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BQ34Z100EVM: State of charge and discharge current not updating

IOANNIS ZOGRAFOPOULOS
Prodigy 10 points
Part Number: BQ34Z100EVM
Other Parts Discussed in Thread: BQSTUDIO, GPCCHEM

Hello,

I have recently tried to implement a gauge on the Samsung INR-18650 -25R (CHEMID: 2068) in order to log state of charge and voltage while discharging at a constant 500 mA (C/5)

However, I have been able to successfully log only the Voltage of the cell. The state of charge drops from 100% to 0% while the battery is around 3.5V which should not be the case at it should go down to 0% at around 2.8V. Also in my log file, the discharge current stays at -500 mA which is the calibrated value and not the actual measured value. 

I have seen something about a learning cycle but I dont see an option to configure one. Also, I am not certain about the level of detail the calibration requires in order to gauge properly. 

I am very new to the EVM2400 any help would be appreciated.

Thank you!

regards,

Yannis

  • 0
    TI__Mastermind 25955 points
    Hi Yannis,

    Please flash the default firmware onto your board and follow these steps as described in the quickstart guide:

    www.ti.com/.../sluubv2

    Prior to connecting your cells, utilize a power supply as a stand-in source (as shown in the quickstart guide) for the battery pack and perform the following calibration:

    1) CC Offset and Board Offset together
    2) Current Calibration ( training.ti.com/bq34z100-g1-current-calibration )
    3) Voltage Calibration ( training.ti.com/bq34z100-g1-voltage-calibration )

    With the board now calibrated, we will need to log the battery to determine the proper chemID match.

    If cells are only being used in series and not parallel, a single cell may be connected to perform this match. If cells are being used in parallel, configure the cells as if there is only 1 series cells and tie the rest in parallel. For example, if your system is 5S2P, connect the cells as 1S2P. If you cells are 7S1P, connect the cell as 1S1P.

    Do not adjust the series value on the gauge at this point, we are only using it as a logger. Take a log using bqStudio and follow th steps as described in this document:

    www.ti.com/.../slva725

    Once the log is taken, format the log and the config file as described in the document above before submitting the archive to the gpcchem tool:

    www.ti.com/.../gpcchem

    The tool will send back a chemID match, the proper chemID to use with the cells.

    Once this is complete, is it time to configure the gauge:

    Follow the steps in section 8 of the Datasheet to configure the hardware including the external divider (if using the evm, use the voltage divider values discussed in the voltage calibration video).

    Next, follow the steps in section 8 to configure the dataflash for gauging.

    Then, program the chemID using the chemistry tab of bqStudio.

    With the device now configured, run a learning cycle, as described in this app note:

    www.ti.com/.../slua903.pdf

    Ensure that update status changes from 0x04 to 0x06.

    Sincerely,
    Bryan Kahler