k31th less WHY; more WOT Site Developer 28,302 Member For: 16y 14d Gender: Male Location: Melbourne Posted 02/02/15 06:04 AM Share Posted 02/02/15 06:04 AM I recently pulled my battery out of my car after having it disconnected for ~12 months (slow self-discharge). I made the reasonably smart move of disconnecting the battery from the car electrics itself 12 months ago, otherwise I wouldn't be telling this story, most likely!So I put the battery on my battery charger that only starts on 5V minimum, wouldn't even begin charging... Pulled out the multimeter and checked and it was on a whopping 3.09 Volts... trouble...Bought another battery recovery device that starts at 0.5V and kicked off the charging process with a largely pessimistic outlook.After about 45 minutes it had got the voltage up to about 5.3V but it had stopped there stating the battery had a fault and would not take charge... thought bugger it I'll chuck on the original charger and it started and ran for about 12 hours and got it up to about 11.1 volts and had given up... still not looking good.Connected the new battery recovery charger again and it "tested OK" this time, wow! surprised... beginning to get optimistic here... kept it on charge for almost 4 full days and it sloooooooooooooooooooooooooooooooooooowly recovered voltage. This battery is a SMF/AGM type so it has calcium added to prevent bubbling so it doesn't need replenishing of water reservoirs... in the end it got up to 14.03 volts (while charging).Still could be bad... so the advice online tended to say to leave it for 12-24 hours after you finish charging it and if it still reads above 12.7 volts you've probably got a healthy battery So I left it and it settled down on 12.83 volts I was happy, to say the least Question for you guys... what's the lowest voltage you've ever recovered a battery from? Link to comment Share on other sites More sharing options...
Ralph Wiggum Moar Powar Babeh Lifetime Members 19,323 Member For: 18y 7m Gender: Male Location: Perth Posted 02/02/15 06:10 AM Share Posted 02/02/15 06:10 AM Similar story for me, 3v. It's amazing how well they bounce back if you treat them correctly. Do you have the facility to high rate discharge the battery? This will allow you to punch through the float charge and should help the battery accept close to 100pc capacity after a high amp recharge. (when I say discharge I mean down to the manufacturers specified discharge level.... Not 3v again... ) I also recently dragged a 6v 8ah battery from literally zero volts back to full voltage but I reckon it'll fall over once I demand some current from it. I have a bit of a battery fetish and really enjoy salvaging them. 1 Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,302 Member For: 16y 14d Gender: Male Location: Melbourne Posted 02/02/15 06:15 AM Author Share Posted 02/02/15 06:15 AM Nah, I don't have such facilities... I could take it to an auto-elec or something to confirm...LOL manufactures specs say 11.3 volts is 99% discharged haha.I read a situation on the internet where the poles had literally swapped - the voltage was negative - and the guy STILL recovered it haha. Apparently he applied voltage in reverse to "force it" back to zero (correct the poles) then switched the voltage around correctly from zero and charged it back up! wow Link to comment Share on other sites More sharing options...
Ralph Wiggum Moar Powar Babeh Lifetime Members 19,323 Member For: 18y 7m Gender: Male Location: Perth Posted 02/02/15 06:18 AM Share Posted 02/02/15 06:18 AM my big big charger is a 50am 12/24 unit. Giving the battery a couple of shots of 24v does wonders to push past any sulphation in the plates... 1 Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,302 Member For: 16y 14d Gender: Male Location: Melbourne Posted 02/02/15 06:21 AM Author Share Posted 02/02/15 06:21 AM (edited) On peak output this charger (recovery unit) that I bought does 22v (edit: but only at 0.8 amps hahahah) to "pulse" to fix the sulfation (it must have worked ) , but only does that in "recovery" mode, not in "bulk charge" mode - apparently the most it puts out is 14.3 in "bulk charge" mode, so it almost got there when the battery was at 14.03 voltsKnow any tricks to apply a high discharge to a battery without killing it? Edited 02/02/15 06:22 AM by k31th Link to comment Share on other sites More sharing options...
Ralph Wiggum Moar Powar Babeh Lifetime Members 19,323 Member For: 18y 7m Gender: Male Location: Perth Posted 02/02/15 06:25 AM Share Posted 02/02/15 06:25 AM You car has a high current draw motor with a decent load on it....just saying ......remove the fuel pump relay and crank away. Will be interesting to see how long it cranks for. It'll indicate how well the battery recovered. 1 Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,302 Member For: 16y 14d Gender: Male Location: Melbourne Posted 02/02/15 06:27 AM Author Share Posted 02/02/15 06:27 AM well, other than the car, of course haha!hmmm... I guess I'll put a stopwatch on it to see... any recommendations of results? I'd have no idea how many cranks would be good/bad without guessing Link to comment Share on other sites More sharing options...
freeze_dk I am dissatisfied with my current employment situation Donating Members 8,610 Member For: 17y 6m 27d Gender: Male Posted 02/02/15 06:29 AM Share Posted 02/02/15 06:29 AM My battery went flat once, so I bought a new one 4 Link to comment Share on other sites More sharing options...
Ralph Wiggum Moar Powar Babeh Lifetime Members 19,323 Member For: 18y 7m Gender: Male Location: Perth Posted 02/02/15 06:31 AM Share Posted 02/02/15 06:31 AM Crank it and time it...post results. Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,302 Member For: 16y 14d Gender: Male Location: Melbourne Posted 02/02/15 06:36 AM Author Share Posted 02/02/15 06:36 AM I'm only game enough to do it once and then re-charge the battery haha Link to comment Share on other sites More sharing options...
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