Pick up a DC MULITMETER. Measure across the battery terminals and it will read 12.6-7VDC if the battery is fully charged.
Then fire up your shore power thing and your DC VOLTAGE across the battery terminals should now read 13.6VDC.
If it does read 13.6VDC coming from your on-board converter/charger unit then operate the BATTERY DISCONNECT switch. Now your DC VOLTAGE will drop back to the 12.6-7 VDC telling you your battery is totally disconnected from your on-board converter/charger unit.
Everyones situation is different so read it for yourself... My battery disconnect totally disconnects all the batteries from the trailer system with the exception of the slide-out and tongue jack relays which is attached directly to the battery terminals.
Roy and Carolyn
I claim Horse Creek Country in Southern Ill - Momabear is from North Texas
We live in King George VA
RETIRED DOD DOAF DON CONTRACTOR Electronics Tech 42YRS
"We're burning daylight" - John Wayne
2008 STARCRAFT 14RT OFF-ROAD POPUP with PD9260C and three 85AH 12VDC batteries
2010 F150 FX4 5.4 GAS with 3.73 gears - Super Cab - Towing Package - 2KW Honda EU2000i Gen
K9PHT (since 1957) 146.52Mhz
"We always have a PLAN B"