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BQ40Z50-R1: bq40z50-R1 / Coulomb counting during cell balancing

Part Number: BQ40Z50-R1

Hi,

Please let me ask about coulomb counting during cell balancing. I understand that the charge current is bypassed during charging or at reset. Then the bypassed current during charging is not flowed to cell so this can't count as charge current. And also the  bypassed current at rest is not flowed through sense resistor so this can't count discharge current. In fact I think that the bypassed current will produce the error of calculated capacity. I'd like to understand about it so please share any app note or presentation material if you have.

Best Regards,

Satoshi / Japan Disty

  • Hi Satoshi-san,

    We use passive internal cell balancing for bq40z50-R1. This bleeds off current from the cell being balanced to BAT-, which balancing rate is set by the 100-ohm resistor and firmware data flash setting. The current does flow through the sense resistor to return to PACK-. Our gauge takes that into account in the cell current and capacity calculations.

    Here's an app note on cell balancing...
    www.ti.com/.../slyt322.pdf