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BQ28Z610 Max Error Parameter

B-A
Intellectual 720 points

Other Parts Discussed in Thread: BQ40Z50-R1, BQ28Z610

Good afternoon,


I have a few questions regarding the Condition Flag (CF).

First, what is the significance?

I only see this mentioned once in the Technical Reference Manual (TRM). It is based on a MaxError() SBS command and a Max Error Limit parameter of which no description is provided.

Based on the previous statement, Max Error of what?

I assume this has something to do with SOC estimation based on Qmax and resistance updates, but I don't believe the TRM specifies what kind of error this is. From another post (https://e2e.ti.com/support/power_management/battery_management/f/180/p/57146/204793#204793, a reset will apparently result in max error being set equal to 100%. I do not see the significance of this. A reset event, according to the post, results in max error of 100% which is still not greater than the Max Error Limit parameter.

The state of the CF flag also determines whether a "Condition Cycle" is needed or not. Is the TRM equating a "Condition Cycle" with a "Learning Cycle", if not, could a "Condition Cycle" definition be provided?

Thank you for your time.

Blake

  • 0
    TI__Guru* 76230 points

    Hi Blake,

    pls refer to the TRM for the bq40z50-R1. This has further details on the max error. The bq28z610 is a stripped down version of that device. For most batteries, the capacity depreciates  by 5% with every 100 cycle. If 100 cycles elapses without a qmax update, max error increments by 5%. if  2400 hours elapse after the last qmax update, max error increments by 5%. 

    I am not certain if the  time cycle equivalent and the cycle delta parameters were stripped from this device or hidden given that they are what control max error increments which in turn control the CF flag. Given that you don't have the option to set those two parameters, i would say don't worry about the max error. It doesn't affect the gauges functionality.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    TI__Guru* 76230 points
    Blake
    I just verified from our firmware engineer for the device that max error was taken out. That means the CF flag functionality is removed.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Intellectual 720 points
    Sounds good, thank you Onyx.