geoffbeaumont Posted May 18, 2023 Share Posted May 18, 2023 Technically off topic, given the battery came out of our caravan and was heading for the greenhouse... I've got a retired 105Ah leisure battery which failed a drop test last year but was at the time still working perfectly well for light loads (it was tested because we were having problems with the caravan mover - though I've discovered this week after fitting a new battery that we had a dodgy connection, and we were lucky it was problems moving the van not a Top Gear style caravan inferno). The plan was to use it to power a heat sink/ventilation fan in the greenhouse, topped up from a small solar panel - just a 12V bilge ventilation fan, so low but continuous load which it would probably have been ideal for. However, someone (probably me) left the master switch on in the van over the winter, and the voltage of the battery has dropped to about 5.5V. Smart charger doesn't want to know, although it's supposed to be able to work with a battery that's down under a volt, so I've tried sticking on on my old dumb charger for a while, but not much to show after a couple of days. I'm guessing there's not much I can do to recover it from here? I know it's never going to be a "good" battery again, but just capable of charging to 12V or so would likely be good enough. Quote Link to comment Share on other sites More sharing options...
hurbie Posted May 18, 2023 Share Posted May 18, 2023 you could try connecting a 12 volt source (extra battery) to the dead battery , and then hook up your smart charger , normally they start charging . you can then remove the extra 12 volt , and let it charge the dead battery . on my work battery's that had gone down to 12.1 volt are considerd "dead/broken" and don't get warranty ... Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted May 18, 2023 Author Share Posted May 18, 2023 Haven't got a spare battery that I'd risk, but I do have a lab power pack...wonder if that would do the job. Worth a try! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 18, 2023 Share Posted May 18, 2023 Worth saying if the dead battery has a short in it (quite possible) then sticking another one in parallel could well knacker it/be dangerous/explosion..... I'd cut my losses and get a small off the shelf 12V 7Ah battery and know it is likely OK. 1 Quote Link to comment Share on other sites More sharing options...
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