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BQ27742-G1: BQ27742-G1 not working after battery disconnect

Mitul Tank7
Prodigy 120 points
Part Number: BQ27742-G1

Hello Team,

I have a problem with the bq27742-g1 fuel gauge.

As suggested in Forum, to enable bq27742-g1 fuel gauge sort the CELL+ & PACK+ terminals together for a moment, after sorting that both terminals fuel gauge is working fine
but after disconnected a battery from the system BQ27742-G1 fuel gauge is not worked, every time gauge is working after sorting the CELL+ & PACK+ terminals.

What should I do to working it permanently after battery disconnect?

Thanks in advance,

Mitul Tank

  • 0
    TI__Guru 62386 points
    If you disconnect the cell (= the Vbat pin is 0V while Vpwr is still up) and no charger is detected, the gauge will automatically enter analog shutdown mode (see 7.4.1.3 in the data sheet).

    The gauge is intended for a pack application where the battery is never disconnected. What powers you system when you disconnect the battery? You can also wake up the gauge by applying a charging current after your reconnect the battery.
  • 0 in reply to Dominik Hartl11
    Prodigy 120 points
    Hello Dominik,

    Thank you very much for quick reply

    We have listed below query

    1. Can we connect High value resistor (64K ohm) in between Pack+ & CELL+ permanent inside the system?

    2. what is the drawback if we connect resistor in series between Pack+ & CELL+?

    3. Can you suggest us any other way to sort Pack+ & CELL+ for a moment.

    Thank & Regards,
    Mitul Tank
  • 0 in reply to Mitul Tank7
    TI__Guru 62386 points
    1. If you do this, please make sure that the PACK+ pin will fall below the under voltage threshold if your battery gets discharged below this threshold. Otherwise the under voltage protection won't work. The same applies to over voltage protection.

    2. You potentially disable the protection (depending on your overall design)

    3. You don't have to short CELL+ and PACK+. You just have to apply a voltage on PACK+ that is within the operating range of the battery (e.g. +3.3V).