I think the poster's 2801 QSF is on a Ford chassis. The BCC operates a little differently from the BCC on a MB. I recall Brian Clemens said MB would not let them connect to their electrical system. On the Ford chassis the BCC connects the coach and chassis 12 volt system when the coach's convertor is charging, when the chassis alternator is charging, and when the battery booster switch is pressed. The BCC will connect the batteries only if there is enough voltage, unless the booster switch is pressed. If the coach batteries are low, it won't connect until the convertor has charged them.
2011 Sunseeker 3100
1997 Pathfinder Toad