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BQ25306: Whether the output voltage of the BQ25306 increases when the battery is in the protected state

Part Number: BQ25306

Hi TI Teams,

We have one question about the output voltage of the BQ25306, that is, whether the output voltage of the BQ25306 increases when the battery is in the protected state.

The battery that we used is a 7.4V lithium battery pack with a protection plate. When the battery pack is overdischarged, the overdischarge protection function will take effect, that making the output current of the battery is 0. At this time, if we want to activate the battery pack again, we need to add a voltage of no less than 7V to the battery pack, otherwise the output current will be 0A all the time.

We can learned from the datasheet of BQ25306 that the short-circuit detection will output a voltage of about 2V, but the detection voltage cannot rises to a certain value (7V) which result the battery pack cannot be activated. When the adapter is insert in, we detected that the output voltage of BQ25306 to the battery is about 2V, the battery pack cannot be activated and charged. Is there any way to solve this problem?

The schematic is as below:

The Battery Charging Profile on the datasheet.

Thanks,

Kind Regards

  • Hello,

    Is the pack holding the voltage of the battery at 2 V? If the battery is fixed at 2 V it will apply IBAT_SHORT until precharge is entered. If the pack is holding the voltage at 2 V however our charger will treat it as a 2V battery. Do you intend to over discharge the battery regularly? Is there any circuit you have to "wake" up the battery?

    Regards,

    Mike Emanuel

  • HI Mike 

    Our battery packs will disconnect the battry form the circuit when OVER discharge is comming. in this case , the battery is equivalent to open load. At the same time ,the BQ25306's VBAT is only 2.0V and no current .(The voltage of VBAT is 2.0V when the no battery is connected). and there is a same case in the TI E2E  e2e.ti.com/.../bq25306-bq25306-cann-t-charge

  • HI Mike 

    Our battery packs will disconnect the battry form the circuit when OVER discharge is comming. in this case , the battery is equivalent to open load. At the same time ,the BQ25306's VBAT is only 2.0V and no current .(The voltage of VBAT is 2.0V when the no battery is connected). and there is a same case in the TI E2E  e2e.ti.com/.../bq25306-bq25306-cann-t-charge

  • Hello,

    Can you confirm your setup? What is the input voltage? Do you have a load on PMID? If so how much? The post linked here shows that the trickle charge current is sensed across Q1, and if loading PMID that will cause the behavior shown.

    Also, what is the STAT pin doing?

    Regards,

    Mike Emanuel