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BQ27421-G1: Cannot find Chemistry tab in bqStudio

Chase Jeong
Mastermind 7555 points
Part Number: BQ27421-G1
Other Parts Discussed in Thread: BQSTUDIO, BQ40Z50, GPCCHEM, BQ27220, BQ27Z746, BQ27Z558, GPCCEDV

Tool/software:

Deat TI experts,

My customer considers BQ27421-G1 for their new project.

First I wanted to know that their cell is tested by TI and already registered chemistry ID.

But I cannot find Chemistry tab if I select BQ27421-G1 in bqStudio.

On the other hand, I can find Chemistry tab if I select BQ40Z50 instead.

Am I missing something?

- Screenshot of BQ27421-G1 : No Chemistry tab.

- Screenshot of BQ40Z50 : Chemistry tab exists.

Best regards,

Chase

  • 0
    TI__Mastermind 24931 points

    Hello Chase, 

    The BQ27421-G1 is a ROM gauge not a Flash gauge. One of the things that comes with the ROM gauges is that you cannot program whatever chemID onto the gauge, rather you are limited to only the pre programmed chemID (see table below). If you wished to program your own custom chemID onto the gauge or a chemID different than the preprogrammed chemID, then you would need to use a different gauge (one of the Flash gauges).  

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Mastermind 7555 points

    Dear Robert,

    Thank you for your support.

    1. You mean that BQ27421-G1A can support only LiCoO2 battery which max voltage is 4.2V?

    And If I use other cells then I should choose another fuel gauge which is a Flash gauge?

    2. What If I connect Li-Polymer cell to BQ27421-G1A? Don't you guarantee the accuracy of gauging?

    3. Could you recommend Flash gauge for Li-Polymer battery? Simplest and smallest would be the best for my customer.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    Mastermind 7555 points

    Dear Robert,

    Thank you for your support.

    1. You mean that BQ27421-G1A can support only LiCoO2 battery which max voltage is 4.2V?

    And If I use other cells then I should choose another fuel gauge which is a Flash gauge?

    2. What If I connect Li-Polymer cell to BQ27421-G1A? Don't you guarantee the accuracy of gauging?

    3. Does BQ27421 series originally made for only specific cells?

    4. Could you recommend Flash gauge for Li-Polymer battery? Simplest and smallest would be the best for my customer.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Mastermind 24931 points

    Hello Chase, 

    If you want to determine whether a given cell (no matter the chemistry) will work for a given chemID, I recommend to use the GPCCHEM tool. For a good match you should use a chemID with a DoD% error less than 3%. 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Mastermind 7555 points

    Dear Robert,

    Thank you for your support.

    Yes, I know that I should use GPCCHEM tool to find right chemID. But You said that BQ27421-G1A already have fixed chemID and it never changes because it is ROM gauge.

    Please give me the answer what I already asked below, then I can choose right fuel gauge with my customer.

    1. You mean that BQ27421-G1A can support only LiCoO2 battery which max voltage is 4.2V?

    And If I use other cells then I should choose another fuel gauge which is a Flash gauge?

    2. What If I connect Li-Polymer cell to BQ27421-G1A? Don't you guarantee the accuracy of gauging?

    3. Does BQ27421 series originally made for only specific cells?

    4. Could you recommend Flash gauge for Li-Polymer battery? Simplest and smallest would be the best for my customer.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Mastermind 24931 points

    Hello Chase, 

    1. No. The preprogrammed chemID can support different chemistries. The reason I was suggesting to use the GPCCHEM tool is because it gives you a report for your cells and tells you what the DoD% error is for the chemID that the BQ27421-G1 supports. The main thing to look at when choosing a chemID is the DoD % error between your cells and the chemID, not the chemistry. A good match is considered to have a DoD % error less than 3%. 
    2. Again, we cannot guarantee the accuracy of the gauge with your cell until you determine that the cell you are using is a good match for the chemID on the BQ27421-G1 fuel gauge (DoD % error less than 3%). 
    3. The BQ27421 has less cells that it will work with compared to our flash gauges, given that you cannot program just any chemID onto the BQ27421 gauge. 
    4. A flash gauge you could use for a 1s application is the BQ27z558 (this gauge does not have protections) or the BQ27z746 (this gauge does have protections), depending on the system requirements. 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Mastermind 7555 points

    Dear Robert,

    Thank you for your support.

    My customer asked about BQ27220 which has CEDV algorithm.

    (BQ27Z558 and BQ27Z746 need larger PCB space comared to BQ27220, they do not have enough PCB space.)

    Do you think that is it okay to use BQ27220 for 1-cell Li-polymer battery which capacity is 410mAh?

    Maybe they will use wifi module and maximum current consumption would be 300mA during 5~10 minutes.

    Please also check that you have a history of testing with the battery EB-BR945ABY.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Mastermind 24931 points

    Hello Chase, 

    The BQ27220 is a CEDV gauge and does not use custom chemIDs. You can refer to the Chemistry tab in bqStudio to see all of the chemistries we have characterized. 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Mastermind 7555 points

    Dear Robert,

    Thank you for your support.

    Yes I Know that CEDV gauge does not use customer chemIDs. Instead I have to use GPCCEDV tool.

    Just I want to know that BQ27220 is suitable for Li-polymer 410mAh battery.

    And one more request, Do you have any comparison data between Impedance track algorithm and CEDV algorithm including pros and cons of each algorithm?

    With that document, I cam make a decision with my customer which is proper solution.

    Please check this issue. Thanks.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Mastermind 24931 points

    Hello Chase, 

    Please refer to this document on Battery Gauging Algorithm Comparison. 

    Regards, 

    Robert.