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BQ40Z50-R4-DEVICE-FW: Cycle count data flash modification

Ted Ong
Prodigy 205 points

Part Number: BQ40Z50-R4-DEVICE-FW

Hi TI, 

We are running production with BMS BQ40z50-r4. 

Recently we have batteries with higher cycle count which we wish to clear it to 1 before shipment. 

the command "lifetime data reset()"  was used but not able clear cycle count to 1.

So we modify the Flash Table address 0x4380 directly to 1.

Is there any impact by doing this? Will this cause any error , like Max error?

 

  • 0
    TI__Guru** 105770 points

    Hello Ted,

    You should reset the cycle count to 0 before exporting your golden image to program on production. That is the proper procedure.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 205 points

    Hi Wyatt,

    Thanks for your replied, do you mean , there isn't any command to reset the cycle count after we program golden image to battery pack? 

    is there any details document on clearing cycle count on your website? I read through technical reference,bq40zxx Manufacture, Production, and Calibration, do not find anything on cycle count. 

    it is hard for production if we do not have any reset/edit feature on cycle count before shipment. 

    regards

    Ted

  • 0 in reply to Ted Ong
    TI__Guru** 105770 points

    Hello Ted,

    There is no command to reset cycle count, you just reset it in bqStudio in the data memory tab.

    It's not a requirement for going to production, but it would make sense to reset this to 0 if you are flashing it to a new battery to keep track of the cycles for each pack.

    This would be part of your golden image you flash into the gauge in production, it's not a separate command sent before shipment. Once it's in the golden image no other changes for Cycle Count is needed.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 205 points

    Hi Wyatt,

    I get one battery pack perform steps below:

    1)load golden image to the pack

    2)cycle a few rounds(charge/discharge) . Cycle count increase to 4

    3)use Battery management studio  set cycle count to 0 .

    4)charge the battery pack for a while, and i get max error 101%. 

    Do you encounter this before? 

  • 0 in reply to Ted Ong
    TI__Guru** 105770 points

    Hello Ted,

    Once you upload the golden image you don't need to reset the cycle count, it should already be set to 0 in the golden image. If you perform cycles with that pack, the cycle count should stay at 4.

    If the update status is indicating you are fully learned and the cycle count is 0, then MaxError should be low at 1%.

    Can you show a log of this behavior?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 205 points

    Attached the file here. why do i get 101%? since Max error maximum is 100%? 

    for the attached log, during sample 7, i set the cycle count to 1 but max error become 101% from 2%. 

    max error issue.xlsx

  • 0 in reply to Ted Ong
    TI__Guru** 105770 points

    Hello Ted,

    The MaxError will be over 100% if the Qmax Cycle Count is large than the Cycle Count (which is impossible without manual changes to the DF) It will correct on the first Qmax taken, or if you manually set both the Qmax Cycle Count and Cycle Count to the same value.

    Sincerely,

    Wyatt Keller