i am facing another problem. i have bought a kingmax lipo battery of 11.1v / 1500mah / 20c . i have already an imaxRC B3 charger. i had tried to charge the battery by this charger . but after around 24 hour charging the left and right LEDs of the charger turns red to green , but the middle LED is blinking in red and green. and after detouching from the charger i have seen that the battery is showing 7.4v will u plz help me about this problem?
     

Your one cell has fused/shorted.
If you are experienced enough, you can open the pack and try to check if something can be done.

i am not an experienced person in this field. will u plz suggest any kind of other way?

there is no other way,and this way is actually risky, i'd suggest use tht lipo as 2s and buy a new 3s.

I was given one such LiPo as a freebie by a member here. It's actually a dualsky 1300mAh 3s, but one cell gives no voltage. I use it as a 2s.

It cannot be used as 2s directly as 3 cells are in series. Is your charger ok try charging some other 3s battery. May be your charger not charging one cell. Or as othr suggested one cell may be dead.

You can use a multimeter and some single strength wire to check for a dead cell if your battery has a balance port (see link below).

https://sites.google.com/site/tjinguytech/charging-how-tos/balance-connectors/

Use single strength wire to make headers that can go inside the holes on the balance port. Single strength wire is available on almost all electrical stores. If you still cannot get it, use a cat5e LAN cable (available at every computer store - you only need max 12 inches) and strip it open. You will easily get 8 single strength wires inside, very well insulated. untwist them

You have to be careful you do not short circuit anything. And most importantly be safe.
All the best

i have already tried it and the 3 cells are showing 4.23v, 2.24v and 2,23v respectively. have u any kind of suggestion to check the charger?

Using the balance port, connect the only the 2 dead cells to the output of ur charger.
Charge them in NiMh mode at 0.2 amps for 10-15 mins. Once you see the voltages go up, disconnect and charge normally in the lipo balance mode.

This process usually recovers the dead cells. Use it at your own risk and monitor the cells at all times.

You need to have b5 or accucell 6 or a better computerized charger to do this.