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BQ27441-G1: DSG flag not turning true when the device in running only on battery

Scott Harsany
Prodigy 130 points
Part Number: BQ27441-G1
Other Parts Discussed in Thread: BQSTUDIO, EV2400

We have created a device that uses the reference layout for the BQ27441-G1.   If I leave the device in full power mode and disconnect from external power sources and only run on the battery. the DSG flag will be set properly.  If I allow the device to sleep (still burn low level of power) for 45 seconds and then wake up and check DSG flag it is always false.   What is it that I am sure I am missing here?

Thanks for any pointers.

Scott

  • 0
    TI__Guru 52115 points
    Hi Scott,
    Could you share your gg file?  I'd like to see your configuration.
    Also, could you connect the EV2400 to the gauge device after it wakes up and then capture a bqStudio log file?  Share the log file with us. 
    Andy
  • 0 in reply to Andy Liu (BMS)
    Prodigy 130 points

    Andy thanks!  I will try and use the tools you mentioned to extract the information you seek.   The board we designed is a custom PCA driven by an ESP32 and so the BQ27441 is attached to the i2c bus of the ESP32.  Can these tools still be used?

    Also Late last night I changed the memory data variable "DSG CURRENT THRESHOLD" (81 ,0) to 250.  It defaults to 165 and would never assert DSG flag,  But once I moved the value to 250 it worked perfectly ... added external power and DSG flag would go to ZERO and take external power away and it would go to ONE.  I am not sure I understand why moving it up works cause it seemed more likely to move it to a lower threshold.  But 250 works default of 165 does NOT work.  Hope this makes sense to you?

    Thanks,

    Scott

  • 0 in reply to Scott Harsany
    TI__Guru 52115 points

    Hi Scott,

    See my comments.

    The board we designed is a custom PCA driven by an ESP32 and so the BQ27441 is attached to the i2c bus of the ESP32. Can these tools still be used?
    [Andy] The EV2400 can be considered as an I2C master. If you have two masters on the same i2c bus, there might be some problems. I would suggest you only connect EV2400 to the gauge device.

    Also Late last night I changed the memory data variable "DSG CURRENT THRESHOLD" (81 ,0) to 250. It defaults to 165 and would never assert DSG flag, But once I moved the value to 250 it worked perfectly ... added external power and DSG flag would go to ZERO and take external power away and it would go to ONE. I am not sure I understand why moving it up works cause it seemed more likely to move it to a lower threshold. But 250 works default of 165 does NOT work. Hope this makes sense to you?
    [Andy] It makes sense to me. The discharge current threshold can be calculated as Design Capacity / (Dsg Current Threshold × 0.1). The default is Design Capacity / 16.7.

    If Dsg Current Threshold is set 250, the discharge current threshold will be lower (Design Capacity / 25)

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 130 points

    Thanks Andy!  This was very helpful.