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BQ40Z50-R2: About relax mode

Sunrain
Intellectual 615 points
Part Number: BQ40Z50-R2


Hello，

I see two relax modes in 《Technical Reference Manual》, and they conflict。

1、Current < Quit Current for Chg Relax Time period or Current > (–) for Quit Current Dsg Relax Time period will enter relax mode

2、A relaxed state is achieved if the battery voltage has a dV/dt of < 4 µV/s.

Are these two relax's different? The first is that it is impossible to reach dV/dt of ＜4 µV/s。

One more question：

“These OCV readings are taken when the battery is in a relaxed state before and after charge or discharge activity” This OCV is the second relax，How do I know that OCV readings are taken and that OCV is valid?

Thanks

  • 0
    TI__Mastermind 27321 points

    Hello Sunrain,

    1- Both conditions apply for Relax mode. The gauge uses absolute value for when current is negative. See 6.3 Gas Gauge Modes in TRM.



    2- The dV/dt of < 4 µV/s condition is used for OCV measurements, not to determine when the gauge enters Relax state.

    The VOK flag indicates the OCV measurement is valid. See below.



    Regards,
    Jose Couso

  • 0 in reply to Jose Couso
    Intellectual 615 points

    Hello，

    1、The GaugingStatus()[REST] flag is set when a valid OCV reading occurs；

           How do you know the two ocv readings are taken?

    2、The [VOK] flag indicates the last OCV reading is qualified for the QMax update.

         If [REST] is set and [VOK] is cleared, but there is no QMAX update. So is this valid OCV reading is disqualified?

    Thanks

  • 0 in reply to Sunrain
    TI__Mastermind 27321 points

    Hello Sunrain,

    1- If you are logging, when you see the VOK flag toggling twice, this indicates that two OCV measurements have occurred. 

    2- I see the confusion, not all OCV measurements qualify for Qmax update. When VOK is set, it means it qualifies. The gauge takes OCV measurements every 1 hour in relax mode.

    Regards,
    Jose Couso

  • 0 in reply to Jose Couso
    Intellectual 615 points

    Hello

    1, [VOK] is only changed at the beginning of charging and discharging, which requires two relax to measure two OCVs?

    2、According to the Technical Reference manual, [REST] is set and [VOK] changes from 1 to 0, then QMAX should have been updated. However, from the current situation, sometimes QMAX is not updated, so [REST] and [VOK] cannot directly determine QMAX updates, and the technical reference manual does not say otherwise。

    Thanks

  • 0 in reply to Sunrain
    TI__Mastermind 27321 points

    Hello Sunrain,

    If it is the first Qmax update, 90% of passed charge is required. Please see below for all QMax update conditions.


    Regards,
    Jose Couso