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Old 10-26-2007, 05:25 AM   #1
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Default Killing cells like there's no tomorrow

Hi guys and gals,

I seem to be killing cells as if that was my job...

First, all the cells I've got here are like a year or so old and haven't been charged for that period. They were stored with a charge though.

What I do is discharge the cell, and then charge it at ~ 3 A... first charge goes fine, but once the cell discharges, its "dead" - my charger charges it, but when I discharge, it only shows like 35 mAH discharged at 5A (0.9V cutoff).

I have had this happen to some Sanyo cells (I had a thread about that waaay back), and so I thought it must have been the cells... but I have a load of Pansan 4200s here (maybe the same as IB 4200), and I've encountered another cell that goes bad... it was in my glo starter (nitro car), and now, when I charge it, it takes like 1000 mAh at 5A, but when I discharge it, it only puts out 35 mAh? Also, it goes from like 1.3 V to 1.8 V straight away at 5A. The temperature also rises steeply, topping at 51 C (I have 47 cutoff)

Is this my charger, or are the batteries bad?

I'm using a MM Cell Master V1.
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Old 10-26-2007, 05:32 AM   #2
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I always use a slow charge on batteries that have been sitting for a while, seems to do the trick...

If all else fail, put the charger on motor mode and pump some straight current into them, that'll wake them up... (not really recommending this though)
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Old 10-26-2007, 08:44 AM   #3
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Try a much lower amp rate to get them back to life, under 1A.

Even then, 1 year is a long time to leave cells unused, I wouldn't guarantee that they will come back to life.
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Old 10-26-2007, 09:22 AM   #4
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I had 8x 6-cell GP3300 packs that I used for 6-months, then left then untouched for 3 1/2 years. I pulled them out, charged and discharged them a few times, all is good - minus about 100mah of capacity. Still good enough for club-racing.

But I agree, I would try a low 1amp charge, or even a 12-hour trickle charge one time to get a solid charge in these batts. After that, discharge them, then re-cycle. If that doesn't resurrect them, they might be dead.
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Old 10-26-2007, 11:09 AM   #5
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I tried 1.5A on another cell, and it seems to work...

I'll try 1.5 on some others too...
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Old 10-26-2007, 11:24 AM   #6
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my method of reviving dead cells is just to shove them in a consumer battery charger (if it does AAA's and C's then it will take sub C's) cycle them a few times, then i put them on a pulse width modulation charger for a few cycles (you can use the discharge function on the battery charger if you have one. if not just use your normal discharger). i did this to some cells in an old drill, and although they had not been left for more than a week the cells themselves were 6 years old. they came back to nearly full capacity. if all else fails then just shove some current through them on a cheapo charger for a few mins.
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Old 10-26-2007, 01:39 PM   #7
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samething happened to my friend , he has a gp3700 that hasnt been charge for 3years , first charge peaked around 300+mah , discharged it at 30amps down to 0.9/cell and equalized it on my novak smart tray , charged it again and peaked around 500+mah , repeated the process again this time a charged it @ 5.0amps instead of 6.0amps , 50 minutes later the pack peaked @ 4549mah
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Old 11-18-2007, 03:19 PM   #8
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Has anyone tried a reverse pulse charge to. Try to revive some older cells I have 2 EP 4200 packs that are peaking at only 3400 MaH
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