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BQ34Z100-R2: Max Error set to 122% resetting Cycle Count number

Marco B
Prodigy 55 points
Part Number: BQ34Z100-R2
Other Parts Discussed in Thread: BQSTUDIO

Tool/software:

Dear TI Team,

After several tests to obtain the configuration for my gauge (including successful learning and optimization cycles), I extracted the Golden Image directly from bqStudio; but before doing that, I reset the CycleCount to 0. This probably caused MaxError to suddenly jump to more than 100% (I tried the same operations with a learned configuration with MaxError = 1% and I see the exact same behavior). Can you confirm that manually modifying CycleCount can affect the MaxError parameter? 

Eventually I tried to program another FuelGauge with the configuration with MaxError to over 100%, and tried to perform a few cycles: what I saw is that the MaxError dropped to 1% after two cycles, right after the end of charge. Can you please explain me how MaxError is calculated or how do I get a value close to 0%? The most important thing for me at the moment is to not get the parameter jumping suddenly to values close to 100%.

Thank you,
Marco

  • 0
    TI__Mastermind 25915 points

    Hi Marco,

    The image below describes cycle count. The behavior you described is not unusual, Max error should correct itself, once more information is learned by the gauge.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 55 points

    Hi Diego,

    Please see my further questions below:

    1. Can you confirm the manual reset of Cycle Count affect MaxError value? If yes, is it possible to create a golden image with Cycle Count = 0? 
    2. Are there any requirements to satisfy the auto correction of Max Error? For example the full charge conditions detection? Or a full charge/discharge cycle?

    Thank you for your help,

    Marco

  • 0 in reply to Marco B
    TI__Mastermind 25915 points

    Hi Marco,

    The MaxError() does nothing in terms of gauging, it simply tells you the max possible error at a given moment. What are you using this register for?

    1) Yes and yes.

    2) Please view table 2-4 in the TRM.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 55 points

    Hi Diego,

    I'm using this register to give a warning in case it exceeds 50%. What I understand from table 2-4 of the TRM is that MaxError() is incremented in the display by 1% for each increment of cycle count. Does it mean that if there aren't QMAX and Ra table updates, after 50 increments of CycleCount the value of MaxError() should be incremented by 50% too?

    Can you explain me better how can I create a golden image with CycleCount=0 without compromising MaxError?

    Thank you again,

    Marco

  • +1 in reply to Marco B
    TI__Mastermind 25915 points

    Hi Marco,

    Yes

    I would reset cycle count and increase cycle count threshold to its max value. Allow the gauge to take its ocv measurements and verify that max error has reset. Then go back into data memory set CC threshold back to the correct value and extract your golden image.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 230 points

    I am curious how to set cycle count threshold and CC threshold, what can those parameters influence?

  • 0 in reply to Jiaqi Yuan
    TI__Mastermind 25915 points

    Hi,

    CC threshold is cycle count threshold.

    The determine when cycle count will increment.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 230 points

    Hi Diego,

    How to select CC Threshold? My CC threshold is 900 mAh, and my cycle count is 101. anything wrong?

    Thank you

    Jiaqi

  • 0 in reply to Jiaqi Yuan
    TI__Mastermind 25915 points

    Hi Jiaqi,

    That depends on when you want cycle count to increment, see the description for cycle count below or in the TRM.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 230 points

    Hi Diego,

    Still very confused CC threshold value, is it related to capacity? should I revise it manually? and how to revise it? based on what's standard?

    Thank you

  • 0 in reply to Diego
    Prodigy 230 points

    Hi Diego, 

    Here you mentioned  "set CC threshold back to the correct value ", how to you select the correct CC threshold?

    Thank you

  • 0 in reply to Jiaqi Yuan
    TI__Mastermind 25915 points

    Hi Jiaqi,

    Jiaqi Yuan said:
    Still very confused CC threshold value, is it related to capacity?

    No, it is related to accumulated discharge and the CC (cycle count) threshold. When the accumulated discharge reaches CC threshold, cycle count will increment. 

    Jiaqi Yuan said:
    should I revise it manually?

    The default value is most likely not suitable for your application, but this is mostly dependent on when you want cycle count to increase.

    Jiaqi Yuan said:
    and how to revise it?

    You can write to the CC threshold parameter.

    Jiaqi Yuan said:
    how to you select the correct CC threshold?

    This is dependent on when you want cycle count to increase.

    Regards,

    Diego