I've been using 11.1 Volts, 4200mah, 20C, 3S Li-Po battery for quadcopter. I've charged the battery twice and it is 6 months old. Recently it's discharging too quickly. I hovered it for hardly 1 minute and the voltage dropped to 6.5Volts. Previously, It stayed alive for nearly 7 minutes. Will there be a possible leakage of current since we refabricated the electrical components?

@mk94 sir,
6.5v on 3s???
Hope you have a cell checker. And an intelligent charger.
I fear at least one cell is dead!
Pl check voltage of each cell before proceeding further.
Is it getting bloated?
Regards.

One should never let voltage on any of the cells of a LiPo Pack (or any Lithium chemistry battery) go below 3 volts or else that cell becomes permanently damaged.
Get a LiPo Alarm set it at 3.8 volts and then get a new LiPo and you will never damage a LiPo again.

I hope u put it in storage mode while not using more than a few days .

@K K Iyer,
You were right. One of the cells was dead. Thank you

@IndianHobbyShop,
Thankyou! It was a valuable information