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BQ28Z610-R1: why Cell Balancing Does not work?

Yongki Jeong1
Intellectual 545 points
Part Number: BQ28Z610-R1
Other Parts Discussed in Thread: BQSTUDIO

Hi Ti

When I checked the SDV alarm, the cell balancing was broken.

Upload the GG file and the status window.

   1)  Is the setting wrong?

   2)  If the battery continues to be used without relaxation time after charging, does Pure Gauge not do cell balancing?

   3)  Is there no automatic recovery for SDV alarm?

   4)  If cell balancing is out of whack like this, how long does it take to rebalance?

8551.Data Memory.gg.csv

Thanks

  • 0
    TI__Guru** 105590 points

    Hello Yongki,

    You should clear all your protection cases before cell balancing, it looks like you have update status as 0x0E which means cell balancing is allowed if it is enabled. 

    CUV protection is also triggered, one of your cells is at 711mV and the other is over 2800mV, this kind of unbalanced is extreme and the pack should be permanently disabled and not try to cell balance.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Intellectual 545 points

    Hi keller

    In terms of settings, is there not any problem with Cell Balancing?

    Initially, the cells were not unbalanced.
    However, as the battery is used, there seems to be an imbalance between the cells more and more, and I am curious as to the cause of this.

    Sincerely

    Jeong

  • 0 in reply to Yongki Jeong1
    TI__Guru** 105590 points

    Hello Jeong,

    Your configuration indicates you only balance in charge mode, you can also enable balance at rest to give the gauge more time to balance the cells.

    This is quire an extreme imbalance, this would indicate the cell impedances are not matched and may be too high for the gauge to keep correcting, especially if it's only balancing during charge.

    Do you have a bqStudio log of the batteries being cycled that show the voltage deviating?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Intellectual 545 points

    Hello Keller

    You captured the Status window incorrectly. To correct, it was not an extreme voltage deviation.

    But why doesn't recovery work even after charging?

    Since voltage deviation did not occur while writing LOG, I do not currently have LOG.
    After battery learning, a voltage deviation occurred after using the battery to which the SREC file was input for about a month.
    I share SREC files.

    And if learning data is needed with a battery with voltage deviation, I will start learning anew.

    2610_1_01-bq28z610R1_210624.zip

    Sincerely

    Jeong

  • +1 in reply to Yongki Jeong1
    TI__Guru** 105590 points

    Hello Jeong,

    I think you may need to get better cell balancing by using external FETs or try enabling the cell balancing more often to prevent the deviation in REST.

    The gauge can only balance so quickly, it may take multiple cycle to correct a cell imbalance.

    Sincerely,

    Wyatt Keller