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Original question:

BQ24005 not working - parts being damaged after power up

BQ24005: BQ24005

Dickie Cheung
Prodigy 30 points
Part Number: BQ24005


Hello,

I am using the BQ24005 to charge a 2-cell 18650 2200mAH Lithium-ion battery. 

Sometimes, the battery can be charged normally when DC 9V is inputted.

Sometimes when DC 9V is inputted, the battery is charged for 1~2 seconds (STAT1 LED on). Then, the charging stops (STAT1 LED off). The charging will not start again.

But, if the DC 9V is unplugged and plugged again several times, the charging can start normally. 

Are there any idea what is the problem going on ?

Thank forward for assistance.

Best rgds,

Dickie Cheung

  • 0
    TI__Mastermind 19195 points

    Hi Dickie,

    APG/Therm invalid and thermal shutdown both lead to STAT1 off -- could be either of these. What is voltage on the APG/Therm pin when this occurs? Does this happen at all battery voltages?

    What is STAT2 doing during this time?

    Please upload the schematic here if possible.

    Best,

  • 0 in reply to Nick Brylski
    Prodigy 30 points

    Hello Nick,

    Thank you for your reply.

    I tried to charge a fully discharge battery this morning. The battery voltage is 0V. It is OK this time. The APG/Therm pin voltage is 0.98V. I will try to repeat the problem and give you the APG/Therm pin voltage. 

    I am not sure the battery voltages when this happen. Because I did not monitor the battery voltage. Every time when I see the system shut down as the battery is drained off, I will re-charge the battery. So, I think the battery voltage should be very low. 

    The STAT2 is also OFF during the problem occurred.

    Please find the schematic of the power part.

    Best regards,

    Dickie Cheung

  • 0 in reply to Dickie Cheung
    TI__Mastermind 19195 points

    Dickie,

    There will be high temperatures when charging battery so deeply discharged. Power dissipated by linear charger is (Vin - Vbat) * current. 0V is much further discharge than we normally see for li-ion, 3V / cell is usual cutoff.

    Best,

  • 0 in reply to Nick Brylski
    TI__Mastermind 19195 points

    Hi Dickie,

    Any updates here?

    Thanks,

  • 0 in reply to Nick Brylski
    Prodigy 30 points

    Hello Nick,

    Before, I was using a 9V DC adaptor to charge. But, it seems the voltage drop on the adaptor socket and the PCB traces make the voltage to the charger IC below the operating voltage. 

    I am now using a 9.5V DC adaptor to charge. So far, no problem now. 

    Thanks you for your help.

    Best regards,

    Dickie Cheung