Unbalanced Battery

[Quadzilla-]

Recently it has come to my attention that I need to monitor my cells voltage indivually. So I checked my first two batteries and both batteries did a pretty good job of balancing the cells while discharging. Staying within a range .01-.02 volts per cell from their neighboring cells. I'm in the process of cycling the batteries 10 times so I'm trying to get the most life from my batteries. Keep in my first battery has 19 charges, finished cycling, and my second has about 6 charges. Finally I tested my newest battery and I notice that it is having a hard time balancing while discharging. I took a screen shot to show you that it ranges per cell .02-.05 volts which may not seem like a big deal but this is a new battery and over time this could be a big problem. I'm not sure what to do since I can't change my charging and balancing process because it is limited to the batteries capability. Notice the difference between the 2nd and 3rd cell below.

 

[N017RW]

Balancing can only be performed during charging.

There is no balance consideration during discharge.

 

[Quadzilla-]

Ok thanks for clearing that up for me. I guess I just expected the third battery to be similar to the other two when it came to discharging. I will have to check the third battery when it is fully charged to see if it balanced then.

 

[silverstoned83]

Ok thanks for clearing that up for me. I guess I just expected the third battery to be similar to the other two when it came to discharging. I will have to check the third battery when it is fully charged to see if it balanced then.

This is simply evidence of the effects of cycling a LiPo. The battery with 19 cycles on it has had enough time to break in and now the cells' internal resistance has began to level out across all four cells. This is important in order for the battery to stay balanced during a full discharge and it also indicates that the battery is healthy.

An unhealthy LiPo will have cell internal resistances that vary more than 10%, the same is also true when it's in the break in process. This difference in internal resistance across the cells will equate to more voltage drop under load