BQ40Z50-R2: SOC jump for varying discharge current

VASANTH MITHILACODY62

Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQSTUDIO

We are seeing FAH/RAH jump, when pack is discharged with varying load. FAH jumped from 19.671Ah to 5.895Ah whereas RAH jumped from 13.772Ah to 0Ah.

Attached is the BQstudio log and SREC file of the battery pack. Let us know what caused the sudden drops in FAH/RAH.

Regards,

Vasanth

over 6 years ago

0 VASANTH MITHILACODY62 over 6 years ago

Intellectual 475 points

Log file 2.zipSome more log data added.

0 Swaminathan Ramanathan75031 over 6 years ago in reply to VASANTH MITHILACODY62

TI__Expert 6575 points

Hi Vasanth,
It looks like the due to the really low impedance of the cells, the Fast Scaling is not behaving correctly.
When the RM and FCC are dropping the RaScales for the cells are becoming really high values, and this is a typical symptom when there is an issue in the fast scaling.
The best option in this case would be to disable fast scaling by setting the [RSOC_CONV] bit in "IT Configuration" to 0.
Currently your setting is as follows:
"Settings","Configuration","IT Gauging Configuration","d3fe","hex"
If you change it to:
"Settings","Configuration","IT Gauging Configuration","d3be","hex"
This will disable fast scaling and you should not see this drop.
Regards,
Swami

0 VASANTH MITHILACODY62 over 6 years ago in reply to Swaminathan Ramanathan75031

Intellectual 475 points

Hi Swami,

Thanks for the quick response.

After changing to d3be, we are not seeing any jump in the SOC during discharge.

But we continue to see FAH changes during end of charge/discharge event. One more observation that even though there is current flow, RAH has not started to increase for around 27 minutes (10A charge current). Refer to log file for more information.

Let us know any settings changes in the GG file could solve above mentioned issues.

Regards,

Vasanth

Log file 3.zip

0 VASANTH MITHILACODY62 over 6 years ago in reply to VASANTH MITHILACODY62

Intellectual 475 points

Hi Swami,

Any update on above query ?

Regards,

Vasanth

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BQ40Z50-R2: SOC jump for varying discharge current