Solar Phone Charger for Camping

When we went camping, we had nowhere to charge our phones and gadgets, so the car batteries ran down. This is my solution!

An old 12v car battery - more on this later

A leisure battery box

A pair of three way battery terminals

Some car accessory sockets (cigarette lighter sockets in old money)

A trickle charge solar panel

Some bits of wire like offcuts from an old wiring loom

A volt meter

The heart of the system is an old car battery. As the USB specification is for 5 volts and a car battery is 12, we used a battery that was no longer good enough to start our car. Mostly car batteries are toast if they drop down to 10v or below or they're unable to generate the power needed to turn over a car. This battery was in that state and has been charging our phones ever since. Anything similar would work, motorbike battery, leisure battery, mobility scooter battery etc.

In hindsight, I would have got an old motorbike battery as this one is a heavy old thing and carrying it out of the car to the tent and back again gets old quite soon.

Time to spend some money. We bought:

1. A leisure battery box or case. This holds the battery and all the stuff and even has space at the end for some wires and bits and pieces. Keeps everything dry and protected.
2. A pair of three way battery terminals. These are as you can see, terminals that bolt onto the battery and have three take-offs that you can attach wires to.
3. Some accessory sockets. In hindsight, I would have shopped around more and found some with a definite click when you plug stuff in. The advantage of using accessory sockets is that once you've driven to your campsite, you should have all your gadget chargers in the car. You can just move your chargers from car to campsite and back again. We also sometimes use a charger that gives 9 USB and a meter from one accessory socket. Now this box is a few years old, it's like plugging your charger into an old car and wiggling it to make sure your phone charges.
4. A volt meter. Yes, you can get nice digital ones that are meant for your car and would've been easier to install, but I wanted it to look like something from a mad scientists lab! Just make sure it can go up to 12v plus a bit and you'll be fine. In hindsight, I should've found some way to angle it a bit more because when it's in the grass it's a bit tricky to see, but you can get a rough idea of how it's doing.
5. A solar panel. These are advertised as trickle chargers. Normal people buy them for their classic cars or their motorhomes. When they lay their vehicle up for winter, they connect this to the battery and stick it on the windscreen to keep the battery topped up. Works perfectly for this job and usually comes with lots of cable and connection options. (We've left ours in the garden over winter and that's why this one looks a bit scabby!)

Now you've bought a nice new leisure battery box, cut some holes in it! We cut two holes in one end and mounted the accessory sockets, and put a hole out the back which we fed the solar panel cable through with a grommet. We also cut a huge hole for the volt meter.

I'm kind of not bad at wiring, but this project is easy. You remember those three way terminals?

1. Goes to the solar panel, should have red and black cables so you get it the right way round. Mine came with ring terminals that just bolted on.
2. Goes to the volt meter, similarly positive to positive, negative to negative.
3. Goes to the accessory sockets.

I will admit that I'm lucky in that I'm always fiddling with cars, so there's an old wiring loom in my garage that gets bit cut out of it. But otherwise a couple of meters each of red and black automotive cable and a few crimp terminals and you'll be done. Just wire each one in turn and it's simple. If you're at all unsure, find that mate who knows wiring and he'll have it done in the time it takes you to make him a coffee.

Take it out of the car, angle the solar panel facing south and grab your in car chargers and you should be good to go.

If you're a bit suspicious of the campsite or will be out all day, tuck it into a tent or in the porch and lean the panel against an outside wall.

We've run this setup for several years now and we've definitely done four or five day camps with no problems at all.