RR
I think we are both on the same page now.
Just one thing.
The towing switch is a selected function, not automatic.
Depending on Main Batt charge state, there may only be enough power for a half hour tow.
Likewise, refuelling on batt, there is only enough power for approx 15 mins. The logic being that 15 mins is enough time to get enough fuel in to the left main fuel tank to start the APU.
Quote:
The Main Bat again will only be supplying if main DC is not supplying.
I.e. when there is no DC (lower than a given value) in the BUS. I.e. when nothing (from AC source) is feeding DC bus. In this condition MAIN battery supplies (automatically) required energy to the bus through the BDM. (if batt. switch is ON)
Just to be clear, the BDM sits beteen the battery and the hot batt bus. The hot bat bus is isolated from the main DC bus unless DC bus power is lost.
