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Thread: Dead lipo cell.Any ideas how to bring back to life? SAVED!! Reply to Thread
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11-21-2010 11:31 PM
waylander
Re: Dead lipo cell.Any ideas how to bring back to life? SAVED!!
Quote:
Originally Posted by Ken Currell View Post
I believe most people feel that you should never cycle lithium cells but I've done it to more than 200 lithium Ion cells without a problem. Just don't let the voltage drop beyond 3.0 volts or over charge it either.
Quote:
Originally Posted by waylander View Post
It's not a matter of whether cycling lithium cells is good or bad for them, just that it's normally not required and uses up cycles that could be used flying/driving. I personally don't do it myself but there's no harm to it at least.
Quote:
Originally Posted by Ken Currell View Post
No harm if done properly and the three cycles doesn't amount to a hill of beans. To put a potentially compromised pack back into service without at least one or two cycles to assure it can be reliable is risky to say the least.

Good posts. I learned something too.
I think you misunderstood me. I wasn't referring to in this particular case but responding to your comment about never cycling the cells. In this case it would give you a good idea of how well it was saved but I don't believe it would actually help the cell itself. Once you've actually damaged a cell I've rarely seen them come back to full strength. This is assuming that the cell is actually damaged.
11-21-2010 07:40 PM
Ken Currell
Re: Dead lipo cell.Any ideas how to bring back to life? SAVED!!
Quote:
Originally Posted by waylander View Post
It's not a matter of whether cycling lithium cells is good or bad for them, just that it's normally not required and uses up cycles that could be used flying/driving. I personally don't do it myself but there's no harm to it at least.
No harm if done properly and the three cycles doesn't amount to a hill of beans. To put a potentially compromised pack back into service without at least one or two cycles to assure it can be reliable is risky to say the least.

Good posts. I learned something too.
11-21-2010 07:25 PM
waylander
Re: Dead lipo cell.Any ideas how to bring back to life? SAVED!!
It's not a matter of whether cycling lithium cells is good or bad for them, just that it's normally not required and uses up cycles that could be used flying/driving. I personally don't do it myself but there's no harm to it at least.
11-21-2010 04:50 PM
Ken Currell
Re: Dead lipo cell.Any ideas how to bring back to life? SAVED!!
Quote:
Originally Posted by voyager_663rd View Post
Although it's not balancing well, go through the charge/discharge/charge exercise a couple of times. It may still be salvageable. Don't give up yet.
I agree with you. I have done this many times with Lithium Ion cells.

I usually charge the cell at 1 amp, let it rest a bit and then discharge it slowly at .5 or 1 amp to 3.0 volts and record the capacity. Do the identical procedure again and check the capacity again. If the capacity goes higher repeat it again.

NOTE: This doesn't work all the time as sometimes the cell is damaged beyond a successful recovery. I normally do 3 cycles to ensure the cell has a repeatable capacity reading before using it in a pack.

I believe most people feel that you should never cycle lithium cells but I've done it to more than 200 lithium Ion cells without a problem. Just don't let the voltage drop beyond 3.0 volts or over charge it either.
11-21-2010 03:57 PM
voyager_663rd
Re: Dead lipo cell.Any ideas how to bring back to life? SAVED!!
Although it's not balancing well, go through the charge/discharge/charge exercise a couple of times. It may still be salvageable. Don't give up yet.
11-21-2010 03:14 PM
xv-townboy
Re: Dead lipo cell.Any ideas how to bring back to life? SAVED!!
Well your right..The lipo isnt balancing very well.I got excited when it started to take a charge..
To top it off my charger is starting to act up..

Not a good day for batteires and chargers around here..

Thanks for the advice
11-21-2010 01:07 PM
philipa_240sx
Re: Dead lipo cell.Any ideas how to bring back to life?
Quote:
Originally Posted by xv-townboy View Post
Thanks for all the replies and saving my $200 lipo.
Well, it may not be saved for sure. The battery has likely lost a bit of it's punch as waylander suggested.

You might also have some cell imbalance issues that will never be cured. It's quite possible that the one damaged cell will discharge lower than the others the next time you use it... then you'll be back to square one.

I would use this pack very carefully, take it easy on the C rate and use less than the rated capacity. If you don't already own a portable lipo voltage checker, then I strongly urge you to buy one. It's invaluable for checking your lipo's at the field.

I personally use a Hyperion EOS Sentry but even HK has some cheaper ones.

http://www.rcflightstore.com/product...33c769cc222815
11-20-2010 02:54 PM
xv-townboy
Re: Dead lipo cell.Any ideas how to bring back to life?
Saved!!..Tried it with the Nickel metal function..Charged it at 1 amp on the venom pro until the dead cell got up around 3.3..Switched over to lipo balancing and it is working..Thanks for all the replies and saving my $200 lipo.
11-20-2010 11:57 AM
waylander
Re: Dead lipo cell.Any ideas how to bring back to life?
Quote:
Originally Posted by mike88 View Post
No it's the ni-cad you'll want and it only takes a min or two
To be honest it doesn't really matter which you use...
11-20-2010 11:34 AM
Ken Currell
Re: Dead lipo cell.Any ideas how to bring back to life?
Some chargers will charge a pack with a low cell around 2.5 volts. Not sure as to the exact voltage but my Cellpro 10s and probably some other charges will do it too.

If you can charge the dead cell by itself get hold of a Triton charger (the old model previous to the Triton 2 which won't do it.)

Here's what I do with my Triton charger.

Set it on the lithium charging. When you start it charging it will run for a short time and the stop. You can set it at the normal charge rate but it will only charge at the lowest rate. As long as the voltage keeps rising the cell is accepting the charge. You will need to re-start the charger a number of times before the cell reaches the proper voltage. It's a tedious method but it does work if the cell is OK.

Once the dead cell gets over 3 volts at rest switch to a BALANCING TYPE CHARGER and balance charge the entire pack at a slow rate.

Another method might be to tell the charger that there is one less cell and trickle charge it. You can't do a balance charge with this method as the cell count will likely be wrong. BE CAREFUL. Stop and keep checking that the good cells are not over-charged. When the dead cell gets over 3 volts at rest you can stop and do the balance charge as previously stated.

Hope this helps.
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