My auxiliary Optima battery somehow mysteriously discharged to 5.6 volts after working fine the day before, and after a rainstorm. It is now trickle charging. I need to travel in 2 days and don't want to be stranded. Any idea on what caused this? Can I use an off-shelf replacement as back-up?
hopefully, you left a door/light on. yes you can, but the optima should be ready for your trip. that's one of it's strong points, the ability to deep discharge without much degradation.
Yeah, the Optima Yellow top is an AGM battery that is more tolerant of deep cycle charging, but I would be weary of what caused it to discharge in the first place.
I had a dead battery after leaving an interior light on for two weeks. The fun part was that I recharged it with one of these modern chargers that automatically switches between 6 and 12 volts. When it got the dead battery up to something like 7 volts, it said "done". I guess a fully charged 6 volt battery reads about 7 volts. In order to get past 7 volts, I had to connect it to a 12 volt battery for a while. That was enough to switch back to the 6/12 volt charger and let it go the rest of the way up to 12+ volts. What ever happened to switches?
