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BQ27542-G1: Configuring and Calibrating the Gauge when using a known battery

Craig Carder1
Intellectual 510 points
Part Number: BQ27542-G1

Hello,

     I have a design using the bq27542 and I'm using a standard Panasonic 18650 cell.  I have found the cell in the Chemistry ID list.  What else do I need to do to calibrate the gauge?  Do I need to go through a learning cycle since it is a common cell?  What other steps do I need to take.

      The gauge is connected to an MCU in use, so what parameters do I need to load into the gauge from the MCU.  The gauge will not be programmed or calibrated prior to the MCU being used.  If I know what needs to be loaded, I can do so through the MCU.

Thanks

Craig

  • 0
    TI__Expert 4065 points
    HI Craig,
    Thank you for considering TI device in your design, so you need first to set battery parameters and select the ChemID that match your battery before doing gauge calibration and performing a learning cycle, please refer to the following documents for other Impedance Track devices as a guide on how to set bq27542 fuel gauge:
    1. www.ti.com/.../slua801.pdf ( Gauge Communication host MCU).
    2. www.ti.com/.../sluuah7b.pdf (Check "Programming the Configuration" section 4).
    3. www.ti.com/.../slua640b.pdf (Calibration of Fuel Gauge).
    4. www.ti.com/.../slua597.pdf (Achievement Successful learning cycle).

    Regards,
    Haidar
  • 0 in reply to Haidar Hamoo
    Intellectual 510 points
    Thanks,

    There's no .dfi file that I can download from someone who has done this before with this type of cell that I can use? I don't need it to be incredibly accurate. I just need it to match the basic battery parameters.
  • 0 in reply to Craig Carder1
    TI__Expert 4065 points
    You do not need dfi file for setting your key battery parameter (Design Capacity, Design Energy, Terminate Voltage, and Taper Rate), your MCU can do that as explained in document #2, (Quickstart Guide section 4), then you can read gauging results such as voltage, SOC %, Average Current, ...etc via your MCU by sending Standard Commands to the gauge, (you can find Standard Commands in bq27542-G1 TRM).
  • 0 in reply to Haidar Hamoo
    Intellectual 510 points
    Thanks Haider,

    I would like to program those 4 parameters as mentioned in the document. But I am unable to do so. The document refers to Gauge Studio but I am assuming this has been replaced by Battery Management Studio.

    The Full Charge Capacity listed on the Registers sheet is read only. I've programmed the correct capacity on the Parameter Q&A page but it is not updating on the Registers page.

    Using Battery Management Studio, how do I update Design Capacity, Design Energy, Terminate Voltage, and Taper
    Rate.


    Thanks

    Craig
  • 0 in reply to Craig Carder1
    TI__Expert 4065 points
    Graig,
    Did you make sure your gauge is unsealed?
    Regards,
    Haidar
  • 0 in reply to Haidar Hamoo
    Intellectual 510 points
    Yes, it is unsealed.

    If I do a Read from Gauge on the Parameter Q&A screen I see that the nominal design capacity is set to 3350 mAh which is what I set. But if I go back the Registers screen, Full Charge Capacity shows up as 961 mAh.

    I can click on the 961 and it brings up a dialog, but I can not change it.
  • 0 in reply to Craig Carder1
    TI__Guru* 76230 points
    Hi Craig,
    You can configure the gauge using a gg file extract. You program your chem id, modify an extracted gg file, and then program back on the chip. Then run a learning cycle before extracting your golden file. You do not need the paramter Q and A to succesfully configure your gauge.
    thanks
    Onyx