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Battery CPR


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So over the last 3 months i've been trying to revive a battery, yes it seems futile and pointless but its a fun experiment for me. the thing wasn't dead it showed low 12v when disconnected, but it cant supply current. i started by giving it a "reconditioning charge" with a bluepower IP22 charger, then i put a 30W panel on it for about a month. then i drilled some holes and filled it with electrolyte stolen from other batteries of the same type. Then put it back on the 30W panel again for another 2 months. all the while i didn't try to discharge it once. See i figured that a slow long charge may help to rebuild the anodes and cathodes or whatever. something which is true for nimh and nicd batteries. but it apparently didnt do much.

Last night i gave it its first proper discharge, putting about 80W on it only gave me 30mins and the voltage dropped to 10.3 so i figured there is obviously an imbalance in the cells and thought it would be a good idea to drain it and recharge so they all have equal charge. i put a small 15W DC load on it and this morning the thing sat at 8V. So then i put a 1A charger on it and watched the voltage rise. i did this so that i could get an idea of what the internal resistances of the cells where like. The voltage quickly climbed to 10.6 then very slowly to 11, this tells me one of the cells has very high internal resistance and isnt taking a charge. charging it up like this wont help. 

It probably has lots of sulfation and that has to be removed with higher voltage, or rather, the best chance you have is with higher voltage. I dont have anything that goes higher at more amps that i can control manually.. but i do have a DC stick welder. so popped that on and gave it 45A, the voltage started out in the 30's. so after a few minuites its dropped to 20 and then about an hours worth of off and on 45A charging has the charging voltage at 16.5 at the same 45A. 

now since the welder is being current limited i assume the internal resistance of the battery has indeed dropped. and it is better balanced than before. so what i will do now is connect up the IP22 again and have it go through a recondition charge again to top it off. 

then if thats done we can do another load test. fingers crossed :D


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Ok so its been acting super weird under charging. i haven't monitored it like this before during charging but now i noted that it starts fine in bulk it ate up the charge, then in absorb the problems started. charge current fluctuated between 10A and 20A at the same voltage, which is what absorb should do but the current should steadily drop not bounce around low then high. It then suddenly went into float, eeh ok.... Then while in float, the charge current again went above 10A. By the way the charger can be used as a power-supply so that's why it didn't go back into absorb.

Now the battery was quite warm to the touch, i checked and Yeaah its not lekke. Wait a minute...

All of a sudden i realise this is one of the batteries i marked as being unrecoverable, I am pretty sure i remember that hotspot in that same place from the last pics i took, Doh. its a short or very close to it and its draining that cell for sure and i don't think there's anything that can be done. All the other ones i had which i marked as being OKi have given away already. Oh well, it was fun playing with it again, i had so much hope after 3 months. 

anyone have an idea maybe? more volts and amps could burn out the spot? is it maybe just sulfation, i'm not quite sure really.  




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On 7/29/2016 at 8:48 PM, Weasel said:

 i've lost many a shirt

+ 1. Mine from carrying them. Wife has given me my last ultimatum before the culling starts. Too weed out the dumb ones, I think she thinks. :D

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Declared deceased 10:40 last night. autopsy was this morning. 

@Chris Hobson was indeed right there was some sediment at the bottom, could very well have been the cause of the hotspot. other than that i didnt really see evidence of sulfation but it could have been that my desulfating welder charge did the trick in getting rid of any there may have been. it also possibly explains that the final blow could have been the high charge current causing excessive sediment to form? the other problem and i think the main problem is that the Anodes where so brittle and broken and even though I very carefully opened it i couldn't remove one that was not completely in pieces, its not a carbon electrode its just that brittle.




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