[Carl n Susan]

Running the Hondas is indistinguishable from normal shore power to the Montana. You need to check the voltage at the battery. I suspect it is 12.something. If it is the same when you run the Hondas, get into the battery compartment and listen to the left hand 50 amp self resetting circuit breaker. I bet it is the source of the noise. Check the voltage on the Load side when the gennies are running and it should be 13.something. You can jumper the 50 amp CB while waiting for a replacement (hopefully an 80 amp one).