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BQ77915: BQ77915

Gururaj Talewad
Prodigy 50 points
Part Number: BQ77915

When low side MOSFETs are OFF, why pack voltage in not zero when pack is open circuit. any suggestions to make output voltage zero when read with multimeter.

  • 0
    TI__Guru* 81034 points

    Hi Gururaj,

    If you want to read zero with a multimeter, you would need to detect that the FET outputs are low and then short the pack terminals together. The device pulls down on CHG when off.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    Hello Matt,

    You are correct once we short pack terminals voltage is zero. But how a service person will come to know where BMS is in on state or off state. when BMS is inside the battery and packed. Short terminal is not safe options to check status of BMS. Please can you suggest any extra circuit to make output voltage zero when DSG mosfet is off.

  • 0 in reply to Gururaj Talewad
    TI__Guru* 81034 points

    Maybe applying some type of load to the PACK when making the measurement (like 100k or so) might be helpful for this purpose. I think this will be a common issue for many batteries with protection FETs since PACK- is disconnected from the cells.

    Best regards,

    Matt