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BQ25606: charging continues even after battery is charged

Bart
Expert 6470 points
Part Number: BQ25606


Dear Team,

we have the following problem with bq25606:

When the temperature of the battery gets to T3-T5 range, the charging voltage gets reduced to 4.1V but at the same time the condition to stop charging is not followed (charging process continues when current drops to 5% of nominal value, which should not be happening).

In other words, when the battery is hot, the charging voltage drops to 4.1V, the battery gets charged and charging current drops to almost zero, but the charging is not stopped.

How can we overcome this behavior? This is a finished project.

Thanks for your help,
Regards, Bartosz



  • 0
    TI__Mastermind 25800 points

    Hey Bartosz, 

    The datasheet for the charger needs to be updated. Charging does not terminate in either TCOOL (T1-T2) or TWARM (T3-T5).

    This needs to be updated in our datasheet.

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    TI__Expert 6470 points
    Hi Joel,

    our customer is using 4.2V batteries. If we understand correcly, when the battery is warm it will be charged with 4.05V voltage until infinity, or when the timer stops it. The question is - Is that safe? This will lead also to the error indication, is that correct?

    Regards,
    Bartosz
  • 0 in reply to Bart
    TI__Mastermind 25800 points

    Hey Bartosz,

    I want to dispel the concern of safety. In TWARM, the battery regulation voltage drops to 4.05V, yes. 

    However, because the regulation point is lower than the battery voltage, there will be no charge current into the battery. The only thing of note here is that there will be no indication of termination (STAT pin low). If the battery is above that threshold by 103%, there will be, correctly so, a BATOVP fault. 

    So in summary, if the JEITA (TS temperature profile) is used on our charger, if the TS impedance goes enters TWARM, then charging will not terminate and there may possibly be a BATOVP event, while you stay in TWARM. 

    However, the customer is not required to use the TS pin for JEITA battery temperature protection.

    Regards,

    Joel H