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Original question:

BQ27426: Implementation conditions and impact of self-calibration and self-learning

BQ27426: Related problems of Fast Qmax 1

xianzhen cao
Prodigy 100 points
Part Number: BQ27426


Dear engineers of TI,

When BQ27426 is used in our project, we have some questions about of Fast Qmax:

1. DOD valid time register

This register is not described in the user manual. What does the set value of this register mean? How should we set this value when we use it?

2. Fast Qmax start related register

According to the description, only when the conditions are met can Fast Qmax measurement be entered. Then, what will be the impact of modifying the values of these three registers during the test?

In production, where should the values of these three registers be reset instead of using the default values?

thanks

  • 0
    TI__Guru 64266 points

    #1: The gauge requires that the cell stays in relax for this amount of time after taking an OCV measurement before it accepts this OCV measurement for a DOD0 calculation and update. Please leave this default.

    #2: Fast Qmax only works acceptably well, if charge starts and discharge ends in certain regions of the OCV curve and if the load is not too high. These parameters control when the gauge allows a Fast Qmax update. Please leave these values as default values. If you change them, you should first analyze how your cell behaves (it depends on the OCV curve) and if the behavior won't cause excessive Qmax (DOD) errors. The impact may be high error in Qmax and as a result inaccurate gauging.