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Original question:

BQ40Z50-R1: BQ40Z50-r1 CUV

BQ40Z50-R1: Cycle Delta

Needhu Gunasegaran
Intellectual 2890 points
Part Number: BQ40Z50-R1


Dear Team,

Need your support on a customer question.

Could you explain how the Cycle Delta is calculated? Customer wants to know if they could consider to reduce the Cycle Delta from the TI suggested default 0.05% to 0.01%?

Why is the Cycle Delta default set to 0.05%?

Thanks and Many Regards,

Needhu

  • 0
    TI__Expert 8365 points

    Hi Needhu,

    After a valid QMax update, each passed time period of Time Cycle Equivalent and each increment of CycleCount() will increment MaxError() by Cycle Delta. 

    Therefore, changing the value of Cycle Delta from 0.05% to 0.01% will cause the reported MaxError() to increment 5x slower upon triggering a CycleCount() update or passing a time period of Time Cycle Equivalent.

    Best,

    Jackson

  • 0 in reply to Jackson DiGiovanna
    TI__Intellectual 2890 points

    Hello Jackson,

    The customer has the following question.

    • How is the Cycle Delta calculated?
    • Why is the Cycle Delta default set to 0.05%?
    • What effect (except a slower MaxError increase) will the change from 0.05% to 0.01% have?

    Could you answer the questions?

    Thanks and Many Regards,

    Needhu

  • 0 in reply to Needhu Gunasegaran
    TI__Guru** 105960 points

    Hello Needhu,

    The cycle delta is set based on the expected deviation from the learned Ra and Qmax values caused by each cycle. Cycle delta can vary per application, if your battery is designed for longer not high power, your delta cycle may be less. If your battery is designed for high power but less cycles, the delta cycle might be higher.

    The max error won't have an effect on gauging, it's used more used as an indicator for when another cycle needs to be done for the gauge to learn Qmax and the Ra table again.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    TI__Intellectual 2890 points

    Dear Wyatt,

    Thanks for the feedback.

    Have a follow up question here.

    Since CycleDelta as you said is the ‘expected deviation’ form Ra and Qmax with each cycle, what usage scenario does the 0.05% default value represent? Will this parameter be affected by a particular cell mode (some cell may age faster than others under identical usage conditions).

    Thanks in advance,

    Needhu

  • 0 in reply to Needhu Gunasegaran
    TI__Guru** 105960 points

    Hello Needhu,

    The reason for the 0.05% change is based on observed data, this can be changed based on the application. There's no way to correlate exactly how much the deviation would be per cycle because there's always variance especially between applications. You can see the gauge resets the Max Error lower when an Ra update or Qmax update occurs.

    The value is not exact, it is just used as a reference to indicate weather another Qmax and Ra update are needed.

    Sincerely,

    Wyatt Keller