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BQ27Z561-R2: config parameter required for bq27z561-R2 device

craig
Intellectual 510 points
Part Number: BQ27Z561-R2
Other Parts Discussed in Thread: BQ27Z561, BQSTUDIO

Tool/software:

Hello,

Trying to confirm what 'minimally', is required. Pulling this info from a combination of the TRM and b27z561 evm guid (note this is not R2) - these are the config parameters required for bq27z561 device:

  • Qmax Cell 1 = Design Capacity = batter_pack_capacity mAh   --Do I need to program Design Capacity 'cWh' mentioned in 4.7.1 of TRM

  • Design Capacity- Do I need to program this or does the Qmax value get passed from the Qmax Cell 1 automatically?
  • Design voltage ??? --Not mentioned in bq27z561...assuming yes.

  • Term Voltage = ‘system’ cutoff voltage (where 0% charge is indicated)

  • Charge Term Taper Current = battery_pack_capacity/20 (recommended)

  • charging voltage -Data sheet charging voltage, mention in 7.2.1 of evm:

    [Advanced Charge Algorithm][Low/Standard/High/Rec Temp Charging][Voltage]: This parameter
    should be updated to the maximum charging voltage of the battery to be used. For a typical Li-Ion battery
    this value is between 4.4 V to 4.2 V

    --How is this specified? Can this be left at default?

  • Chem_ID/chemistry -Handled in Chemistry program through bqstudio.

  • Enable internal temp sensor (needed for our design)


    Does the chemistry programming update any of the parameters outside chem data and chem_id?

    Any other items I'm missing?

    Does the device have to learn if using preexisting chem data (chem id and data)?

  • 0
    TI__Mastermind 37761 points

    Hello Craig,

    So what is minimally required would be any data memory parameter that is required to complete the Learning Cycle: https://www.tij.co.jp/jp/lit/an/slua903/slua903.pdf

    You should not manual change Qmax cell 1, this value is updated by the gauge whenever it makes a Qmax update.

    You will need to program Design Capacity cWh, Design Voltage, Design Capacity mAh, Term Voltage, Charge Term Taper Current, Dsg Current Threshold, Chg Current Threshold, and Quit Current.

    Charging Voltages from the advanced charge algorithm can be left at default. Advanced Charge Algorithm is mainly used if your system includes a smart charger.

    ChemID is important and should be the first thing to program. ChemID also programs some default Ra table values.

    Regards,

    Nick Richards

  • 0 in reply to Adrian
    TI__Mastermind 37761 points

    Hello Craig,

    Didn't see the last question at first. Yes, the device will need to learn. That is the purpose of the Learning Cycle, which I linked the document above.

    Regards,

    Nick Richards

  • 0 in reply to Adrian
    Intellectual 510 points

    Thanks, Do you guys offer learning as a service?

    My company based out of Houston, TX

    -Craig

  • 0 in reply to Adrian
    Intellectual 510 points

    So this statement regarding updating the qmax cell 1 is wrong or it only applies to the legacy bq27z561 device???

    www.ti.com/.../sluubu0a.pdf

    7.2.1 Important Data Memory Parameters to Change
    This section outlines the minimal critical settings that should be changed for even the basic evaluation. A short
    description is included which can be used as a recommendation how to set the parameter value. Additional
    updates are needed for a production setting.
    1. [Gas Gauging][State][Qmax Cell 1]: This value should be updated to be the default design capacity of the
    battery being used. It represents the full unloaded chemical capacity of the cell. This value is updated by the
    gauge when proper learning is performed and in the field over the life of the battery.

  • 0 in reply to craig
    TI__Mastermind 37761 points

    Hello Craig,

    We do not offer learning as a service. Qmax Cell 1 is a parameter that can be changed by the user and if this is for the first configuration can be changed to the Design Capacity. However, I don't recommend manually changing this value and instead just completing a learning cycle so the Qmax Cell 1 parameter is calculated by the gauge and updated to the correct value. It is very rare that the design capacity is the same as the true Qmax value.

    Regards,

    Nick Richards

  • 0 in reply to Adrian
    Intellectual 510 points

    So say TI releases an updated firmware...Can I export my learned data .df.ds, upload the new firmware, then upload the df.ds file to maintain learning?

  • 0 in reply to craig
    TI__Mastermind 37761 points

    I can't give a definitive answer on that question because it will depend on the changes that were made in the new firmware. If the new firmware changed memory locations for certain data memory parameters then the df.ds file will not be compatible with the updated firmware.

    Regards,

    Nick

  • 0 in reply to Adrian
    TI__Mastermind 37761 points

    However, I will add that the most important parameters for learning are the Ra table and Qmax value. Those values can be manually changed by you to maintain learning.

  • 0 in reply to Adrian
    Intellectual 510 points

    Can Dsg Current Threshold, Chg Current Threshold, and Quit Current be left a default as well?

    How do I determine these?

  • 0 in reply to craig
    TI__Mastermind 37761 points

    Hey Craig,

    These values will be dependent on the capacity of the battery you are using. We refer to capacity as "C". So Dsg Current Threshold can be set to a value lower than C/10. I recommend C/25. So for example, if the capacity of your battery is 1000mAh, I would set Dsg Current Threshold to 40mA. Chg Current Threshold should be set to a value smaller than the Charge Term Taper Current. Quit Current should be set to a value smaller than Dsg Current Threshold and Chg Current Threshold.

    Regards,

    Nick