SLUUC54C February 2020 – March 2024 BQ27Z558 , BQ27Z561 , BQ27Z561-R2
The BQ27Z561-R2 measures individual cell voltages, pack voltage, temperature, and current. When at rest and GaugingStatus[REST] is set or when cell impedance is updated, the Impedance Track capacity calculation determines battery state-of-charge from DOD and temperature. The BQ27Z561-R2 measures charge and discharge activity by integrating the voltage across a small-value series sense resistor (1 mΩ typ.) between the negative terminal of the cell stack and the negative terminal of the battery pack. The battery state-of-charge is subsequently adjusted during load or charger application, using the integrated charge passed through the battery.
The device is capable of supporting a maximum battery pack capacity of 32 Ah. See the Theory and Implementation of Impedance Track? Battery Fuel-Gauging Algorithm in the bq20zxx Product Family Application Report (SLUA364) for further details of the Impedance Track calculations.
The default for Impedance Track gauging is off. To enable the gauging function, set Manufacturing Status[GAUGE_EN] = 1. The gauging function will be enabled after a reset or a seal command is set. Alternatively, the MAC command Gauging() can be used to turn on and off the gauging function. Gauging() takes an immediate effect and the [GAUGE_EN] is also updated accordingly.
The ITStatus1(), ITStatus2(), and ITStatus3() commands return various gauging related information, which is useful to verify learned cell data was updated correctly, as well as problem analyses.