Lipo cell over discharge

[DISAR]

I was running 2 3s lipos in series i.e. 6s1p and when boat reduced speed immediately I brought it out of water, which meant lipo voltage cut-off. When I went home to charge them, the one pack has very low voltage ( abt6 volts) and when I measure the individual cells one cell is 0.5 volts! Do you know any way to recover this cell? Or where to buy a cell to replace it?
My lipos were the Zippy Flightmax 3s1p, 4000mah, 20c.

[Meniscus]

I have a couple of questions:



Did you unplug the batteries when you were done with the run or did you wait until you got home?
Have you tried to balance the cells and charge at .1 amps? When/If you do, please do yourself a favor and do it outside. Monitor closing and watch for swelling. Personally, I were safety glasses. What can I say, I like my eyes too much to let them go. LOL
Any signs of puffing?

[DISAR]

1) I unplugged them when I brought the boat out of water. I never leave them plugged.
2) Tried to charge/balance charge at 0.1Amps but charger does not charge them in lipo mode. So I tried in NiCd mode at 0.1 Amps and charges it until 8.8 volts where it stops. At that point when I measure the cells individually one cell is 0.6 volts.
3) No signs of puffing at all.

Needless to say that I charge them outside and always keep an eye on them.
You have any ideas?

[Meniscus]

Well, I'm glad to hear that you do unplug them after a run. Do you have a separate balancer that you could see if it can bleed power from the other cells? Have you tried that?

[Blackjack-sven]

did you try to force charge just the one cell or the whole pack? If you did the whole pack, try force charging just the one dead cell to 4.0v and then use the lipo charger to continue the rest of the charge.

[Boatman]

My opinion: dispose of the pack or the cell if you are able to. I have never heard of charging lipo cell in nicd mode. I am interested in why you thought to do that. Is that a way of force charging? Really just curious. Thanks

[DISAR]

I charged in Nicd mode as a way of force charging, in lipo mode the charger does not charge it because of "low voltage".

I tried to charge only that cell from the balancing wires but it went until 0.7volts and today shows 0 volts:ThumbsDown01:

That's why I am asking, if there is a way to save the pack or to renew the cell but i cannot find the same one.

[Ub Hauled]

I am w/ Boatman, dispose and get another pack or cell... I personally would NEVER try charging in Nixx mode, different chemicals have different charging characteristics... Blackjack-sven, if you have done it, and got away with it, good for you man,
just please don't tell other people to follow down this road.
Have you ever seen a LiPo explode or burst in flames? I tell you man, Meniscus eyeware would not be sufficient to protect you.

[hide]

If its just one cell you can remove it, you probably have a dead cell.

[DISAR]

Ub hauled

I am not telling anyone to follow this. I am asking if you can help, and if somebody has had a similar case.

[Ub Hauled]

Ub hauled

I am not telling anyone to follow this. I am asking if you can help, and if somebody has had a similar case.

Sorry DISAR:sorry:, I did not mean you, correction has been made...

[Boatman]

that stinks. Wonderful weather out there. hope you have more packs or can get some quick.

[785boats]

Boatman.
Charging an over discharged pack on the Ni Cd setting is an accepted way to bring a packs voltage up to the low level setting in the Lipo mode.
This should only be up to 3.0V not 4.0V though.


DISAR.
I had a pack once that one cell was like yours & after cutting off the heat shrink I found that the balance wire had broken off at the connection on the cell.
You may have the same problem. Also check the pin connection on the balance plug to make sure it is making good contact with the charger plug.
If not, it sounds like a dead cell.
If you can't find an equivalent cell you can remove the dead cell & make it a 2 cell pack. You will need aluminium solder though.
Good luck with it.
Paul.

[Boatman]

Boatman.
Charging an over discharged pack on the Ni Cd setting is an accepted way to bring a packs voltage up to the low level setting in the Lipo mode.
This should only be up to 3.0V not 4.0V though.

DISAR.
I had a pack once that one cell was like yours & after cutting off the heat shrink I found that the balance wire had broken off at the connection on the cell.
You may have the same problem. Also check the pin connection on the balance plug to make sure it is making good contact with the charger plug.
If not, it sounds like a dead cell.
If you can't find an equivalent cell you can remove the dead cell & make it a 2 cell pack. You will need aluminium solder though.
Good luck with it.
Paul.
wow, thanks. That what I was thinking about a wire come loose or is shorted and is pulling juice from that cell.

[DISAR]

Many thanks, will take the heat shrink off and check it.

[785boats]

Ub Hauled.
You must have posted while I was typing my previous post.
I would like to clarify that the pack should be in a lipo sack & that it should take no longer than 5 or 6 minutes at about 0.5A & should be monitored .
I've done it myself with no problems. The flyboys have plenty of info on this.

Boatman
If a wire was shorted there would be bigger problems than a low voltage cell.
sounds more like an open circuit to me.
Cheers.
Paul.

[Meniscus]

Have you ever seen a LiPo explode or burst in flames? I tell you man, Meniscus eyeware would not be sufficient to protect you.

You know....I was just saying don't be silly, if anything happens and you don't even have a shield for your eyes, :flashfire:you lose your eyes. At least with some safety glasses, you have a chance of still having eyes. Your face may be unrecognizable, but you may be able to see.

Also, I'm not as familiar with other chargers out there. I use a MRC Superbrain 977 and I can set for .1 amp and charge those lipos that may not be balanced. Not recommending, but it is a way to very, very slowly bring up the packs during over discharge.

My own personal experience? I had a lipo a little while back that had puffed on me. I decided to toss it rather than to risk health or limb on repairing something that would only cost me a small amount of money to replace. But that's me.

Do I have my own brand of eyewear now? :laugh: Sweeeeeeeeet! :cool2: :thumbup:

[Blackjack-sven]

Boatman.
Charging an over discharged pack on the Ni Cd setting is an accepted way to bring a packs voltage up to the low level setting in the Lipo mode.
This should only be up to 3.0V not 4.0V though.


My bad. I figured that 3.0v was the cells absolute lowest voltage. I know that the nominal cell voltage was 3.7, that's why I suggested the 4.0v setting. And as previously stated, ANY time a lipo is charged it should be in a bag.