Tool/software:
Hi,
I'm using a BQ40Z80 with external balancing on a 6S, 5AH pack. Balancing circuit is as follows in the image below (note, the 51R resistors have now been replaced with 18R to try to increase balancing rate)
I have noticed that cell balancing does not always occur, even when a large imbalance exists. To test this, I charged a single cell (cell 6) in the 6S pack slightly more than other cells. The BMS reflects this in the calculated balance time:
However, at times the balancing stops (CB is cleared), even while the voltage of a single cell is clearly still higher than all other cells:
Particularly frustrating is that often when recharging a pack, balancing won't be active during the charge. Our charge rate is high (over 1C), so I'd prefer if balancing always occurred during charging, to help avoid a COV terminating the charge, as opposed to natural current taper.
Here's my balancing configuration. If you need any further info please let me know:
What determines whether balancing should occur? I would have though that so long as Cell x balance time >0, and the BMS were active, balancing would remain active? What would cause it to stop balancing, particular while the pack is on charge?
Thank you,
regards Dan
