BQ34Z100-G1: MAX ERROR Rises from 1% to 116% and SOC falls from 44% to 33% after 3 days of relax

Yunfeng TANG

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO

Hello,

after doing multiple discharges and loads for 85 hours, the SOC ended up at 44% (which was fine).

but then, this happened:
After 3 days of resting, the SOC value has decreased to 33% with max error of -116%. This is a problem we can't solve, could you helpe us?

You will find attached a screen sensor of the result, an export file of the datas and the cycles we ran with the battery 3 days before ir happened

Best regards,

YUNFENG

1507pb_apres_multiples_charges_decharge.gg.csv multiples charges decharges.log.

over 4 years ago

0 Yunfeng TANG over 4 years ago

Intellectual 300 points

hello, anyone has an idea of what happened there?

0 Vos over 4 years ago in reply to Yunfeng TANG

TI__Genius 10370 points

Yunfeng,

MaxError just counts up based on estimated CC error from the continuous cycles. I expect this pack started in an unlearned state (100% max error) then counted up to above 128%. This register in bqStudio is a signed value so it rolled over to the -116%. Please perform a proper learn cycle to reset the capacities and resistances of the pack.

When doing continuous cycling it is important to get a VCT event to ensure the gauge "resets" itself to know where it is

Thanks,

Eric Vos

0 Yunfeng TANG over 4 years ago in reply to Vos

Intellectual 300 points

Thanks Vos,

We found the problem, it was this:

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/508298/bq34z100-g1-max-error-parameter

Power management

Power management forum

BQ34Z100-G1: MAX ERROR Rises from 1% to 116% and SOC falls from 44% to 33% after 3 days of relax