wny_pat wrote:
...12 volt deep cycle lead acid batteries should measure 12.6 to 12.8 volts when fully charged with charger not operating! How long it can hold that 12.7 vdc is the question!!
In a nutshell, the above is the simple answer, provided enough time is given to fully charge the batteries (and odd intermittent connection issues don't prevent the batteries from charging fully).
It just doesn't always appear that simple when you end up being the one with the apparently weird symptoms.
Glad the OP got it figured out.