My MH has VDO gauge, it is reading just a little over 11 volt while running , today i started my coach and the battery read 11.7 volts, once i started the engine it dropped to 11.4 , i started the gen...
While a jumper wire between battery positive post will work electrically, it is QUITE DANGEROUS.
If either end jumps/vibrates off while driving, you will have a dead short to ground (any metal) with full battery amperage applied. Welding and fires can happen.
Safer to hard wire a jumper or combine wires on the battery combine solenoid as I outlined above.