Would you guys recheck your statement that the BLACK WIRE goes to NEGATIVE and the WHITE CABLE goes to POSITIVE.
FOR RV HOOKUPs If the cables are BLACK AND WHITE then the BLACK CABLE GOES to the POSITIVE TERMINAL and the WhITE CABLE goes to the NEGATIVE TERMINAL.
FOR AUTOMOTIVE HOOKUPs If the cable pair is RED AND BLACK then the RED CABLE goes to the POSITIVE TERMINAL and the BLACK CABLE goes to the NEGATIVE TERMINAL..
The absolute best way to determine this is to grab the cable that is connected to the MARKED WORDs on the battery case than says "NEG" or the symbol "-" and this cable should always go to the trailer FRAME GROUND if it is a 12VDC battery on the RV trailer hookups.
Maybe I missed something here about what is being talked about...
Roy Ken