Identical batteries different discarge rate

[Heliblind]

I have 2 kong power 25c 2100ma 11v batteries. I purchased then at the same time. I fly them for 7 min. I'm still learning so basic hover flight. Both of the batteries have been flown the same amount of times. When I fly and recharge I get 25% left in one battery and 37% left in the other. Is this normal for the same batteries to have different discharge rates? There is one thing that is strange. when I plug the battery in that discharges to 25% them motor beeps at a higher sound level. It is what I would call a big difference in sound level. Is one battery beeping louder than the other normal? I have limited experience with LiPo batteries. The 2 seem to give the same amount of power to the heli, but I'm only hovering.

Thanks for any insight anyone can give.
Heliblind

[ChasHeliCop]

The sound is coming from your motor, if it is less audible turn your rotor head counter clockwise and you will hear a louder "beep". Don't know why they are discharging at different rates, could be from different lots, but you wouldn't think there would be that much difference in the cells.

Have you crashed or damaged either of the packs ?

[Heliblind]

I have not damaged the batteries, no crush. I don't want to jinx myself but i have not even crashed yet. I know the beeps come from the motor. Should I be contacting the vendor about the difference in discharge rates.

Heliblind

[ChasHeliCop]

Have you checked the resting voltage right before you fly, to see if one pack may be discharging or not charging fully ? I would probably contact them with that much difference. My packs come in almost exactly the same everytime, of course I run on a timer.

[Heliblind]

I charge the batteries, take them off the cellpro 4s and fly. Both the batteries read 100% done when I take them off to fly. I don't have to go very far to fly, just out in to our backyard. I believe both batteries are fully charged when i fly. I use the DX7 timer, I start it when I take off and stop it when I land. I will see about contacting the vendor today.

Heliblind

[Skiddz]

Might be a cold or cracked solder joint on the battery connector.