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BQ27Z746: How to evaluate the RSOC accuracy of fuel gauge in theory

Evan Peng
Intellectual 1395 points
Part Number: BQ27Z746

Hi,

The fuel gauge can report RSOC, but how to evaluate it's acuuacy and error in theory?

I have read some internal materials, some article and report introduce the experimental method to evaluate the accuracy, which records the report RSOC in a discharging circle, then calculate the real RSOC after this cycle, and get the error, as can be seen in the following website. This is simple and direct, but I would like to know if we can evaluate the final RSOC accuracy based on the meter accuracy and the Impedance Track algorithm accuracy. This may outstand our product better in theory. Could you please help to give some advice on how to evaluate the accuracy in theory?

A step-by-step guide to calculating battery gauge accuracy

Regards,

Evan

  • 0
    TI__Guru** 105760 points

    Hello Evan,

    I'm not sure exactly what you are requesting, the guide you linked shows how to calculate the error between true SOC which is calculate after a discharge and the values reported by the gauge (RSOC) this is the best way to verify the impedance track accuracy for your application.

    If you are interested in the impedance track theory we have an app note explaining high level the different aspects of the algorithm:

    https://www.ti.com/lit/pdf/slua364

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    TI__Intellectual 1395 points

    Hi Wyatt,

    I mean, to be short, can we get the transfer function from RSOC error to ADC error for our impedance track gauge?

    Regards,

    Evan

  • +1 in reply to Evan Peng
    TI__Guru** 105760 points

    Hello Evan,

    No I am not aware of this type of function. If you are concerned about the gauge ADC error playing a factor you can use external equipment to verify the true FCC and true RemCap in order to do a comparison of the gauge hardware and equipment hardware. The gauge ADCs are very accurate and provide enough resolution to keep 1% SOC accuracy with impedance track.

    Sincerely,

    Wyatt Keller