SLUUC54C February 2020 – March 2024 BQ27Z558 , BQ27Z561 , BQ27Z561-R2
The BQ27Z561-R2 TURBO Mode 3.0 helps the system to adjust the power level by providing information about maximum power, depending on the battery state-of-charge, temperature, and present battery impedance. The gauge informs the system about the power level above which would cause the system voltage to drop below termination after the 10-s pulse, which is called the sustained peak power (SPP). In addition, the gauge also reports the maximum power for the combined 10-s and 10-ms pulses called the maximum peak power (MPP).
A system with TURBO Mode 3.0 applies short high-power load pulses (for example, up to 4 C-rate for as long as 10 ms). In addition, 10-s load pulses of 2 C-rate can occur in some cases prior to 10-ms pulses, resulting in a combined effect during the turbo boost operation. The 10-s pulse support is new in TURBO Mode 3.0. Additionally, TURBO Mode 3.0 provides Rhf effective and Vload parameters for the host to use to make power-level decisions.
These high-power pulses may drop down battery voltage. If the battery voltage drops below Shutdown Voltage, the system will shut down. To avoid shutting down the system during turbo boost operation, the system should never apply a pulse that would cause the system voltage to drop below the termination voltage (or exceed the recommended current threshold) that could result in a shutdown, reducing the total available run time.
The SPP is computed using a 10-s effective resistance that is temperature- and DOD-dependent. The computation of MPP uses the high-frequency resistance along with the 10-s effective resistance. Both of these resistances are chemistry-specific. In addition, the Pack Resistance and System Resistance are important parameters used in the calculation of these two powers. The computed TURBO mode currents, the sustained peak current, and the maximum peak current are capped to their respective maximum discharge rates. Depending on how often the system polls the peak power data and how fast the system can switch to a lower power mode, it is possible to exceed the reported peak power levels during the present power consumption. To avoid any system shutdown, the gauge provides a Reserve Energy % setting that can serve as a buffer to ensure there is available energy at the present average discharge rate. These calculations occur on the cell level using Term Min Cell V, on the pack level using Term Voltage, and on the system level using Min System Voltage, Pack Resistance, and System Resistance with the most conservative prediction reported.
Min System Voltage should be set lower than Term Voltage.
| Class | Subclass | Name | Type | Min | Max | Default | Unit | Description |
|---|---|---|---|---|---|---|---|---|
| Gas Gauging | Turbo Cfg | Min System Voltage | I2 | 0 | 32567 | 3000 | mV | The minimum voltage at the pack terminal to be used for TURBO mode. |
| Gas Gauging | Turbo Cfg | Ten Second Max C Rate | I1 | 0 | 1127 | –20 | .1 hr | A 10-second load value to be used by the TURBO Mode calculation |
| Gas Gauging | Turbo Cfg | Ten Millisecond Max C Rate | I2 | 0 | –127 | –40 | .1 hr | A 10-ms load value to be used by the TURBO Mode calculation |
| Gas Gauging | Turbo Cfg | High Frequency Resistance | I2 | 0 | 32767 | 36 | mΩ | The high-frequency resistance related to the specific cell chemistry and pack configuration |
| Gas Gauging | Turbo Cfg | Reserve Energy % | U1 | 0 | 100 | 0 | % | This sets the % of remaining energy at the present average discharge rate (as defined in Load Select) until the maximum peak power reaches the value reported by MaxPeakPower(). |
| Gas Gauging | Turbo Cfg | Turbo Adjustment Factor | U1 | 0 | 255 | 100 | — | This is a resistance correction factor that, if used, would be a one-time adjustment the user computes from a 10-s pulse test. |