier, as the cables can be routed under the flooring without having to go through the firewall or any panels.
Battery connections
I decided on a direct connection to the vehicle battery for a few reasons. First, it kept the install simple, and, second, it meant I kept my tinkering away from the rat’s nest that is VW’s wiring loom. It also stops my new addition being the source of problems with other electrical systems.
To start, I laid out the cable from the reel from the install point along the route to the battery terminals and cut it to give me the desired length for all the wires in the circuit. Then I stripped the ends off the cables, slipped some heat shrink tubing over the ends and crimped female spade connectors to connect the wires to the new socket.
With the spade connectors crimped on, I slipped the tubing back over the metal of the spade connectors and shrank it down to tidy up the connections before pushing the spades onto the socket. I did the same for the other end of the negative terminal at the battery end, replacing the spade connector for an eyelet connector and bolting it in place to the battery post terminal.
Always fit a fuse!
With half the circuit in place, I turned to the positive connection to the battery. It is important to wire in a fuse on the positive wire. This needs to be situated as close to the battery terminal as possible. I used a wire capable of carrying up to 17A, but a fuse that will blow at 15A (research suggested this was the best option). I used an inline fuseholder and attached it by crimping spade connectors to the appropriate ends. I dressed the connections with heat shrink tubing to protect the bare metal of the spade connector, but you could also use insulated terminals.
If your soldering skills are fantastic you can add the fuseholder by splicing and soldering the wires together. My soldering skills leave much to be desired, so I find that spade connectors are clean, secure and easy to remove and redo if things go wrong. But remember to cover any exposed metal with heat shrink tubing or electrical tape.
An inexplicable short circuit (especially one that occurs when exposed connections find other exposed connections) is a good way to cost yourself a lot of fuses. The circuit is earthed on the vehicle battery, which is costly in terms of the extra wire but it’s easier than crawling under the dashboard and finding some exposed metal nearby to earth the socket onto.
Testing the circuit
With everything wired together and the battery wires attached to the battery temporarily, I set my multimeter to DC volts and put the probes on the correct wires at the socket points and saw 12V was showing on the multimeter. Success!
I also tested the air around the wiring to check for visible smoke and a smell of burning plastic. There was none, so I moved onto the final phase. To fit the socket into its new home, I drilled a hole in the lid of the ashtray and slotted the socket in. It is quite secure and fits flush with the top. The only downside is the ashtray won’t open again (but we don’t need it).
Now in its new home, I routed the cable back along the cab floor underneath the floormats to the battery. The wires were secured in place with tape during the fitting and the battery wires were connected to the correct terminals. With the cable route planned, the cable is slotted inside protective plastic sheathing to protect it from general chafing and my size 12 clodhoppers.
After only a couple of hours I was all connected up and ready to start charging things, using a sat-nav and boiling a 12V travel kettle. You can apply this same process to add an additional 12V socket to your ’van’s leisure battery almost anywhere, as the principles are pretty much identical.
This feature was originally published in the January 2018 issue of MMM magazine. Want to read more like it? Subscribe to MMM magazine today!
Recent Updates
A class of their own - our guide to A-class motorhomes
Thinking of trading up to an A-class, or even going straight to the top of the motorhome tree? We guide you along the way in this guide to A-class ...
Explore overseas on a motorhome dream tour
Enjoy exotic travel in a campervan or motorhome by hiring, swapping with someone else or exporting your ...
Motorhome water systems: everything you need to know
On-board water is an important part of every motorhome – here’s everything you need to know ...
Campervanning in Europe: what you need to know
Whether you're planning a leisurely drive through the French countryside, navigating bustling city streets in ...
Campervan security: all you need to know
With thefts on the increase, it’s important to know how to keep your campervan secure and prevent campervan ...
Campervan furniture: everything you need to know
Our campervan experts guide you through all the essentials for your campervan, including tables, chairs, ...
Campervan finance: how to fund your purchase
Here we look at the different types of campervan finance available, to help you decide what’s the best option ...
Britain’s best used motorhomes
Want a great motorhome without paying the premium for a new one? Here's a guide to the best you can get in ...
Which motorhome? Choosing the perfect motorhome for you
Choosing a motorhome or campervan is one of the biggest buying decisions you’ll ever make, so it's important ...
Dogs in campervans: all you need to know
Follow our advice and your dog will enjoy campervanning as much as you do ...
Other Articles
Campervan washroom essentials: stay fresh on the road
Our guide will take you through the campervan washroom essentials you'll need so you're well-prepared for your next adventure ...
Electric campervans: all you need to know
Our guide will take you through everything you need to know about electric campervans and what the future ...
Motorhome electrics: a complete guide to your motorhome electrical set-up
Motorhome electrics can dramatically enhance the convenience and comfort of your vehicle – but they can be ...
Lighting for campervans: all you need to know
We guide you through all the lighting options available for you and your campervan, including interior ...
Electric bikes for motorhomes: our ultimate guide
Read our comprehensive guide to electric bikes for motorhome owners, helping you add electric power to your ...
Our guide to 'cheap' motorhomes in 2024
If you're on the hunt for an affordable new motorhome, this is the best place to start – we've rounded up a ...
Campervans in winter: all you need to know
Here's your guide to preparing your campervan for the colder months, whether you will be using it or putting ...
Six alternative campervans to the VW California
Looking for a different option to Volkswagen’s famous Cali? Here are some of the best other campervans out ...
Campervan cooking and kitchenware guide
Top tips for dining like a king in your campervan. This includes the most useful pots and pans, mugs and ...
Buying a campervan: all you need to know
A campervan, with its promise of endless adventures and a nomadic lifestyle, is a dream many enthusiasts ...