BQ40Z60: RSOC/ASOC indication drops gradually when part is idle but powered

Bert van Kraaij

Part Number: BQ40Z60
Other Parts Discussed in Thread: GPCCHEM

During testing of our battery board (cell configuration 4S2P) I found that the indicated battery capacity (RSOC/ASOC) drops over time when the board is on external power and the charger and/or the fets are disabled. When I than charge the set, it will not reach 100% charge level any more (because the cells are not discharged). Only after a full discharge of the pack I can reach 100% RSOC again.

I have included a log file of this case. The board is on external power, with fets and charger disabled with a full battery. The RSOC starts at 100% and drops with stes in 24 hours to 67%. The workaround is simple of course (don't disable the fets or the charger) but I wonder what causes this behavior. idle_mode.log

over 6 years ago

0 Batt over 6 years ago

TI__Mastermind 42535 points

Can you please send me your config gg file and your srec to check this out? I believe this may be chem ID parameter related.

0 Bert van Kraaij over 6 years ago in reply to Batt

Prodigy 60 points

Hi Batt,

Thanks for your reply. I included both files below.

Regards, Bert

board_1520_20180827.zip

0 Batt over 6 years ago in reply to Bert van Kraaij

TI__Mastermind 42535 points

Hi Bert,

Have you actually characterized your cell to find a matching chem ID or did you pick it up from the chem ID panel defaults?

Please use GPCCHEM if you have not matched your cell and then try the test.

0 Bert van Kraaij over 6 years ago in reply to Batt

Prodigy 60 points

Hi Batt,

Thanks for your answer. I did not characterize my cells. I just took a LiFePO4 configuration with the approximate capacity from the database.

I will follow your suggestion to get a better chemical match.

Best, Bert

0 Batt over 6 years ago in reply to Bert van Kraaij

TI__Mastermind 42535 points

Thanks, Bert. We are available to help you if you have further questions.

0 Bert van Kraaij over 6 years ago in reply to Batt

Prodigy 60 points

Hi Batt,

I created a discharge log and submitted the data to the GPCCHEM estimator. It turned out that the chemical ID that I used was not even in the top-15 list. I changed the chemical ID to the proposed best-fit value and thta solved my issue. Thanks for your help,

Kind regards, Bert

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BQ40Z60: RSOC/ASOC indication drops gradually when part is idle but powered