Originally Posted by garbonz
They may be happily charging, but have liked suffered significant damage. I would not depend on them to supply much off grid power, but they may be ok for short trips. Not sure about the refrigerator inverter thing but that may be problematical also without an alternator keeping thing charged up.
Been thru this before myself.... If your batts were that dead, they may be permanently ruined. For your sake, I hope I'm wrong.
I've heard that they could actually become charged with pos/neg terminals reversed.
I had the opposite problem... Batts were being so badly overcharged they are pretty much ruined.