SLUUA65E april 2014 – june 2023 BQ28Z610
QMax update is enabled when gauging is enabled. This is indicated by the GaugingStatus[QEN] flag. 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 < 4 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. The GaugingStatus[REST] flag is set when a valid OCV reading occurs. If a valid DOD0 (taken at a previous QMax update) is available, then QMax will also be updated when a valid charge termination is detected.
Several flags in GaugingStatus() are helpful to track for QMax update conditions. The [REST] flag indicates an OCV is taken in RELAX mode. The [VOK] flag indicates the last OCV reading is qualified for the QMax update. The [VOK] is set when charge or discharge starts. It will be cleared when the QMax update occurs, when the offset error for a QMax disqualification is met, or when there is a full reset. The [QMax] flag will be toggled when the QMax update occurs. ITStatus2() and ITStatus3() return the QMax and DOD (depth of discharge, corresponding to the OCV reading) data.