I'll check first for any stray wires like suggested. The Lance receptacle in the truck bed is all molded plastic and you can't see the connections if there is something wrong with it. Before installing though I used my ohm meter and checked each pin together to make sure each pin was infinity with all the other pins and they were.
I guess what I can do is remove 1 wire at a time and let it sit for a few days then see which one quits killing my truck batteries. Then go from there.
All the camper lights are LED and they all work as they should.
My Arctic fox 5th wheel just plugs into my 7 way trailer connection and doesn't have a charging wire to charge the trailer batteries. But that one doesn't drain the truck batteries at all.
I bought a 7way Trailer Y harness for my bumper plug, so that I can put another 7 way in the truck bed for the 5th wheel. That one doesn't have any problems. Then I tapped onto those wires for the lance plug.
There is no battery drain without camper plugged in, and the camper charging wire is not connected.
Also one more note. When I got the camper, there were 2 blown 30amp fuses that are on the output side of the converter causing it not to charge the camper battery.
I replaced them and it seems to be working as it should. So I am not sure why they were blown in the first place.