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BQ35100: Cr2450 chemical ID

Albin Mathew
Prodigy 30 points
Part Number: BQ35100
Other Parts Discussed in Thread: BQSTUDIO, EV2400

HI,

I am currently using a CR2450 battery for my application. However, I've encountered an issue as the chemical ID for this specific battery is not available in BQ Studio. After researching forums, it has come to my attention that finding a chemical ID for a non-rechargeable battery can be quite challenging.

Since it is a Lithium manganese dioxide battery, I am currently using a similar batteries chemical ID for testing.(like 0500 -UB 1426, 0616 Panasonic CR123A and default chemical id 0x0606). From my testing, I observed that the chemical ID has a relevant impact on finding the State of Health.

Could you please advise on which chemical ID would be better suited for my battery (Panasonic CR2450 -coin cell, 3V, 620 mAh)?

  • 0
    TI__Guru** 104905 points

    Hello Albin,

    Generally for primary cells you must use a chem ID that is already generated, it is not recommended to find a close match using the GPCCEHM tool since the primary batteries tend to have a flat OCV curve for a longer period of time.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    I am using a coin cell for my application, but I couldn't find any coin cell batteries in the chemical ID list. Could you please suggest one?

    If it's not possible, what should I do to gauge the battery?

  • 0 in reply to Albin Mathew
    TI__Guru** 104905 points

    Hello Albin,

    Have you updated your chemistry database with the most recent revision using the chemistry updater?

    https://www.ti.com/tool/GASGAUGECHEM-SW

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    Hello Wyatt,

    I have already updated the database.

    I have two more questions.

    The first one pertains to the golden image. Based on my research, it appears that I cannot update the chemical ID through data flash writing. Therefore, I believe I need to program the Golden Image initially. Could you please share any documents that could assist me in programming the BQ35100 from an external MCU over I2C?

    My second question relates to restoring the default firmware to my gauge. When I issued the 'new battery' command previously, the State of Health (SOH) was reset to 100 percent. However, it is currently set to 0, which is not the expected behavior. I came across some information on forums suggesting that firmware issues might be the cause of this problem. Additionally, when I attempt to write to flash through Advanced commands, the older values do not change. However, the FLASF bit in the control register remains at 0. Could you please provide more clarity on this issue?

    Can you also guide me on how to restore the default firmware on my device?

    I'm also hoping you could share some insights regarding the Chemical ID.

  • 0 in reply to Albin Mathew
    TI__Guru** 104905 points

    Hello Albin,

    Yes that's correct, you must use the EV2400 to make your golden image, this is the file used for production programming. Once you jave the file exported from BQstudio with the correct Chem ID you can upload it following the Gauge Communication app note which shows how to parse the flash stream files.

    The new battery command only resets specific registers relating to battery historical data. You have to upload the SREC from TI.com to fully reset the gauge flash contents to default.

    If you have the wrong Chem ID uploaded the SOH will not report correctly, so the Chem ID should be the first step.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    HI Wyatt,

    Could you share any documents or links that that assist in downloading the default SREC file?.


    I couldn't find a specific coin cell battery in the bq studio list. Since my application is small, I cannot accommodate a large cell. I should use a coin cell battery for my application. Could you please suggest any possible workarounds for this?

  • 0 in reply to Albin Mathew
    TI__Guru** 104905 points

    Hello Albin,

    You must go to the BQ35100 product page and download the firmware, run the installer which should get you the SREC. The SREC can be uploaded in BQStudio using the programming tab.

    There's not a work around for this since OCV is very critical for gauging. I sent you a message to discuss further offline.

    Sincerely,

    Wyatt Keller