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BQ34Z100: How does the impedance update mechanism and the DOD-final calculation work?

zed
Prodigy 30 points
Part Number: BQ34Z100
Other Parts Discussed in Thread: BQSTUDIO

Tool/software:

Hello, I have a few questions that I would appreciate answers to, thank you.
1. How can I query the OCV table corresponding to the DOD?
2. How is the DOD-final calculated, and in which register can it be read?
3. What is the update mode of impedance when the learn status is 6, and is there still an impedance growth limitation?

  • 0
    Prodigy 30 points

    4.In the "registers" page, what does "voltage" represent - the calculated battery voltage value or the OCV voltage read at this time based on the DOD?

  • 0 in reply to zed
    TI__Genius 17555 points

    Hi,

    I am currently looking into this, please allow me sometime.

    Regards,

    Diego

  • 0 in reply to Diego
    Prodigy 30 points

    Hi,Diego

    Thank you for your reply. I look forward to your further response.
    Regards,

    Zed

  • 0 in reply to zed
    TI__Mastermind 29686 points

    Hello Zed,

    Can you clarify what you mean by question #1. 

    #2: DOD Final is an internal gauge parameter and not meant to be used by the end customer. The algorithm calculates this with a discharge simulation so this is not done with a simple equation.

    #3: The gauge will update the Ra table after each qualified discharge. I would recommend reading this document: https://www.ti.com/lit/an/slua364b/slua364b.pdf

    #4. Voltage is the measure voltage of the battery.

    Regards,

    Adrian

  • 0 in reply to Adrian
    Prodigy 30 points

    Hello Adrian,

    Thank you for your response.

    #1: In the document, it is stated that "The gas gauge updates information on the chemical depth of discharge (DOD0) based on open-circuit voltage (OCV) readings when in a relaxed state. This is done for each cell separately. DOD is found by correlating DOD with OCV using a predefined table DOD(OCV,T) stored as reserved data flash parameters." - Where can I find this table DOD(OCV,T)? Is it possible to export it for viewing?

    Adrian said:
     https://www.ti.com/lit/an/slua364b/slua364b.pdf

     

    #3: The documentation indicates that there are updates limitations on impedance when the learn status is  2. However, I don't seem to see any mention of the learn status being equal to 6, are their r-value update limitations the same?

    There is also a question, after testing, I found that every time passing through 11% of the dod grid, the ra impedance table will immediately switch to another table and update all the impedance values of the other table. The data of the impedance values updated are stored in the ram, can this data be read?

    I would greatly appreciate your reply.

     

    Regards,

    Zed

  • 0 in reply to zed
    TI__Mastermind 29686 points

    Hello Zed,

    The predefined DOD(OCV,T) table is not publicly available for the user to see. I can not share these values.

    Yes, you are able to read the Ra table from RAM.

    Regards,

    Adrian

  • 0 in reply to Adrian
    Prodigy 30 points

    Hello Adrian,

    Where can the RAM value be read, in the data flash?Are the update mechanisms for the RAs' resistance values in Learn Status 2 and Learn Status 6 consistent?

    Regards,

    Zed

  • 0 in reply to zed
    TI__Mastermind 29686 points

    Hello Zed, 

    You can use BQStudio to see the address (Subclass ID and offset) for the Ra tables. Updates are consistent with Learn Status 6, since this indicates that impedance track is enabled. Learn status 2, means impedance track is not enabled.

    Regards,

    Adrian

  • 0 in reply to Adrian
    Prodigy 30 points

    Hello Adrian,

    Thanks.In this context, "ram" refers to the data stored in the data flash, or it could refer to something else entirely?

    Regards,

    Zed

  • 0 in reply to zed
    TI__Genius 17555 points

    Hi Zed,

    You are correct.

    Regards,

    Diego