In researching adding more solar I discovered that unless charging , batteries should read no more than 12.7 Max (full) and should not be allowed to go below 12.1 ( 1/2 discharged ) so your numbers looked ok? Or way low with the bad gauge?
Off topic somewhat, As far as the refrigerator running on inverter comment I'm confused , Mine (2003) is not set up to run on the inverter,nor is the electric heater (aqua hot) there are two plug in wall plates behind the fridg, one inverter powered, one not . The ice maker is plugged into the inverter controlled socket and the refrigerator the non inverter .. generator/shore power only wall socket. unless its been changed I think thats the way it was meant to be used. I was told A gas electric refrigerator uses more energy than a home residential when on electric due to the high wattage heating element. vs a 4-500 watt compressor.
This does remind me however I need to clean up those terminals !