Most have an in-line fuse close to the battery and two more fuses on the 12V Power Distribution Panel labeled REVERSE POLARITY.
All three of these fuses will blow if the battery is hooked up backwards.
I always look for the word 'NEG' or the symbol '-' stamped on the battery case. Then I make sure this is the battery cable coming from the frame ground.
The RV's can have either BLACK and WHITE cables where BLACK is positive 12VDC and WHITE is frame ground or they may have RED and BLACK cables where RED is positive 12VDC and black is frame ground.
Just to be safe I always look for the stamped on markings.
No harm done just blown fuses. Be sure to correct the battery cables before replacing the fuses otherwise it will just blown them again... That is why the fuses are there haha... That would be a second trip to NAPA to get more fuses...
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"