Quote from: VC on January 15, 2015, 08:37:17 PM
Charge it for 30 mins and the voltage reads @ 0.8V for the damaged cell and 8.45 for the pack. Switch off the charger it goes back to 0.1V and 7.70V respectively.

Regret to say VC ji, your Lipo might be beyond recovery. this phenomenon is exhibited only when its damaged too much.
normally with a 5V charger, the cell would spring back to at least 3V and will stay there for a couple of minutes so that we can shift it to normal lipo charger and continue charging to 1C.
and this being a TX lipo is risky to go down suddenly switching your TX off.

Ashok.P

v2 eagle - Perhaps, you are sadly right. I notice that my electronics engineer (Sandy) is on board at the moment. Let me tickle him.

Just being curious, are you connecting the Nokia charger to the battery or to the damaged cell?

Yes I know I'm an idiot and many will call me mad. But in the pursuit of personal knowledge I stripped a puffy 3 pack of it's outer coverings and with a hypodermic syringe stuck each cell and allowed the gas to escape. I used one hand to apply sufficient pressure on the cell to expel the gas and the other hand to hold a piece of adhesive tape with which to seal the cells as soon as the cell was it's usual skinny self. I did this to the 3 cells and then liberally covered them with wing tape and replaced the outer cover. That battery is now used on my workbench and is used for setting up quadcopters and planes, testing motors and many other small jobs. The battery is about 4 years old and it's been "fixed" for two of those years. One cell is slightly down compared to the other two but still delivers the power needed.

I have since repeated the operation on a number of other cells and they are used when setting up multicopters outdoors and never any more than in hover mode, 2 feet off the ground. I've never been one to take silly chances, some may think this was a silly chance, but it works and more importantly it's saved me money. I'm not a believer in throwing which works or can be modified to do something other than it's original task. None of my doctoring has rewarded me with a repeat puffer and only one battery has had to be scrapped (apart from connectors) as it had one cell which refused to play ball. From new it was a little iffy anyway.

Just one point with buying batteries. May I suggest people be wary of Mega sales, Sales of the Year etc. etc. etc. with some well known companies. I know for a fact they are a front for disposing of older batteries. We all know batteries have a certain shelf date and for any company selling batteries, to be caught with those with a Use By Date about to expire, it means lost dollars. What better way to dispose of them by getting people to pay more for them than their original cost. I've seen some hobbyists go mad at some sales and buy up big on batteries which were selling for around 20% off. It was some time after those sales that batteries seemed to dying somewhat prematurely. They still worked and mostly still charged OK, but the loss was more than just 20%, sometimes as much as 40 to 50%. Anyone who's been with one company in particular may have noticed one type of battery which has been in every sale and in every clear out offers. It's a very long battery which was once pushed as suitable for modification to build your own, something I'd never recommend. I do suggest these are avoided because I couldn't imagine any warehouse manager repeat buying on an item which doesn't sell.

As I said, this does happen and the general manager of a Chinese Hobby outlet told me it's common practice. To be honest it a logical thing to do, but I can't help but think it's a little underhanded. Then again, I';m funny like that :-)   Stu

Has anyone tried this? Seems incredible. What do the pundits say? Can I connect a fully charged Turnigy 2200 mAh aircraft battery to my, one cell discharged to 0V and reading at 7.8V, Tx 2650 battery and revive it?

This may help
http://flitetest.com/articles/Parallel_Charging_Your_LiPo_Batteries

Edit: unsolicited response from a non pundit!

@VC Sir, please check the dead cell is internally short or not, else the good lipo also will be damaged.

Edit: also the working cells should be damaged due to over current charging if the dead cell is internally short.(just think charging a 2s lipo charging with more than 40 apms current)

@akhilzid - How do I do that?

Please remember that you are about to advise an illiterate idiot who is probably older than your Dad. So keep your advice simple and idiot proof.

FYI when I tested it with a multimeter, each individual cell beeped.

dont need to test the other cells and the connection i mentioned below is only for dead cell.

first confirm that the cell voltage below 1 volt

if yes,
use continuity tester(or with multimeter with continuity tester mode)

Quote from: VC on January 18, 2015, 11:03:51 PM
FYI when I tested it with a multimeter, each individual cell beeped.

check by swapping connection(means if you tested with positive multimeter with positive battery lead then check also with positive multimeter with negative battery lead)

I checked that too. With the multimeter leads reversed, it does not work/beep. Now what?

Cell voltage is probably zero on the damaged cell.

that means the cell is not internally short, and good to go charging,

but i still recommend try charging with any smart chargers(like imax B6) in NIMH/NICD mode to recover battery to be safe side.

I have a Greatplanes Triton charger and it refuses to charge the battery on NiMh / NiCad Mode.

try charging just the cell only, not the whole battery.

Ok. Will try that too.

I had a similar problem due to leaving a Lipo in my transmitter which I forgot to switch off. The battery was discharged well below 3 volts per cell (I can't recall the exact voltage) I used the NImH charge at a very low input (100mw) and it recovered all cells. I do recall it refused to take the charge initially but as soon as I dropped the amps setting to 100mw (.1) it managed to keep charging. I waited until each cell was showing over 3.4volts and then quickly changed the charger to standard Lipo settings and away it went. One battery restored.

I keep a record of all my batteries with purchase dates and anything which could affect it's use such as being dropped, degassed or restored. I take notes on a battery if it displays a particular cell as low volts. The battery I restored did show a small loss in it's fully charged voltage. Point 4 of a volt I can live with.

Should any battery suffer being dropped or over discharged I use them either on my workbench, setting up or in one of my boats.

Vc ji, do you run er 9x in your tx?