RV Repair: onan quiet 7.5 diesel, automatic transfer switch, quiet 7

Question
I saw battery voltage low [I do not believe it has a charging system built in gen, ran gen and during the night DC low voltage on batteries caused gen to stop now it over speeds and shuts down unless AC breaker is in off position then it runs fine did some circuit board get ruined ?

Answer
Well Dan this is hard to say with the information you gave me. Exactly what was happening? The generator should have a charging system for the battery that runs it. By saying that the ac breaker needs to be off. Well do you have it plugged in as well. There is usually an automatic transfer switch that might be having trouble. More information for me would be great.