Converter?

[MTHook]

2015 Windsport 34E
I know a converter changes 120 volt AC to 12 volt DC.
I had dead batteries yesterday both coach and the chassis were dead( less than 7 volts). I put the chassis battery on charger. Managed to start the engine. On charger it has 13.8 volts. The coach has 13.8. Engine and charger off and shore power off the chassis has 12.8, coach 12.6volts.
Engine off and shore power on coach has 12.6. Shouldn't the coach be higher if the converter is charging the batteries?
This has happened a couple times, always after the shore power was off for a day or so, with nothing on except the normal monitor systems being on.

[Ejohn2317]

Anytime you battery drops below 12v you damaging the battery. If this is the original battery it is over 5 years old and probably lead acid. Even when you sit in storage your batteries drain. You could check the water in the sells, but more than likely you will need new batteries. Most RV manufacturers install a cheap battery charger. They put out a constant 13.v even when the batteries are charged this is not good for your batteries. I would suggest you look into a 3 stage Progressive Dynamics smart charger that is an easy swap with you current charger. Your new batteries will charge faster and last longer.