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BQ20Z95: bq20z95, COV flag do not get cleared

user 1234
Prodigy 185 points

Part Number: BQ20Z95

I have a bq20z95 board. Once I fully charge it to 12.6V, after that COV flag gets set as expected.

Problem is after that COV flag dont get reset even if discharged.

1. image 1, shows COV flag get set after fully charge & CHG flag is reset. This is OK

2. in image 2, even after putting battery on dishcarge,  COV flag dont get reset, while CHG flag in on again. this is I dont understand

3. image 3, shows afetr that battery put to charge, COV flag always set & CHG flag is off.

4. attached find gg image also1425.Desktop.zip

  • 0
    TI__Guru* 76230 points
    Hi,
    Why are you charging the battery to COV condition? The voltage needs to go below the COV threshold for the COV flag to clear. You have your threshold set to 4000 and your cell voltages are still higher than 4000
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 185 points
    But as you can see in second image I start discharging first, shouldn't it clear COV flag & then I try to charge it again.
    But now bq20z95 dont let it charge.
    This could create problem in field, suppose once battery is fully charged & then user discharged it little bit & again put to charge, bq20z95 will never let it charge again unless falls below 4000mV/cell
  • 0 in reply to user 1234
    TI__Guru* 76230 points
    again i have to emphasize that charging the battery to an overvoltage condition is not the way to go. The COV is not supposed to be triggered each time you charge. set your COV threshold voltage higher than your charging voltage to avoid that flag triggering.
    To address the charging question, if the voltage of the cell doesn't go below the COV clear voltage, you will be unable to charge the cell.

    thanks
    Onyx