SLUUCP8 June 2024 BQ41Z50
A QMax update is enabled when gauging is enabled. This is indicated by the GaugingStatus()[QEN] flag. The BQ41Z50 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 two hours in a charged state and five hours in a discharged state to ensure that the dV/dt condition is satisfied. If five hours is 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 the previous QMax update) is available, then QMax will also be updated when a valid charge termination is detected.
The flag is cleared at the exit of a relaxed state. A QMax update is disqualified under the following conditions:
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 clears 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. GaugeStatus3() returns the QMax and DOD (depth of discharge, corresponding to the OCV reading) data.
The BQ41Z50 device includes a check in which, during discharge, there must be a minimum change in Voltage() programmed in Min Delta Voltage. There is also a maximum change set in Max Delta Voltage.
Class | Subclass | Name | Format | Size in Bytes | Min Value | Max Value | Default Value | Unit |
---|---|---|---|---|---|---|---|---|
Gas Gauging | DZT Cfg | Min Delta Voltage | Int | 2 | –32768 | 32767 | 0 | mV |
Class | Subclass | Name | Format | Min Value | Max Value | Default Value | Unit |
---|---|---|---|---|---|---|---|
Gas Gauging | DZT Cfg | Max Delta Voltage | I2 | –32768 | 32767 | 200 | mV |