It is wired OK...
just for your info if BLACK and WHITE cable colors are used the BLACK is POSITIVE and the WHITE is NEGATIVE.
If RED and BLACK wires are used then RED is POSITIVE and BLACK is NEGATIVE. What you sometimes see with the battery connections is the mixing of the RV wiring world being mixed up with the AUTOMOTIVE wiring world that you are probably more familiar with like most of us are.
To double check all is correct in your current hookup find the stamped "NEG" or "-" symbol on the battery case and hand trace that battery cable to make sure it is connected to the trailer frame ground connection that is close to the battery regardless what color it is..
Roy and Carolyn
I claim Horse Creek Country in Southern Ill - Momabear is from North Texas
We live in King George VA
RETIRED DOD DOAF DON CONTRACTOR Electronics Tech 42YRS
"We're burning daylight" - John Wayne
2008 STARCRAFT 14RT OFF-ROAD POPUP with PD9260C and three 85AH 12VDC batteries
2010 F150 FX4 5.4 GAS with 3.73 gears - Super Cab - Towing Package - 2KW Honda EU2000i Gen
K9PHT (since 1957) 146.52Mhz
"We always have a PLAN B"