Overdischarged Accupower Evolution cells

[etc]

I realized way too late that my C Accupower Evolution cells 4500 mAh were discharged to 0.0V. They sat like that for about a day.

Exactly how much damage done to them? Should I buy new ones?

Good info here:

http://www.candlepowerforums.com/vb/showthread.php?t=185189

 

[VidPro]

depends. i have discharged ni-mh to 0 before and it doesnt hurt it neer as much as reverse charging does. a bit of reverse charge and you can knock 10% off a little cell that cant take it as easily.
1 day no reverse charge, i would bet they are still at 4k, hmm what i would bet though.
HOW they got to zero and weather that included some reverse charge is far more important.

let me test it for you and get back to you in days. in the mean time at least recharge them, if your charger wont get them going, get them going by using something else, then charge them normal like.
and do tell more about what condition this occured in. and what you did to check them after they got that way.

 

[etc]

I recharged them. I have a Voltmeter which says they are at the proper voltage but that's about all, no way to tell mAh capacity.

They got this state by being used in a tape player by an uninformed relative. It was either tape or the radio in it. 6 cells involved, 5 of them at 0.0V and the 6th one at 0.9V.

 

[VidPro]

that many of them showing a 0V state would indicate that the device kept running even after the voltage dropped severly. but a tape radio player might have not been to harsh on them, unless your talking Boom Box running out some major juice.

the huge advantage of the LSD of even the accupower variety is the capacity when charged in similarity would have them getting to the end of capacity in similarity. when they all have a tendancy to go down all at the same time, there is nothing TO reverse charge, because a bunch of them are not HIGH while one is completly discharged.

when they all fall down at neer the same time, the damage from reverse charge is minimal.

 

[Bullzeyebill]

I seldom let people use my batteries. They just do not take care of them. Same with most of my flashlights. Most people have "better" things to do than worry about those little things, such as monitoring cells. I let my wife use my KL5 setup for wandering around the house at night, and make sure I keep it stocked up with a protected LiIon, and periodically check the voltage. For her work at a kids camp in the summers I give here one of my LED lights that can run on three C alkaline's, so no worry about overdischarging there, and spares cells are available for her.

Bill

 

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Yeah, lessons learned here. Others just won't take care of your stuff the way you do. I hope I haven't lost 50 tokens in cells. And they are (were) new cells, only 2-3 cycles on them.

Accupower Evolution are very nice cells with a reaffirming price let's just say. I also have them in D size. They are all they say they are, low self-discharge.

Put 4 of them in 3D Mag with Malkoff 3D and it works fine, of course I haven't checked the runtime. (Not that I have the benchmark to compare to)

 

[etc]

that many of them showing a 0V state would indicate that the device kept running even after the voltage dropped severly. but a tape radio player might have not been to harsh on them, unless your talking Boom Box running out some major juice.
.

It was a 6xC tape player with a SW radio built it... Panasonic I think. Olde thing is broken and won't run off the power cord.

 

[VidPro]

ok here are the results finally. testing a old C accupower i have laying around.
after some 6months of hanging out it had about 2500-3000ma in it still.

i cycled it a few times , and checked the capacity, and it was very high capacity. then i overcharged it till it leaked, then i discharged it completly and then shorted it out for 2 days. after i removed the short it still showed some minor voltage .02v.
after the long time dip into zero land, it had terrible trouble recovering it, but after about 4-5 cycles it is back up to 4067ma on discharge.
things i learned, if using a v-drop charge you gotta go really freaking fast , to insure it terminates like 3amps speed.
after a dip to 0V normal conditioing cycles were very usefull, full charging and discharging to .9v. Weird how that worked might have had some to do with some liquids leaving the battery during the extreeme overcharge.

so other than your reverse charge, which probably occured, test the capacity, then if it is low , run it through some cycles (without destroying it) and it might perk it back up. use it or lose it.