AnAlternateEgo

Hello, i have a 2cell 5000 mah battery that a friend of mine ran completely dead. I've heard that it could be possible to try and save this battery. I'm just looking for a little guidance to get started. I have a venom and an onyx charger. I'm thinking about setting on nimh charge at .01 amps. How long do you think i should let it charge before checking, and should i connect my exterior balancer to the balance lead while charging? Thanks for any and all help you can give me!

vicman

My Feedback: (10)

From what I have read you are dead.
Any attempt at this should be done outside far away from flamables...and video it.[8D]

Flypaper 2

I've saved a few by doing as you say , on nimh. Set to .100 ma and when it reaches just over 3 volts per cell, or 6 volts total for the two cell, then put it on lipo charge. The lipo charger should recognize it when it's over 6 volts. Don't leave it while it's charging on the nimh mode. and pull it off as soon as it's over 3 volts per cell.

GregorB

Here is what I did. Also, if you don't know what you are doing or if none of this makes sense to you...DO NOT TRY THIS.

My lipo 3s 1300mAh battery decided to land with my plane in a tree about 50 feet up. It took me 3 days to get it out of the tree. The battery was swollen and completely dead.

I put the battery in the refrigerator for 2 days until I had the time to fully supervise the recharging attempt. I used the NiCd charging program on my Passport set at 0.1 A. I was able to monitor the voltage as it charged and as soon as it came up to 3.3 volts I stopped. This progressed very quickly. The battery remained cool and there was no evidence of additional swelling.

I checked the voltage after 3 hours and it remained at 3.3 volts. I put it on the LiPo charging program at 1.3 A and 3S. The battery was monitored continuously during the charging cycle. The current increased as a normal battery to 1.3A. The battery remained cool and completed the charge cycle. I monitored the battery closely through the entire cycle. At the completion of the cycle it had replaced 1200 mah.

The battery remained fully charged after one week and has returned to service and is working like no event had occurred.

I am not recommending that you do this...I am reporting what I did with one battery one time.

Rodney

I have saved a few batteries that were discharged to low. One spent the night and following day in a tree. When recovered, all
cells were very low. Charged at a low rate on a NiCad charger untill each cell was above 3.5 volts then put it on the LiPo charger.
I'm still using it to this day (probably about 10 to 15 more flights on it) and it seems to be holding up well. If you try this, monitor each
cell individually while on the constant current charge. You must be sure to not exceed 4.2 volts on any one cell. There is very
little risk in doing it this way. If the cells do not respond then you have to junk them but; nothing ventured, nothing gained.

E-Challenged

I have revived a number of over-discharged lipoly packs as described using the NiMH charger to get each cell up to 3.3 volts around 10 volts with a 3-cell pack. Just don't forget to take pack off NiMh charger and switch to correct Lipoly charge rate and cell count. Best to charge Lipo packs with a balancing charger and monitor what's happening.

fpveric

Again: it not a good idea to do.. but I've done the same thing with good results. It works but fire is a real posability.

danilo-2

My Feedback: (1)

I cleverly left My Lipo battery equipped Tx on for over a week. Needless to say the Battery was Dead.
Finally, about 2 months later.. I tried charging it using the Nicad setting on my Accucell 6. I charged at 3 amps.. for about 2 mins or until the readout said that the voltage (on the one actually dead Cell) was at 3.2 v.
Reset the charger to Balance lipo charge and It accepted the pack. Fully charging it at a 1/2 C rate.
I had previously considered discarding the pack.
But now it's fully balanced and even the IR readings are low and almost identical.