Other Parts Discussed in Thread: GPCCHEM, BQ27541, BQ40Z50-R2
Good afternoon,
I am working on a legacy product using the bq20Z80A-V110 gas guage. The battery pack consists of 8x2.6Ah cells in parallel per series (3S8P) for a total of 20.8Ah for the pack. I am not able to get a good IT calibration for proper capacity tracking.
I have confirmed I am using the proper chem ID using GPCCHEM (this cell is also used in smaller pack designs and the IT works very well on those packs). For this larger pack, when discharging, the gas gauging will track until ~20% remaining capacity and then stop updating, even thought the pack continues to discharge. All parameters associated with IT (Relative State of Charge, Absolute State of Charge, Remaining Capacity, etc..) stay constant at ~20% until the discharge stops and the cells relax. At that point, the capacity parameters recalibrate and update to the expected ~0%.
I remember reading that the older bq27541 single cell gas gauge had an internal discharge/charge capacity accumulation counter that maxed out at 16,384mAh. 80% of a 20,800mAh pack is 16,640mAh, very close to that 16,384mAh limit.
Can anyone confirm that the bq20Z80A has this same counter and this stalling at ~20% capacity is expected behavior for this larger pack? Thank you
