BQ28Z610: Qmax Cycle count=0 issue?

Bruce,

please check the Qmax update Criteria as below. please double check If the capacity (SOC) change between suitable battery rest periods is >90 % during the initial cycle.

QMax update is enabled when gauging is enabled. The bq28z610 updates the no-load full capacity
(QMax) when two open circuit voltage (OCV) readings are taken. These OCV readings are taken when
the battery is in a RELAXED state before and after charge or discharge activity. A RELAXED state is
achieved if the battery voltage has a dV/dt of < μV/s. Typically it takes 2 hours in a CHARGED state and
5 hours in a DISCHARGED state to ensure that the dV/dt condition is satisfied. If 5 hours are exceeded, a
reading is taken even if the dV/dt condition was not satisfied. If a valid DOD0 (taken at a previous QMax
update) is available, then QMax is also updated when a valid charge termination is detected. Qmax is not
update if the following occurs:
• Temperature — If Temperature is outside of the range 10°C to 40°C.
• Delta Capacity — If the capacity change between suitable battery rest periods is less than 90 %
during the initial cycle and 37% during field update (2nd and subsequent updates) of qmax.
• Voltage — If CellVoltage2..1 is inside a flat voltage region. (See the Support of Multiple Li-Ion
Chemistries With Impedance Track Gas Gauges Application Report (SLUA372) for the voltage ranges
of other chemistries.) This flat region is different with different chemistry. The GaugingStatus[OCVFR]
flag indicates if the cell voltage is inside this flat region.
• Offset Error — If offset error accumulated during time passed from previous OCV reading exceeds
1% of Design Capacity, update is disqualified. Offset error current is calculated as CC
Deadband/sense resistor value.