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BQ40Z50-R1: Battery shut down unexpectedly

BatteryEngineer16
Prodigy 45 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50

Hello!

We have had a problem with some batteries designed with BQ40z50-R1.
They have after a while in service (months) shut down into a mode where it is not possible to wake them with a charge pulse, and they won't communicate on the SMBus.
The only way to wake them has been by removing and re-connecting the cells. And after the cells have been connected again, the battery works fine, as if nothing had happened.
Life time logging is unfortunately not activated so it gives us no clues as to what could have happened.

The cells are around 4V so the batteries are not discharged.

What could have happened to the batteries to put them in this very deep state of shutdown?

  • 0
    TI__Mastermind 42535 points

    Hi,

    The gauge is supposed to wake up from sleep on a charger attach. Without your srec we can only speculate as to what may have happened. As you mentioned, unfortunately we can't reason what happened unless lifetime logging was enabled.

    We haven't encountered such issues from the field and there are no reports of failure to wake up on charger connect. However, we advise you to update to the latest fw rev as it does contain a few fixes.

  • 0 in reply to Batt
    Prodigy 45 points

    Hello Batt, thank you for your answer.

    I have attached the gg-file to this post.

    Previous batteries had the BQ40z50 (not R1) and we then made a change to the R1-version. No other change in the electronics were made.

    As far as we know, these problems has not been seen with the old version of the chip.

    We have just launched an updated version but since we don't know what caused this problem, we don't know if the problem is still present.

    Parameter Settings for BMS.zip

  • 0 in reply to BatteryEngineer16
    TI__Mastermind 42535 points

    One suggestion I can make is set NR=0 if your battery is removable. That way you can use the sys present pin to toggle fets on and off and enter a low power mode. Also, this will help with battery detection and turn on fets when system is up. Other than that your settings are alright.