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BQ20Z95: Please review the schematic

Chase Jeong
Mastermind 7345 points

Part Number: BQ20Z95

Hello TI experts,

my customer is in mass production of battery pack using BQ20Z95 few years ago,

recently they found some problems.

- gauging suddenly falls from 50% to 25%

- cannot wake up after cut off protection (no voltage detection from the pack)

- cannot charge even detect the very low voltage

so could you review the schematic if there is anything wrong?

and i also attach the cell specification for your convenience.

- Samsung SDI ICP544382A (3.85V 2800mAh)

- 3S1P

Please check this issues. Thanks.

Best regards,

Chase

C3(3S1P)_140416.pdf

  • 0
    TI__Guru** 105590 points

    Hello Chase,

    The SOC would be a configuration issue. I think you already have a thread open for that issue.

    If the secondary protections blow the fuse, the gauge may not sense the voltage anymore.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Mastermind 7345 points

    Hello Wyatt,

    Yes I already opened another thread before.

    at that time I just thought that there was something wrong in learning process.

    so recently i started doing learning cycle again for accurate GG file, but problems appear continuously.

    main problem is i discharge the battery and rest over 5 hours, i can detect battery voltage very low, but i cannot charge the battery again for 2nd learning cycle.

    even i attach the battery but no loads to battery. so i though that there is probably something wrong with the schematic.

    anyway yes, I agree with your saying. there is something wrong with SOC calculation.

    because 50% battery and 25% battery both turn to green led immediately when attach to charger.

    and the real voltage measured using multimeter are almost same.

    could you give me some advice for this problem? it will be the best if we don't do learning cycle again, cause we have so many problems with learning cycle.

    you know, there is many documents, separated information, even i cannot find some information because this is too old device. i refered some new device.

    please check this issue. Thanks.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Guru** 105590 points

    Hello Chase,

    I don't think this is a hardware/layout issue if the main issue is SOC jump.

    We can continue support on the other thread: e2e.ti.com/.../967198

    Sincerely,

    Wyatt Keller