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BQ4050EVM-561: CEDV Configuration for the first time

Venugopal S
Intellectual 640 points
Part Number: BQ4050EVM-561
Other Parts Discussed in Thread: BQ4050, GPCCEDV, BQ24610

I am planning to purchase the EVM of bq4050 for evaluation. In the first run, how does the firmware know the CEDV details of my battery pack? Does it obtain it from the selected chemistry or are there any other steps involved ??

  • 0
    TI__Guru 73830 points

    You can use the default OCV table that is loaded in the device for most Li-Ion cells. The gauge only uses the OCV table when the cells are first attached or if the gauge is reset. Ortherwise, it uses coulomb counting to track the capacity. You will need to use the online GPCCEDV tool to find the CEDV coefficients for you pack and then program them into the flash memory. You can then run a charge and discharge to update the FCC and export a golden file to be used in production.

  • 0 in reply to ThomasCosby
    Intellectual 640 points

    Dear Thomas,

                         I have been using the bq4050 along with bq24610 charger to charge/discharge a 28.6Ah Lithium ion battery pack. I have not run the CEDV tool to find the exact coefficients for my pack. I am using the default loaded values in the firmware. I am facing an issue with the way my battery is getting discharged. Please see the attached graph which shows RSOC and Cell Voltage1.

    After 26% RSOC, the value suddenly falls down to 7%. And it reaches to 0% at a much higher voltage of 3.4V, whereas I actually want to discharge it down to 3.0V.

    How can I rectify this issue and get a more faithful RSOC value? Some of the related parameters in the firmware are :

    Battery Low = 7%

    EDV2 = 3501 mV

    EDV1 = 3385 mV

    EDV0 = 3031 mV

    Although accurate SOC measurement is not of much concern for my application, I would like to specifically cut off the discharge at 80%DOD. For this I need a more faithful relationship between SOC and cell voltage.