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BQ78350: BQ78350

dj kang
Prodigy 10 points
Part Number: BQ78350
Other Parts Discussed in Thread: BQ76940, , BQSTUDIO

Tool/software:

hello, dear anyone......

I have configured a BQ78350 + BQ76940 13S circuit.
The application is for an E-BIKE, and it uses a 13S battery.

I have the following questions:

  1. I intentionally triggered an over-discharge condition.
    Recovery occurs when charging is detected.
    However, when the battery is at 100% state of charge, charging is not detected.
    At 99% state of charge, recovery works.
    If the user charges the battery to 100% and then immediately triggers over-discharge protection,
    how can recovery be implemented in this case?
    Is it possible to configure this using the Data Memory settings in BQStudio?

  2. I set the over-discharge protection to 20A.
    When the load (E-BIKE) is connected via a connector, a spark occurs due to inrush current,
    and the DISCHARGE FET is immediately turned off.
    The inrush current is approximately 32A (360μs).
    It is not certain whether the FET is being shut off due to the inrush current.
    This situation also tends to occur when the battery is near 100% charge (i.e., higher voltage),
    but does not occur when the battery is around 50% charge.
    Please recommend a solution that does not involve using additional circuit components (such as inductors or varistors).

Anyone, any response, please advise

best regards.
  • 0
    TI__Guru 60916 points

    #1: You would have to apply a current that exceeds the charging current threshold. This would require a charger that can increase the voltage temporarily if the cells will not draw enough current at 100% SOC.

    #2: If this is due to the HW protector (AOLD or ASCD) then you can try to extend both the time and the current threshold. See TRM, 3.6.1 and 3.6.2. The default values are very aggressive so I recommend trying longer delays and higher currents (voltages over the sense resistor).

  • 0 in reply to Dominik Hartl11
    Prodigy 10 points

    The charger voltage is fixed,
    The charger cannot be changed.
    Is there any other way in this case?

    I would also like to consider adding parts(H/W COMPONENT).
    Thank you for your reply,
    We look forward to hearing from you further.

  • 0 in reply to dj kang
    TI__Guru 60916 points

    You'd have to change your design so that the gauge can detect a charge for #1 or you could design your system to allow this condition (VAUXR = 1):

    "[SafetyStatus()[OCD] = 1 AND Protection Configuration:VAUXR = 1 Current() continuous ≥ OCD:Recovery Threshold for OCD:Recovery Delay time OR VAUXVoltage() ≥ Power:Charger Present Threshold"