BQ40Z60: SoH calculation

Hi Batt,

I don't want to tweak the SoH, I want to tweak the FCC. In this case, the cell-pack has a max calculated capacity of 20Ah with the cell-voltage from 4.2 - 2.5V. I want to limit the cell-voltage from 3.9 - 3.2V, this gives me approximate 11.6Ah (measured QMaxPassedQ during discharge).

This means a nameplate capacity of 11.6Ah but how do I get the correct SoH calculated?

Thanks,

Rob

Hi Bat,

I've changed the charging voltage and the charge termination. I can't get the BQ40Z60 to learn the correct capacity therefor the SoH is all over. See attached  *.txt file, this is the *.srec file.

Thanks,

RobNCR_B_6P_XTD.txt

Hi Bat,

getting further I've managed to get the SoH correct, at least it looks that way. Encountered another strange behaviour.

During charging, the RSOC and ASOC are running practically synchron. When nearby full, RSOC = 100% and ASOC is 97% the ASOC suddenly drops back to 54%. After hitting FC, the ASOC jumps to 102%. See attached log file.

Best regards,

RobNCR_charge_2.log

Hi Batt,

thanks for the info.

I had to do several cycles to get everything in line. I am reproducing this now with half the amount of cells and, obvious, capacity. ASOC, RSOC and SOH take time to get accurate. Needed to set the Qmax delta to 100% and the Qmax upper bound to 230% else it would not learn since the actual capacity is much higher compared to the used capacity / nameplate capacity.

Another question. I see the BQ40Z50 is adviced over the BQ40Z60. Is there a specific reason for this I have to take into account for future designs?

Thanks,

Rob