8 x T-105 trojans.... OK that is some serious power. I too will express some friendly caution about the venting need if they are flooded acid batteries. It can be done, just research it out . Need fresh air in and an exhaust.
Curious how are you going to recharge 8 of them?
We have had members mount 4, 6 volts across the tongue and 4, 12 volt AGM's. But not 8, yet.
The yellow wire that is cut off is for reverse lights or known as an auxiliary. It comes from the 7 wire plug cable attached to the truck. Since the camper does not have back up lights, it is just dead ended in the box.
The 2, 30 amp fuses,
One is for the camper battery originally on the A frame. It connects the battery to the power converter to protect the wiring etc in case of a short.
The other 30 amp is used in series with the truck charging wire in the 7 wire cable to the truck. This protects the wire and the truck from a short. This is the one mainah was calling TV protection. TV meaning Tow Vehicle.
In this pic of yours I would "guesstimate" the larger red wire to the 30 amp fuse is the power converter fuse and the black to the other 30 amp fuse is the truck charging line. Search and see if that lines up to confrim that is correct. The others smaller wires are for the running/clearance lights, turn signals and the brake lights. The blue wire, assuming you have one blue would be for the trailer brakes. There should be a breakaway switch on the A frame too that comes into that box and ties to the blue brake wire and the hot red battery wire. This power up the brakes in the event the trailer disconnects from the truck
I'm making an assumption you are using some type of inverter with all that battery bank. That is some serious amperage if I'm understanding the 8 trojans right. There is no white DC ground wire in that junction box as it is basically the 7 wire truck cable junction box to the camper DOT lights.
If you look under the camper, starting at the battery, there should be a large white wire off the battery. The red would be DC + and the white DC -. I would get your battery DC minus to that large white wire if you are using your battery setup inside. And yes, if the batteries are inside you need to run a wire out of the camper OR working it inside back to the power converter.
Remember to fuse hot line going to the power converter to not over-amp the small wire of the camper.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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