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Original question:

BQ76952: About Setting: Configuration Vcell Mode with all bit set to zero.

BQ76952: What is the value of VCellMode if using a 13S battery?

Mo Mizzi
Intellectual 290 points
Part Number: BQ76952

Tool/software:

Hi,

I notice 0xFFFF or 0x0000 being set, if 16S were used. And I also saw, the Software Development Guide show an example of 9S , setting it as 0x037F. I'm not sure I follow the logic to derive what I need to pass in for a 13S battery pack. I'm using an external MCU to communicate with the BQ76952 over I2C.

Any help is much appreciated.

Thank you.

  • 0
    TI__Genius 17795 points

    Hello Mo,

    Thank you for your patience over the holiday. 

    Not every system uses all 16 cell input pins. Vcell Mode helps the device disable the protections of cells that are shorted together or used to measure interconnect resistance between cells, so they do not trigger when using less than the default 16 cells.

    Which cells that are chosen in Vcell mode depend on how you have your cells shorted as different users short it differently.

    If you are using this same schematic: 1616.13S_BatteryPack.pdf , I believe your Vcell Mode configuration should be: 0x87FF.

    Section 13.3.2.19 Settings:Configuration:Vcell Mode     from the technical reference manual may help understanding how to use Vcell Mode more when looking at the register field descriptions.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Intellectual 290 points

    Hi Alexis,

    Thank you for clarifying this point and pointing in the right direction. Yes, you are correct, I'm working with the same schematic you have referred. 

    Although, just want to double check. I think the 0x87FF would account for 12S. For 13S (referring to my schematic), I'm guessing it's 0x8FFF. Please correct me if I'm wrong. Reason being, Cell-12 is shorted with 13,14 and 15.

  • +1 in reply to Mo Mizzi
    TI__Genius 17795 points

    Hello Mo,

    Mo Mizzi said:
    Although, just want to double check. I think the 0x87FF would account for 12S. For 13S (referring to my schematic), I'm guessing it's 0x8FFF. Please correct me if I'm wrong. Reason being, Cell-12 is shorted with 13,14 and 15.

    You are correct. I had missed that connection.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Intellectual 290 points

    Awesome. Thanks for confirming.