Reviving LiPo's

[Positive Charge]

I recently went to fly out one of my models and found I had not unplugged the 2200 3S LiPo from the last time I used it and it was totaly dead but not puffed up. I was about to ditch it when I remembered something I read a long time ago when LiPo's were expensive. I linked up the pack to a NiCad charger and watched it very carefully until the meter showed 12V, I then took it off charge and put it on my LiPo charger at 1C. It took nearly 2 hours to reach 12.6V.
In testing it is as powerful as identical packs, discharges similar amounts and shows full voltage.
I am not recommending that anyone else tries this but I do expect to be shot at by doubters.

[n3o]

interesting. how long is the flight time??

[JetPlaneFlyer]

When you say it was 'totally dead' do you mean you checked the voltage and it was zero, or simply that the motor didn't run? If it was just that the motor didn't run then that would only show that the battery was below the ESC low voltage cut-off, which would usually be set at a 'Lipo safe' voltage of 3 - 3.1v per cell.

Steve

[Positive Charge]

The moodel is a power assisted glider, I normally have timed 30 min. flights with each of 3 identical packs including the revived one and when recharged there is no significant difference in the Mah put back in to each pack, allowing for the variation in powered flight time, which obviously varies slightly. After about 12 flying sessions there is no difference I can measure between the 3 packs.

[flydiver]

You have a VERY LOW amp draw. What has likely happened is internal damage increases the internal resistance. This may not change capacity but does change performance. Your's is so low you don't notice it.

The bigger problem is that the extreme discharge causes other changes. This 'may' increase the inherent volatility of the lipo. If the risk is worth it to you...have at.
Just be aware, there ARE risks.

Disclaimer - I've done the same thing myself, and have been using the recovered lipo for over a year. It has taken a bit of a hit compared to an identical lipo that was not abused, and is mildly puffed. It is WELL marked and I watch it like a hawk. It is not valuable (like $6) and is ....small (1000mA/2S)... so I figure it's a manageable risk/experiment. This is a deliberate choice and I KNOW there are risks.

[Positive Charge]

The pack was dead, it did not register anything on my balancer and my Lipo charger would not register or acknowledge that anything was connected. There is a label wrapped around the pack marked "SUSPECT" so I can keep an eye on it compared to the other packs I use in this model and this model only. Time will tell.

[Flywhat2]

Hi folks, I know this is an old thd but hope someone out ther will read this and advise me. I have a small 2S LiPo which has been discharged to under 3 V. No puffing or anything. LiPo charger shows fault and won't charge. Tried the NiMh charger trick. Charged to indicated v of about 6 v. Multimeter check says 5.8 V but when connected to ESC, I get no reply from servos or throttle. Connecting to LiPo charger I get error indication.
Anybody got any ideas?
Many Thanks, Fly

[hayofstacks]

A lot of chargers will not acknowledge a battery pack or cell if its below 3v's per cell. You need to charge it to over 6.0v's, and then try to balance charge it from there.

Do you have a li-fe setting on the charger?

[Flywhat2]

Originally Posted by hayofstacks

A lot of chargers will not acknowledge a battery pack or cell if its below 3v's per cell. You need to charge it to over 6.0v's, and then try to balance charge it from there.

Do you have a li-fe setting on the charger?

No, just NiCd and NiMh. I'll try charging to like 6.5 v and try again on LiPo charger. Thanks for info, Fly

[Neko]

I had exactly the same experience. Left a battery in the plane overnight. It read 0 V when I found it. Charged it very slowly up to a reasonable level, and then put it on the regular charging cycle. It puffed ever so slightly (the casing had started out very tight), and I was ready to throw it out. But the guys at Aero Model said give it a couple of cycles of use and see what happens. It's been fine ever since. The slight puff went away and it is has as much oomph as its less abused brethren.