[rohrmann]

The symptoms you are describing are very likely caused by having your battery disconnect switch OFF. Your CONVERTER, not your INVERTER is what charges your batteries and provides 12 volt DC power. If the batteries are dead, and the disconnect switch is OFF or open, no power gets to the batteries and none comes from the batteries when not connected to shore power. When you are connected to shore power with the disconnect switch OFF, you will see power to the 12 volt system, but that is coming directly from the converter. Turn your disconnect switch to the ON position. Hopefully your batteries are not damaged from being discharged. Your INVERTER uses 12 volt DC to make 120 volts AC, and that is what would be powering your fridge when not on shore power, but dead batteries will not work and when not on shore power your fridge will not work. Your water pump and most interior lights work off of 12 volts DC.