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Lipo question...

Old 10-19-2006, 08:58 PM
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SS2P
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Default Lipo question...

I 've had left two lipos in my typhoon already- by accident and it has sucked both of them down to around 2 volts. I know that it is probably hard to recycle but I just tought that maybe it is possible with a good charger.. would be nice to save 120 bucks
Old 10-19-2006, 10:17 PM
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Default RE: Lipo question...

I think it is Hall Woo at RCGroups who has resurrected some lipos by slow charging them. I don't remember the exact charge rate, but I recall it was very low, maybe a 1/20C rate?

Monitor packs carefully while they are charging! I am also uncertain whether a resurrected cell has any other damage that you may want to be concerned about.

This is an excerpt I found from one of his posts:

>Astrobob was able to restore his 3S1P pack by charging at 50 ma for 3 hours
>Apparently a slow trickle charge is like chicken soup to a sick battery contrary to >www.batteryuniversity not to trickle charge.
>
>Normal looking and non-smelling LIPO cells can only be restored.
>
>LEAKY AND SLIGHTLY DAMAGED LIPO CELLS SHOULD BE DISPOSED, THEY CANNOT AND >SHOULD NOT BE RECHARGED SLOW OR FAST.
Old 10-19-2006, 11:09 PM
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Default RE: Lipo question...

You can try and trickle charge them at a 10% rate until they get upto 3.2 volts per cell, if they do get up there. So if they are 2100mah packs, the normal charge rate is 2.1 amps, try and trickle charge them around 200ma or .21 amps until they recover to 3.2 or 3.3 volts. Then you can up the charge rate. That is your only chance.
Old 10-19-2006, 11:22 PM
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Default RE: Lipo question...

ok thanks... I'll try it... I have one 1320 TP pack and one 2100 impulse pack..

I hope I will have good luck..
Old 10-19-2006, 11:50 PM
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Default RE: Lipo question...

So .13 amps and .2 amps and just monitor them and see what happens.
Old 10-20-2006, 08:08 AM
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saitofreak
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Default RE: Lipo question...

If the battery pack was flat for only a few hours, at most a few days, then the above advice is fine. However, if the packs are kept flat for weeks or months, then toss them in the bin. When over-discharged(flat), re-chargeable lithium cells form microscopic conductive "tendrils" or "fingers" that breaches the electrolytic barrier between the electrodes. This results in higher self-discharge and reduced cell capacity - and in the worst case scenario causes internal shorting and possible fire/explosion - typically under charge and with no warning.
If you accidentily flatten a lipo, then perform recovery immediately.
Old 03-26-2012, 06:08 PM
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Default RE: Lipo question...

My story-
HZ Super cub Lipo flying great, but it gets dark-i lose it in tree. Way up in tree.
After several wind storms, rain storms, and weeks, I get it back down from tree, of course, with a dead battery.
MONTHS later ( Sept. to March) I attempt a recovery: you can look around for a wiring diagram, Cell # 3 is zero volts, battery measures 4.7 volts.
I charge # 3 cell with 10 volts for about 30 minutes, it comes back to 3 + volts, then charge on the balancing charger, and it reads 11.2 volts just like it should. Seems to work fine, I have yet to fly it, but it seems fine.
Old 03-27-2012, 09:27 PM
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Default RE: Lipo question...

Just as a note, LIPo batteries shouldmeasure 4.2 volts per cell when fully charged. If you have a 3 cell that reads 11.2 volts, then it is discharged. 12.6 volts would be correct for a fully charged 3S battery. I don't recommend using that battery.

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