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BQ40Z50-R2: SOH=0

user5768972
Intellectual 450 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50

Hello everyone.

I am using a BQ40Z50 r-2 to manage my battery.

I discharged the battery until the CUV worked, then did a charge operation to release the CUV.
At that time, I observed the SOH and found that SOH = 0 for about 2 seconds.
After 2 seconds, the SOH returned to normal.

Is this SOH state normal?
Is there any way to avoid this SOH=0 for 2 seconds?

  • 0
    TI__Guru** 106050 points

    Hello,

    For this kind of issue it is hard to determine if it's a momentary communication problem or the gauge is delaying reporting the SOH. Have you observed this on multiple devices? Does it happen every time you are in this scenario?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Intellectual 450 points

    Several devices were identified.

    They were in shutdown mode due to discharge, not CUV. (Threshold 2.3V)
    Immediately after waking up from shutdown mode, I could see the logs as above. ("watch" part... SOH is at 0% for about 2 seconds after waking up with 16V from external source).

    What could be the cause?

  • 0 in reply to user5768972
    TI__Guru** 106050 points

    Hello,

    I see the issue, the gauge needs some time to initialize before SOH will report accurately due to the methods used for SOH calculation (running a discharge sim for FCC at 25degC) In the newer R4 firmware this behavior has been resolved so we used a pre-saved value on startup from POR before the gauge recalculates the SOH so we don't report 0% for a couple seconds on startup.

    Sincerely,

    Wyatt Keller 

  • 0 in reply to Wyatt Keller
    Intellectual 450 points

    Your explanation helped me understand why.
    I will consider using R-4.
    Thank you very much.

    Takahashi