I am adding a battery-bank to use with my solar-system to power my needs inside the trailer. The HaulMark trailer came stock with LED interior lighting, that only works when plugged into the truck, and the ignition is in the "ON" position (which keeps all the dash lights and navigation screen on in the truck as well).
I found the junction-box, underneath the trailer, with seven colored wires all connected with those little twist-on wire connectors. Can I tap in here to route different wires to the new battery-bank, assuming I can figure out which wires feed the interior lighting?
I'm concerned with the trailer's frame already being used as the ground for the truck's electrical system (when connected). If I also ground the new battery-bank to the same frame, will I have a problem sharing a ground like that? Would it be wise to also make a connection to allow the truck to charge the solar-battery-bank while driving?
Okay, there are white wires at this junction-box that are supposedly for ground. Can I run a conductor from that to the negative terminal of my solar-battery-bank? (I'm beginning to confuse myself just trying to ask these questions.) Or would sharing the ground between the solar-battery-bank and the truck's battery pose a problem?
Any tips on figuring out which wire powers the interior lights? There's a red wire at the junction-box that is all alone - doesn't seem to be connected to anything, but it's capped off. What could this red wire be for? (I'm asking because the trailer's owner's manual says red is for the "AUX LIGHTING", which seems like it'd be the interior lights.)
Any tips on converting the interior lights to run off the new battery-bank, instead of the truck's electrical system? Thanks in advance for any help.