Originally Posted by jrambeau
Left it run and generator for a couple of hours. House batteries still dead so put them on charger for a few hours. Don’t seem to take a charge for some reason.
Using the generator to charge dead or almost dead batteries would take many, many, many hours.
By you putting the charger on it that gave you just enough to start it, but as you said, they don't seem to take a deep charge.
Once batteries experience "deadness" they are pretty much done. Doesn't matter if they're not that old or not. Sometimes you can get some life back into them, but usually they will never be healthy, or dependable again. Batteries should never be taken to less than 50%.
As rk911 said...do his steps and then use a hydrometer check the state of charge in each cell. Replace battery if even one cell is bad.
Batteries need to be monitored and maintained often like anything else.