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BQ30Z554-R1: Valid Charge Termination questions

Jimmy Zhou
Prodigy 120 points
Part Number: BQ30Z554-R1
Other Parts Discussed in Thread: BQ30Z55

Hi Guys,

My question is regarding the bq30z55 V0.36 device Valid Charge Termination condition? 

As TRM file mention, (Charging AND AverageCurrent() continuous < Charge Term Taper Current AND Voltage() > ChargingVoltage()/Number of Cells + Charge Term Voltage AND Δcharge > Taper Charge) for two consecutive 40-s periods.

regarding the two consecutive 40 -S periods, how to understand this condition? I think need 80S to meet the condition, but during my test, the device RSOC drop to 100% about 57S, not 80S.

Can you help to explain? Thanks.

Jimmy,

Best regards,

  • 0
    TI__Mastermind 42535 points

    Hi Jimmy,

    The 2 40s periods should be back to back. That does mean a total of 80s. The period of counting begins from the time that the internal voltage read on the stack is greater than the threshold.

  • 0 in reply to Batt
    Prodigy 120 points

    Hi Batt,

    Thanks for you reply.

    But for my, it hard to understand the counting begins from the time that the internal voltage read on the stack is greater than the threshold.

    1. Because in my test data, after voltage greater than the threshold and keep long time, and the met Valid Charge Termination when charge current below taper current and keep 57 seconds.

    2. How to understand Δcharge > .25 mAH? Why set 0.25 mAH? 

    (Charging AND AverageCurrent() continuous < Charge Term Taper Current AND Maximum cell voltage in Voltages() + Charge Term Voltage > ChargingVoltage()/Number of Cells AND Δcharge > .25 mAH) for two consecutive 40-s periods.

    Jimmy,

    thanks.

  • 0 in reply to Jimmy Zhou
    TI__Mastermind 42535 points

    Hi Jimmy,

    1. Please log the data at a 1s interval. Once the voltage is higher, the first case for the window begins. Secondly once the current drops below taper current value the second condition is satifised and the timer starts. Your RSOC thresholds might also be affected by smoothing  and other bits like RSOC_HOLD.

    2. We need a positive charge delta for charge termination. We can have both a chg I and high voltage meeting termination conditions without  a positive increase in chg. So to make sure that we are absolutely in charge mode, we set a positive chg delta for the charge value.