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› "resurrecting " a "dead" lipo battery - a FYI
01-24-2010 07:08 AM  8 years agoPost 1
grantm

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Christcurch New Zeland

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Recently I bought 3 x 2 cell 2200 lipos from HK , and while tow were fine, one seemed faulty and seemed to have a dead cell - one of my lipo chargers would not charge it, as it gave a low voltage warning ...DOA it seemed.
I have read that a Lipo cell is dead if the voltage drops below a certain level - anyway my meter told me one cell was 2.7 volts . I had also read somewhere that someone had resurrected a lipo by trickle charging it under a PB ( lead acid) setting on their charger - and as I have another older Nicad charger that has a PB setting, I got a safety concrete block to charge on, set up and charged the one low voltage cell, using that charger - carefully , and making sure it didnt heat up or anything - well I slowly got the voltage back up to over 3 volts - then got my Lipo charger to work on it again and the battery
seems to balanced and back to normal - so its seems you can "save" those
Lipos ...anyone else found this ?

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01-28-2010 01:18 AM  8 years agoPost 2
ultra2

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Missouri

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good info,
I've got a 3s pack that generates the "low voltage" alarm on my charger, so I clipped the Dean's connector off, and sat the pack aside. My charger has "PB" lead acid charge mode too, I'll have to try that. So you isolated the one low cell by cutting the leads? What charge rate did you use?

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01-28-2010 01:32 AM  8 years agoPost 3
nappyroots2182

rrElite Veteran

Moline, il

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i just used my charger on nicad setting and brought up the voltage of the whole pack to enough volts to be reconized as a 3 cell. then turned it to lipo and balance charged it. the trick is just to bring up the voltage slow and just enough to make the lipo charger know its a lipo

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01-28-2010 09:47 AM  8 years agoPost 4
ultra2

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Missouri

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ok,..
so the low cell doesn't have to be cut out of the pack, and charged individually? I'm wondering now if my charger will see it as 11.1 volts to be charged. Have to try and see!

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01-29-2010 02:00 AM  8 years agoPost 5
ultra2

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Missouri

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I got my Lipo back!
The "PB" charge mode worked like a charm! I charged at .2 A, until it hit 9 volts, then plugged in the balance leads, and balance charged. They were 3.02, 3.12, and 3.24, when first connected, but balanced out perfect! Thanks for the info!

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01-30-2010 02:37 AM  8 years agoPost 6
Justin Stuart (RIP)

rrMaster

Plano, Texas

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Good idea, but is the "dead cell" permanently damaged by going so low in voltage?

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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01-30-2010 04:16 AM  8 years agoPost 7
zaw

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Lebanon, NH - USA

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nahh voltage probably got low just sitting in warehouse and trip to USA, extremely low discharge rate shouldn't hurt anything thing. If you discharge LOW while flying, pack will get very hot and it will likely be dead.

ಠ_ಠ HBK2 built with inexpensive parts! ٩๏̯͡๏)۶ Gaui425

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01-30-2010 04:22 AM  8 years agoPost 8
Hellsiege

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Colorado Springs, CO

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I've done the same thing, set to auto NIMH mode at .1a until my 3 cell dx7 lipo came back up over 9v. Switched to balance and was good to go on my BC6. I'm sitll on the first cycle, but so far it's working good. Glad to see yours worked out too!

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01-30-2010 02:03 PM  8 years agoPost 9
ultra2

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Missouri

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my guess
is that my charger must have a threshold voltage, and if the pack is below that it won't initiate a charge. I'll be curious to see how well it cycles out with flights, ..fingers crossed!

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01-30-2010 03:57 PM  8 years agoPost 10
rexxigpilot

rrProfessor

Florida

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nahh voltage probably got low just sitting in warehouse and trip to USA, extremely low discharge rate shouldn't hurt anything thing.
Depends on how low the voltage goes. 2.7V on the one cell is not likley to cause a problem. It is my understanding that permanent changes to the chemistry will occur in a lipo that is allowed to discharge to a very low voltage (don't know what the threshold voltage is unfortunately).

I have "recovered" both lipos and A123 packs with cells less than 1.0V using the NiXX/Pb charge method. They did not work properly after that. The lipos lost the ability to deliver sustained high discharge current. The previously low cells puffed. A previously low cell in an A123 pack exploded the case while recharging at 1C.

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02-01-2010 07:53 PM  8 years agoPost 11
grantm

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Christcurch New Zeland

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to Ultra 2
sorry, hadn't looked at you question until now - yes I did single out the one low cell, and charged it at about 60mah from memory...and at 6V on the PB setting. But as someone else points out , the NIMH setting also works. The charger, as has been suggested, has a cut off point for recognising low voltage, and I am sure I can get into the program and change it ...will do just that as I have often seen a low voltae warning so its probably set too high.

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02-05-2010 07:53 PM  8 years agoPost 12
Stolla

rrKey Veteran

Port elizabeth South Africa

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I charge it through the balance lead, just measure which one is bad and charge it as a lipo 1 cell

Common sense may not be common after all

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11-16-2011 01:49 AM  6 years agoPost 13
Reki

rrNovice

Chugiak, Alaska - USA

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You guys are the bomb!! I was soo depressed after I bought what was thought after I received it to be a dead used $100.00 lipo off ebay with no return, and fallowing your steps its completely alive agains and balanced!!!

Thanks soo much!!

Reki

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