For a few weeks now I have been charing a deep cycle battery using a 80W solar panel on the roof and a charge controller.
The frist few days the battery voltage would settle at 12.8V once the sun went down. Now days it only has a rest charge of 12.6V and I am no longer able to have it settle at 12.8V. Is this common?
I have tried charging the battery on a long and sunny day. The voltage goes above 12.8V easily but at night it settles down to 12.6V and not 12.8V again.
I am worried I am not charging the battery properly. It is often cloudy were I live and the battery is mostly charged quite slowly. I do not have any charging equipement for condition charging the battery using electricity from the wall.