Hi - I need some help choosing the balancing resistors on my BMS. I have designed and built a prototype using the bq76940 with a 15 cell LiFePO4 test pack at approximately 48V under load and 52V fully charged. The cells are 10Ahr in capacity. My design is based on the slvu925b.pdf example evaluation module. The example uses 100 Ohm resistors.
This is what I believe: With 15 resistors this is 1500 Ohm in series and from a 56V charger this is 37mA max being discharged as heat through the 100 Ohm resistors. If my cells are 10000mAh this will take up to 270 hours to charge or discharge depending on the balancing that is needed. How can I reduce the balancing resistors to decrease the charge time to around 10 hours?
1000mA = 56 Ohm (total) / 15 = 3.73 Ohm resistors