I am always conscience of my 12VDC battery voltages. A fully charged battery bank will read 12.6-7VDC. When I hook up to shore power this reading should jump up to 13.6VDC or whatever mode the smart mode charging source is doing...
What you don't want to see is your battery voltages are always sitting at 13.6VDC all the time when on shore power or generator as this is known to boil out your battery fluids over time. The batteries do well if your smart mode charging source drops back to 13.2VDC when demands are down... Then jump up to 13.6VDC when more demand is required.
This is most likely where your battery acid damage has come from...
I would definitely look at my batteries fluid levels after seeing this...
Roy Ken