RDMueller wrote:
I don't know, all I can say is that my brand new battery was on the Battery Tender for a few months in the garage, properly watered, and 24 hours after removing it from the tender the SG was only 1.225 or so. The voltage was about 12.3v. My guess is that even though the battery is new, it was was somewhat discharged when I got it and the tender is just not an adequate way to fully charge it. Might work fine to maintain a fully charged battery, but don't expect it to ever bring a somewhat discharged battery up to 100%, no matter how long it is connected.
If you have a tossed-off 12V transformer and a meter make up a trickle charger like I mentioned. If the wall wart wiring terminates in a small jack, cut and strip wire, the (+) phase is usually the center of the jack. Plug in and check unloaded voltage. Connect to battery and monitor voltage to your own cut-off point. I chose 14V because at 500 ma and a duration of a few days, I can be pretty well assured that they are charged 100%. Since these batteries are sealed car jars, I haven't bothered with SG. Occasional monitoring shows the batteries are operating as normal.
