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BQ34Z100-G1: Recommended LiFePO4 values for battery gage settings for PB parameters?

Richard Griph
Intellectual 530 points
Part Number: BQ34Z100-G1

I was wondering if there is a recommended default table or image file for recommended LiFePO4 values for the BQ34Z100-G1 battery gauge.  The BQ34Z100-G1 data sheet does not provide an in depth description of all the registers.  There are some registers that pertain to for Pb-Acid and NiMH batteries that would not apply to LiFePO4, and it would be helpful to know how to set those?  The battery chemistry matching tool provided CHEM ID of 435 which is listed as a LiFePO4.  The 400 series chem ID's all correspond to LiFePO4 batteries, does the battery gauge chip use the series number or info stored as part of the chemistry to ignore some of the register values like those that pertain to Pb-Acid and NiMH batteries?  If that is the case, is there some list of ignored register settings?

  • 0
    TI__Mastermind 25955 points
    Hi Richard,

    You're absolutely correct. The gauge uses the chemID number to mask functionality depending on the chemistry type. For LiFePO4, please make sure to set the LFP relax flag. Pb and NiMH settings are ignored for non Pb and NiMH cells.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Intellectual 530 points

    Thanks for the information.

  • 0 in reply to Richard Griph
    Intellectual 530 points

    The bq34z100G1 chip's "Pack Conifiguration" register has a PB_RESTART bit 2 which is listed and described as QPCCLEAR when using the battery management SW.  The FW rev number for the gas gauge chip is 0100_0_16-bq34z100G1.  I suspect when the data sheet was written the FW was an earlier revision and the bit got reassigned without the data sheet being updated?  I am attaching a print screen of what the tool says and what the data sheet says.  I have not been able to find a description of what the PB_RESTART bit function is and so I do not know how to set it.

  • 0 in reply to Richard Griph
    Intellectual 530 points

    I Iam reattaching the screen capture picture since I am not sure it got uploaded.

  • 0 in reply to Richard Griph
    TI__Mastermind 25955 points
    Hi Richard,

    Thank you for bringing the discrepancy to our attention. PB_Restart operates in the same way as QPCCLEAR. The feature clears Passed Charge that may have been accumulated towards a Qmax update when the gauge exits the relaxation state, if a DOD point has been set. This helps to prevent errors in the Qmax estimate due to the way that voltages of some battery chemistries, such as PbA, relax after charge and discharge.

    Sincerely,
    Bryan Kahler