I do a walk around alot with my setup. I like to read the battery terminals when not connected to shore power and like to watch the battery status using a multimeter. A fully charged battery will read 12.6-7VDC.
Then I will turn on shore power and the DC VOLTAGE at the battery terminal should jump to 13.6VDC or higher depending what smart mode the converter/charger is doing.
If I don't see this jump in DC VOLTAGE then this is telling me my connection is not making it from the battery terminals to the charger unit.
I will immediately start looking for the reason...
Another even more simple thing to do is just turn on your ceiling lights when not connected to shore power. They should light up. This will tell you the batteries are connected to 12VDC Power Distribution panel. Both the Battery Terminals and the Charger DC OUTPUT both fed the same point on the 12VDC DISTRIBUTION panel. This allows both the converter/charger when connected to shore power and/or the battery to operate your 12VDC systems.
If you are running LED lights however you may not see them dim with lower 12VDC VOLTAGE like the incandescent automotive ceiling lights will do.
Batteries are very important to my operations and I really am watchful for battery changes. I want to find these battery problems when sitting at home and not when 50 miles back off some forest trail road somewhere...
Roy Ken