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Old 12-01-2013, 04:18 PM   #1
loumat
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Default Battery recovery

Lost my plane 4 weeks ago. Found it yesterday. Battery was on all that time of course. Now registers zero volts. Charger just reads low voltage when charge is attempted. Is there any way to restore this battery to use?
Thanks Lou
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Old 12-01-2013, 04:42 PM   #2
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After being left totally flat for weeks the battery is most likely toast. However there is a recovery method that often works on over discharged batteries, but the chances of success diminish the longer the battery was left flat and the more deeply it was discharged.

The trick is to set the charger onto NiCd setting and trickle charge the LiPo at low amps (0.5c or less). Monitor the cell voltages and with luck they should start to quickly rise. When the cells get to about 3.3-3.5v stop charging and switch back to LiPo mode. The charger should now recognise the battery and you can continue the charge as per normal.

Note that you should do the recovery charge in a safe place just in case the battery decides to 'pop' (I've never had it happen but best be cautious). Monitor the battery closely at all times and if any cell does not start to recover or if there is any swelling terminate and dispose of the battery.
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Old 12-01-2013, 04:56 PM   #3
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There is definitely not a high chance of recovering the over-discharged LiPo.

Charge at C/10 MAX (200 ma for a 2000 mah pack) until its up to 3.3 v/cell.

Change to using the LiPo balancing mode as soon as your charger will accept the pack in that mode and charge at 1C to peak it , then cycle the pack normally to test if it recovered.
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Old 12-01-2013, 05:42 PM   #4
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I used to do as above and then one day thought :

With NiCD charging - there's no clever balancing or knowing if one cell is gaining more than another ... you can of course connect a cell Monitor to the balance lead. Basically NiCD charging is a dumb system until it reaches the voltage peak it expects. Obviously we stop it before it gets there ! Posts say 3.3 - 3.5v - but that's per cell ... on a 3S = 9.9 - 10.5V total ... What happens if one cell decides to go down and another decides to go 'hot' - that is too high. You wouldn't know.

So I started to charge individual cells with a modified Futaba servo plug by plugging into the balance lead. I could set an individual cell on the path with NiCD knowing I was looking at the cell when voltage was reported. I could bring it up to the 3.3 - 3.5v and then change to another ... bring them all up to similar level. If one was dead or failed - it showed.

Not saying anything is wrong with other posts ... far from it cause many people do that system. I just wonder if individual as I do now is more safe ?

We still have the possibility though tnat one or more cells is damaged / faulty and balance charge will not work at all.

??

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Old 12-01-2013, 05:45 PM   #5
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That's why i said to monitor cell voltage

Some chargers will do this in NiCd mode, if not plug in one of those cell checkers
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Old 12-01-2013, 05:48 PM   #6
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Originally Posted by JetPlaneFlyer View Post
That's why i said to monitor cell voltage

Some chargers will do this in NiCd mode, if not plug in one of those cell checkers

Yeh ... Sorry - I did note that but was too short in my post ... trying not to be too OTT ...

Back to whether it works ? I have a bunch of LiPos that I've tried both ways on and none have given more than 1 or 2 short flights after .. in fact it's been a wasted effort ... they get relegated to bench use ...

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Old 12-01-2013, 06:28 PM   #7
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Default Good tips

Thanks for the ideas. It is nice outside today and I will take the charger and battery to a safe concrete pad and give it a try. I wont use the battery in a plane until a lot of tests. Better safe than sorry. Thanks again Lou
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Old 12-01-2013, 11:07 PM   #8
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Originally Posted by loumat View Post
Thanks for the ideas. It is nice outside today and I will take the charger and battery to a safe concrete pad and give it a try. I wont use the battery in a plane until a lot of tests. Better safe than sorry. Thanks again Lou
Yeah, best to do this sort of thing on a safe concrete pad. Even those A123's don't do well on this sort of thing. I've brought back four of them, but after shoving current limited to 3 amps into them, they don't recover more than 60% of original capacity. Just not worth it.

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Old 12-02-2013, 03:18 AM   #9
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I have a 6s lipo 5000mah 20c, it was supposedly new. It was reading 2volts total. I tried the nimh charge at .5 amp and it took about an hour to get the volts up to 19.2 total voltage where I stopped and went to storage voltage with balance connector used. Seemed to work and I stopped at 3.7 or 3.8 all cells. Checked a few days later and all but one cell was at storage, #4 cell was under 1 volt. It is now a paperweight.
I got this with a plane I had bought, the seller said he had already gotten one DOA 6s and this was the lipo they replaced it with. Must have been a bad batch. It is not a name brand battery. My friend should have checked the lipo when he received it but it doesn't matter it was a package deal and I'm not complaining. I now check all my lipos when I get them.

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Old 12-02-2013, 03:55 AM   #10
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Originally Posted by bluzjamer View Post
I have a 6s lipo 5000mah 20c, it was supposedly new. It was reading 2volts total. I tried the nimh charge at .5 amp and it took about an hour to get the volts up to 19.2 total voltage where I stopped and went to storage voltage with balance connector used. Seemed to work and I stopped at 3.7 or 3.8 all cells. Checked a few days later and all but one cell was at storage, #4 cell was under 1 volt. It is now a paperweight.
I got this with a plane I had bought, the seller said he had already gotten one DOA 6s and this was the lipo they replaced it with. Must have been a bad batch. It is not a name brand battery. My friend should have checked the lipo when he received it but it doesn't matter it was a package deal and I'm not complaining. I now check all my lipos when I get them.
Another good point

That would be the individual cells "Shelf Life" after charging. Normally that would be many months. Any cell that drops below the remaining cells is reason for caution with that battery.

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Old 02-03-2014, 01:31 AM   #11
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I picked a plane out of a tree after 4 months. Had a 2100 3 cell thunder power. I just finished chargi.g it and pulled 235 watts on my slow stick. Im gonna let it sit over night in an ammo box and see if its fit for flying in the morning.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
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