Re: Battery Charging Problems
I highly suspect your only charging is from your alternator. 13.1v at battery is expected from a 13.7v alternator.
Your shore battery charger is totally inactive. Probably because one of the many fuses is burnt. If it can't sense continuity between a pos. and the neg. terminals on a battery, it shuts down. Thinking its charge may be, or will go, to a ground.
If it is connected to 3 batteries it may have 6 fuses and one going to the charger from the pos. power bar.