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BQ40z60EVM - BMS parameters to new battery

Gilson Fernandes
Prodigy 110 points

Hello,

I'm evaluating the BQ40Z60-EVM with 3 LI-ION batteries with the following characteristics:

Nominal Capacity - 860mA.
Nominal Voltage - 3700mV
Charge Current -  Standard 0.2C, Max 1C
Charge cut-off Voltage - 4200mV
Standard Discharge Current - 0.2C
Standard Discharge Current -  2C
Discharge cut-off Voltage - 2750mV
Impedance - 300mOhms

After setting some parameters in BMS, I'm facing some issues:

  1. Battery charge status is not showing the correct values in percentage.
  2. Max Error is reporting 100%
  3. During charging, BMS report Charge Overload, but only one of the batteries reach 4200mV, and the other two has 3800mv and 3900mV respectively. Which looks like that the battery balance is not working.

Attached the gg.csv file.

LI063048A.gg.csv.zip

  • 0
    TI__Guru 73830 points

    Gilson,

    You have not completed the optimization cycle, so I would not be too concerned about the OC error at this time. I would disable the OC protection fault until the optimization cycle has been completed. It looks like you are still using the default ChemID. You need to update the the chemistry to a ChemID that matches your cell. You have the Load Select set to 7, which is Max Avg I Last Run and this is -2000 in your file. That is over a 2C rate and this could be part of the reason for the capacity error. This should improve after the optimization cycle.

    You can use this process for the optimization cycle.

    Burned default SREC and updated all parameters of data memory (especially Qmax and design capacity).

      1. Charge the pack to charge termination.  
      2. Wait until the “REST” flag get set.
      3. Discharge the pack at a rate between C/10 and C/5 to the Termination Voltage.
      4. Wait until the “REST” flag get set. Qmax should update and the Update Status flag should increment to 05.
      5. Charge the pack to charge termination.  
      6. Wait until the “REST” flag get set.
      7. Discharge the pack at a rate between C/10 and C/5 to the Termination Voltage.
      8. Wait until the “REST” flag get set. The Ra table should update and the Update Status flag should increment to 06.

    Tom