We have a 4S1P, 3430mAh battery design using the bq20z655-R1 gauge and our customer wants the batteries remaining capacity and
full charge capacity value to remain under 2500mAh to allow it to be compatible with exsisting equipment; otherwise it will not work.
We've used the 'Reserve Capacity' feature to enable us to meet this request.
The Gauge had its "Reserve Cap-mAh" set to 930mAh & "Reserve Cap-mWh" set to 14332, then a reset command 0x41 issued.
Please refer to Chart..
Initially, the FCC decreased by the reserve value (to 2311mAh) but what we found, was that during two learning cycles, when the VOK
was set during Charging, the FCC jumped back up to a value that indicated 'no reserve' (point A) until charge was terminated (point B)
and then RC was set to FCC (as it alone, should do) but when VOK clears again, the RC drops to a 'with reserve' level (point C) but
the FCC does not until discharging starts and then it also drops to a 'with reserve' level (point D) and behaves as it should
until the next VOK set and charging condition.
I suppose the main question is: Why does the FCC value go up 'too high' at point A?
Thanks,
Carl.
