12V Battery Box
I have a 35AH Gel battery in a box in the back of my truck that is charged by the solar panel on the roof (see my other instructable). It's in a Plano Marine box which can be removed and taken into my tent when camping. I use it to charge my phone and bluetooth speaker or run the 12V fan in the back of the truck when not driving.
Wiring
I've installed this charging socket along with a voltmeter and a small switch. I've drawn out how it is wired. It's easy to cut through the plastic toolbox, just carefully score over your line several times with a knife.
I build a tiny wooden platform that slips over the battery and the charge controller is screwed down onto.
Finished
I've cut a small viewing hole through the top and just taped it with clear packing tape so I can view the lights on the charge controller, because I've had issues with the connection to the solar panel wiggling loose and then not charging the battery.
I haven't wired the Ammeter up because I don't have a shunt. Might do that in the future.