BQ27441-G1: Erroneous Full Charge Capacity

Alex Chapoulie

Part Number: BQ27441-G1

Hi all,

I would like to use a battery that I can disconnect and reconnect. For this purpose, I followed the BQ27441-G1 Quickstart guide and save the Ra Profile and QMax Cell 0 in the processor non volatile memory as preconised.

On POR detection, the Ra Profile (Ra0_0 to Ra0_14) and QMax Cell 0 are written back to the gauge flash. The Config Update Mode is exited using the ExitResim command.

The gauge default design capacity is 1340mAh, my battery is a 2000 mAh (by the way, the Design Capacity, Design Energy, Taper Rate, and Taper Voltage, are correctly set in the gauge flash data).

When I fully charge the battery, the estimated full charge capacity is around 2080mAh. If I unplug the battery and plug it again (flash restored), I expected to have a full charge capacity around the previous value but instead I get around 1280mAh.

What did I miss?

Thanks,

Alex

over 5 years ago

0 Alex Chapoulie over 5 years ago

Prodigy 100 points

Investigating on the subject, I discovered that performing a Soft Reset instead of ExitResim to leave the Config Update mode does the job... and then solved my problem.

But, consquently, I do not really understand what is the ExitResim command purpose.

0 Dominik Hartl11 over 5 years ago in reply to Alex Chapoulie

TI__Guru 61536 points

The gauge will not take an OCV if you issue EXIT_RESIM. It will just run a sim but it won't re-init the whole algorithm with the new config. You must use SOFT_RESET if you completely reconfigure the gauge.

0 Alex Chapoulie over 5 years ago in reply to Dominik Hartl11

Prodigy 100 points

OK this is clearer to me now. Thank you, I may have missed this detail in the documentation.

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BQ27441-G1: Erroneous Full Charge Capacity