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BQ35100: Programming Battery Chemistry

Derrick Andreassi
Prodigy 55 points
Part Number: BQ35100
Other Parts Discussed in Thread: BQSTUDIO

Is it possible to change the battery chemistry ID without the interface adapter? We will not be using one for our application and need to change the chemistry ID using the I2C protocol. Based on my reading so far, it looks like the SOH mode only works with Li MnO2 batteries? If we only desire to use this mode does it matter what chem ID is in the device. Also, it looked like the Accumulation mode was chemistry independent. In the end, is it necessary to change the chemistry ID?

Best,

Derrick

  • 0
    TI__Genius 10370 points

    Derrick,

    1) Accumulation mode the chemID does not matter. 

    2) SOH mode is intended for MnO2 cells because those cells as they get depleted voltage decreases.Li-SOCl2 cells do not have this same votlage profile.

    3) To upgrade a gauge via I2C we offer what we call a .bq.fs file. This is an I2C iterable file that just lists the command to send to upgrade a gauge. It can be exported via the "Golden image" plug-in

    Thanks,

    Eric Vos


    7484.Flash Stream File Format.pdf

  • 0 in reply to Vos
    Prodigy 55 points

    Eric,

    Thank you for this. The more and more I read into this device it seems like the best mode for our application is the SOH mode. We will be using the LiMnO2 battery. In that case, will we need to update the battery chemistry or because we are just measuring voltage and temperature does it not matter?

    With that being said, what parameters in the DF would you recommend updating that are specific to our battery to help get the most accurate SOH calculations?

    Thank you,

    Derrick

  • 0 in reply to Derrick Andreassi
    TI__Genius 10370 points

    Derrick,

    The main thing you will need to update is the chemID. You should use bqStudio chemistry plug-in to select the correct ID from the list. The other parameters you want to update are

    1) Termination Voltage - Empty point (normally 2V)

    2) Max Load - This is multiplied by Ra table to see what your estimated loaded voltage is to compare against the chemID for SOH in combination with TermV

    3) SOH max delta - Amount SOH can change when device is woken up

    SOH mode does only use V and T. 

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 55 points

    Eric,

    This cycles back to my original question. We are trying to use our uC for all I2C communication. Our finished product will not have a I2C connector to use the bqStudio. So is it possible to change the chemID without using the bqStudio?

    Could another option be to get the necessary adaptor, use bqStudio, generate that file, and program our uC to write that file when a new battery is inserted. We are trying to avoid this because we would basically use it once to generate a single file and never again.

    -Derrick

  • 0 in reply to Derrick Andreassi
    TI__Genius 10370 points

    Derrick,

    Yes the best option is to get bqStudio on a single device (blue wire to i2c or EVM), program in the ChemID, then export the "golden .fs file" to be programmed in the your uC.

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 55 points

    Eric,

    Another question. If we plan on only using the SOH mode for our application, would we need to include the circuitry around SRN and SRP (sense resistor and caps)?

    -Derrick

  • 0 in reply to Derrick Andreassi
    TI__Genius 10370 points

    Derrick,

    No if you are only using the SOH mode you do not need the SRN/SRP pin circuitry. 

    Thanks,

    Eric Vos