BQ40Z80: Balancing at rest / sleep does not work.

richard wilson

Part Number: BQ40Z80
Other Parts Discussed in Thread: BQSTUDIO

Hi team,

The BQ40Z80 chip will balance during charge without problem. Balancing stops when the FC flag is set and never restarts even after an hour wait ( balancing start time) . I have had issues with completing a conditioning cycle, even though the correct procedure has been followed a couple of times, the CF flag is still set. I'm wondering whether the lack of a complete conditioning cycle is the issue?

Can you advise, I have attached the GG file.

Thanks

RichardBattery_Monitor_7S_R5_Software_2023_01_13.gg.csv

over 2 years ago

0 Wyatt Keller over 2 years ago

TI__Guru** 105860 points

Hello Richard,

The gauge should only balance after a learning cycle has been completed, from your .gg file I'm not sure if this has been done since it is set to 0x0C which is not normal, the expected values we usually see are 0x06, 0x04, 0x0e and 0x02.

the CF flag being set indicates that your max error is too high, which is usually due to the learning cycle not being completed or a large number of cycles of been elapsed with no Qmax or Ra table update.

Can you share the BQStudio log of your testing?

Also note that the BQ40Z80 does not support 7S configurations, 6S is the max.

Sincerely,

Wyatt Keller

0 richard wilson over 2 years ago in reply to Wyatt Keller

Intellectual 585 points

Thanks Wyatt, here is the discharge data from the learning cycle. For some reason , I don't have the charge log. I can confirm that I have 7 cells connected .

Battery7SDischarge_C_over_5.log

0 Wyatt Keller over 2 years ago in reply to richard wilson

TI__Guru** 105860 points

Hello Richard,

Your data shared does not make sense, LStatus should never be reported as 12 unless it was manually modified. The correct sequence for update status/LStatus would be 0x00->0x04 to start gauging. 0x04->0x05 first Qmax. 0x05->0x06 Ra table updated (this is what your golden image should be) once it is in the field it will update from 0x06 to 0x0e to enable cell balancing.

I'm not sure the root cause if the data was corrupted or it was manually changed accidentally, I would recommend if you don't have the logs showing the proper sequence of Lstatus then re-run the learning. And make sure that 6S is the maximum cell configuration used.

Sincerely,

Wyatt Keller

0 richard wilson over 2 years ago in reply to Wyatt Keller

Intellectual 585 points

I have not modified Lvalue, I can't say why it is value 12. I'll reset the device and go through the learning cycle again.

0 Wyatt Keller over 2 years ago in reply to richard wilson

TI__Guru** 105860 points

Hello Richard,

Sending the reset command will not reset the device flash values, it essentially just clears the RAM. You would need to re-upload your golden image, which should have Update Status = 0x06. Or if you are restarting the learning you can upload the golden image then manually set update status to 0x00.

Sincerely,

Wyatt Keller

0 richard wilson over 2 years ago in reply to Wyatt Keller

Intellectual 585 points

Hi Wyatt, I am a bit concerned , have you changed the chip design to make the chip only 6 cell? I have previously used the chip with 7S without problem, but I am now running into all manner of problems with our new build where cell 7 is not read.

Thanks

Richard

0 richard wilson over 2 years ago in reply to Wyatt Keller

Intellectual 585 points

Thanks

Richard

0 Wyatt Keller over 2 years ago in reply to richard wilson

TI__Guru** 105860 points

Hello Richard,

There has been no hardware changes to the BQ40Z80, it is still the same silicon. You should still be able to read the 7th cell voltage, there is nothing preventing the readings. It's not recommended to use the 7th cell.

Sincerely,

Wyatt Keller

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BQ40Z80: Balancing at rest / sleep does not work.