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Posted by D Sherman [72.47.9.228] on Wednesday, July 06, 2011 at 14:15:16 :
In Reply to: Re: batteries posted by Doc Dave [24.245.101.30] on Wednesday, July 06, 2011 at 13:26:19 :
I keep all my unused batteries jumpered together and attached to a small power supply set to 13.8 volts. That's my "float charger". It's always kept them in good shape. Batteries in vehicles are problematic because there isn't usually a convenient place to plug in any sort of charger, at least for me.
My instructions about pushing 5 amps through them for a week was to rehabilitate a sulfated battery that tests "dead" by any modern battery test. The old battery maintenance instructions always said to give a battery a good long charge before assuming it's bad. I've had batteries that were so sulfated that I had to crank the voltage up to 25-30 volts before they would start drawing any current, but after a long careful charge they ended up being good for another couple years. No normal battery charger ("automatic" or "trickle") is going to try to put 25 volts across a 12 volt battery. They'll just sit there with 14-15 volts on it forever, while it draws no current, and you assume the battery is shot.