My current trailer has red, black and white factory wiring going into the battery compartment. When I bought it the battery had been removed. I traced the wires back to where they were hooked into other factory wiring. Both the red and black went to positive and the white went to negative. My old camper had black wires for both. Trace the wires to find out where they go. Oh, and as a retired electrician with 40 years experience, I have found electrical engineers to have been wrong on occasion. TRACE THE WIRES TO THEIR SOURCE TO FIND OUT WHERE TO PUT THEM ON THE BATTERY.