some days back i was making a plane out of coro and was checking with the electrics but forget to remove my lipo .so today when checked i find out that lipos are no more working at all and neither it is taking any charge from the 2-3s simple charger that i have so waht i can now do to these lipos to get it back to life.have barely  used it for 5-6 flights only and its 2650mah lipo so its really hurting me like any thing plz do help me to get it back on life.thanks

What is the individual cell voltage of the Lipo now? Looks like they are already in Heaven.

sir the total votage is 3.17 and the individual ones are 3.05,1.75,1.50

Dear SORAV, if the voltage falls below 2.4 V per cell, then the lipo cannot be charged again. It is dead. DO NOT try to recharge that LIPO. It may explode. Only one of the cell is still alive. But opening that pack and removing it would be dangerous and NOT worth the risk. Shit Happens, so dont worry about it. Just relax and invest on another one, and be carefull the next time.

Normally a lipo should not be discharged below 3.7 Volts per cell. at 3.7 Volts a lipo only has 15 % charge left in it which should not be used unless recharged..

Note that on many ESCs, the default cut-off voltage is 3.0v or 3.1v.  So going to that voltage per cell is not a rare occurrence, and they are rechargeable from that point.

There are reports of people getting lucky about bringing such packs to life by "trickle" charging, but there are also other reports where the lipos were permanently damaged.  You can try the trickle charge method if you are truly desperate, and you have access to the charger that support this mode of charging.

Obviously, this may not be the preferred option.

Quote from: anwar on January 26, 2010, 12:26:22 AM
Note that on many ESCs, the default cut-off voltage is 3.0v or 3.1v.  So going to that voltage per cell is not a rare occurrence, and they are rechargeable from that point.

Anwar, the cutoff voltage of 3.1 V is the Onload voltage. When you remove the load the voltage will be much higher. But it is better to stop using the lipo at 3.3 Onload voltage or 3.7 no load voltage to get higher charge-discharge cycles.

If you see, todays market are coming out with lipo buzzers which buzz if voltage is below 3.3 V/cell. The era of using 3.1 V/ cell as cut off is slowly fading.

Quote from: vinay on January 26, 2010, 12:35:13 AM
But it is better to stop using the lipo at 3.3 Onload voltage or 3.7 no load voltage to get higher charge-discharge cycles.

Of course, the best thing is to follow the 80% rule, which is to make sure you always stop flying when you have 20% of the rated mAH of the pack still left.   For a 2000mAH pack, stop flying at around 1600mAH consumption, and this is done my timing your flight.  Following this really helps with the longevity of the pack.

What I was trying to clarify was that people should not shy away from recharging a pack if it is voltage is around 3volts in all cells.  If it is much lower, even then proper/careful use of trickle charging *may* help.