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BQ34Z100-G1: Gas Gauging 'Quit Current' setting when trickle charging?

Allan Engelhardt
Prodigy 50 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ34Z100

Hello,

We have an application with 6S1P NiMH 12000mAh. When charge termination is detected,~100mA is applied. Should we set 'Chg Current Threshold' below the trickle charging rate so that the gas gauge thinks it is still charging while trickle charging? Should 'Quit Current' be above 100mA so that it will go into relaxation mode when trickle charging for OCV readings and Qmax updates?

Sometimes the pack is trickle charging for 2-3 hours past charge termination. If the pack does not enter relaxation mode this long after charge termination, could this have detrimental effects on Qmax and RA tables?

Thanks,

Allan

  • 0
    TI__Guru* 76230 points
    hi Allan
    For our gauges, taper current should be set greater than chg current threshold and the chg current threshold should be greater than quit current.

    So if you when the gauge detects charge termination, the current is 100mA, then your chg current should be something like 70mA and your quit like 30mA or 40mA.

    Even if you continue charging past charge termination, the gauge will see that as an overcharge condition and that will not affect qmax or Ra table. The gauge will use the DOD at EOC which was taken when charge termination occured to calculated qmax. If another DOD0 is taken while at rest that satisifies the dv/dt condition of 4uV/s, then it will use that DOD0 instead of DOD at EOC for qmax calculations. If it is unable to take one, it will use the DOD at EOC and that will give reasonable qmax values.

    I hope this helps and let me know if you have further questions.
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 10 points
    Hi Onyx;
    we apply the bq34z100-g1 for 6S1P, the current sense resistor is 2mohm,we download default srec file before golden learning, the default CC Gain/Delta is 10mohm,when calibrating the current and voltage,the bq management studio remind that the calibration value out of range, what is cause lead to the mistake?
  • 0 in reply to user4331181
    TI__Guru* 76230 points
    I don't believe the bq34z100 is designed to work with a 2mohm sense resistor. The minimum is 5 mohm and that is why you are getting that calibration error

    thanks
    Onyx