There is a 35AH gel battery in a box behind my truck that is charged by the solar panel on the roof (
See my other instructions).
It's in a piano ocean box that can be removed and put into my tent while camping.
I use it to charge my phone and Bluetooth speakers or run a 12 v fan behind the truck while not driving.
I have installed this charging socket with a voltmeter and a small switch.
I have drawn the wiring of it.
It's easy to go through the plastic toolbox, just use the knife to carefully score a few times on your line.
I built a small wooden platform that slides through the battery and the charging controller is screwed to it.
I dug a small observation hole at the top and pasted it with transparent packing tape so I could see the lights on the charging controller, because I had a problem with the connection to the solar panel, it would loose and then not charge the battery.
I didn't wire the ammeter because I didn't have a splitter.
This may be done in the future.