Strange behaviour from my battery.

[Rufus]

Cell number 2 is 75 mV higher than the other 2 when the battery is fully charged. When it has dropped down to about 88% they are all equal and then number 2 starts speeding up discharging and when the battery has reached 50% it is 200 mV lower then the other cells and the total voltage is around 11150 mV.
I know my battery is rusted but is that normal that the bad cell get higher voltage when you charge the battery?
From 40 % (when the voltage goes beneath 11100 mV) it only takes 1 minute to drop down to 10 % and the P2 is only connected to my Imac, nothing else is on.
If I go flying with my P2 with fully charged battery, it takes 3-4 minutes before I have to land it.

 

[N017RW]

Cell number 2 is 75 mV higher than the other 2 when the battery is fully charged. When it has dropped down to about 88% they are all equal and then number 2 starts speeding up discharging and when the battery has reached 50% it is 200 mV lower then the other cells and the total voltage is around 11150 mV.
I know my battery is rusted but is that normal that the bad cell get higher voltage when you charge the battery?
From 40 % (when the voltage goes beneath 11100 mV) it only takes 1 minute to drop down to 10 % and the P2 is only connected to my Imac, nothing else is on.
If I go flying with my P2 with fully charged battery, it takes 3-4 minutes before I have to land it.

Any number of cells in series will exhibit different charge/discharge rates which is why LiPos are balanced charged to help maintain peak performance. Because yours will not balance it is exhibiting signs of typical aging.

Time to retire it.

How many cycles BTW?

 

[Rufus]

Any number of cells in series will exhibit different charge/discharge rates which is why LiPos are balanced charged to help maintain peak performance. Because yours will not balance it is exhibiting signs of typical aging.

Time to retire it.

How many cycles BTW?

44 Cycles, 86 % of life and 4460 mAh at full charge. Probably not taken good care of . Left it fully charged for 2 months last autumn.

 

[N017RW]

44 Cycles, 86 % of life and 4460 mAh at full charge. Probably not taken good care of . Left it fully charged for 2 months last autumn.

Well that is a know killer but even so many are complaining of dramatic drop-off in performance near the 50 cycle point.

 

[Rufus]

Well that is a know killer but even so many are complaining of dramatic drop-off in performance near the 50 cycle point.

That happened for me too last week. Luckily we still have a lot of snow here around the arctic circle in Sweden so the first landing went rather smooth. Next day I took it up again and now I had it insight all the time and after just a few minutes it started to descend and I gave it full pitch and managed to get it back before it was lack of power. Now I have ordered a new battery and will take much better care of this one.