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Compiler/BQ78350: SOC percent calibration

Harish SM
Prodigy 60 points
Part Number: BQ78350
Other Parts Discussed in Thread: , BQSTUDIO

Tool/software: TI C/C++ Compiler

We have a 29.4V 23.5Ah Lithium polymer battery pack with bq78350 BMS.

The full charge capacity IS 29.4V which is 100% SOC but it is showing a improper percentage value for 28.74V it should be around 90% but its showing as 22% how to change SOC parameter.  

  • 0
    TI__Guru* 81034 points

    Hi Harish,

    To get accurate SOC, make sure to follow the steps in the Gas Gauging section of the Using the BQ78350-R1 app note. You need to select the correct ChemID for your battery (this will help with the initial SOC estimation after Reset) and then follow the steps to generate the CEDV parameters for the device (this will ensure accuracy over current load and temperature once the gauge has gone through a full discharge cycle). 

    It looks like you are using the BQ78350 which is not recommended for new designs. You should use the BQ78350-R1 (or R2) instead. You can download the R1 firmware from here: http://www.ti.com/product/BQ78350-R1/toolssoftware. Or you can download the BQ78350-R2 firmware from its product page. You can load new firmware onto your device using the Firmware screen in BQStudio. In the firmware download, you will also find a .bqz file that should be copied into your C:\ti\BatteryManagementStudio\config\ directory (this will allow BQStudio to auto-recognize the new device).

    I also recommend updating BQStudio to the latest version available on ti.com - it looks like you are using an older version.

    Best regards,

    Matt

  • 0
    Prodigy 60 points

    Hi thanks for the help but how to change the Remaining capacity value in the register can you suggest me .The actual remaining capacity value is 21000mAh but it is reading as 5000mAh value

  • 0 in reply to Harish SM
    TI__Guru* 81034 points

    Harish,

    Did you initialize the Learned Full Charge Capacity parameter and the Design Capacity Parameter in on the Data Memory screen? Both of these should be initialized to the same value. After the battery completes a full qualified discharge, the Learned Full Charge Capacity will get updated.

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 60 points

    thanks Matt 

    this resolved my issue its been great that you supported me for thhis threads.

  • 0 in reply to Harish SM
    TI__Guru* 81034 points

    Harish,

    That's great to hear. Thanks for letting me know.

    Matt