SLUUCH2 March 2021 BQ40Z50-R2
The Fast Qmax update conditions are very similar to the QMax update conditions with the following differences:
The differences in requirements allow the Fast Qmax feature to have a QMax update at the end of discharge (given one OCV reading is already available and discharge below 10% RSOC) without a longer relax time after a discharge event. Typically, it can take up to 5 hours in a DISCHARGE state to ensure the dV/dt < 4 µV/s condition is satisfied. The temperature, delta capacity, voltage, and offset error requirements for QMax update are still required for the Fast Qmax update.
This feature is particularly useful for reducing production QMax learning cycle time or for an application that is mostly in charge or discharge stage with infrequent relaxation. Setting IT Gauging Configuration[FAST_QMAX_LRN] = 1 enables Fast Qmax during production learning only (that is, Update Status = 6). When setting IT Gauging Configuration[FAST_QMAX_FLD] = 1, Fast Qmax is enabled when Impedance Track is enabled and Update Status ≥ 6.