For proper BQ34Z100-G1 operation, the battery per cell charging voltage must be specified by the user in Cell Charging Voltage. The default value for this variable is Charging Voltage = 4200 mV. This parameter should be set to the recommended charging voltage for the entire battery stack divided by the number of series cells.
The device detects valid charge termination in one of three ways:
- Current Taper method:
- During two consecutive periods of Current Taper Window, the AverageCurrent() is less than Taper Current AND
- During the same periods, the accumulated change in capacity > 0.25 mAh /Taper Current Window AND
- Voltage() is > Charging Voltage – Charging Taper Voltage. When this occurs, the [CHG] bit of Flags() is cleared. Also, if the [RMFCC] bit of Pack Configuration is set, and RemainingCapacity() is set equal to FullChargeCapacity().
- Delta Temperature (ΔT/Δt) method—For ΔT/Δt, the BQ34Z100-G1 detects an increase in temperature over many seconds. The ΔT/Δt setting is programmable in the temperature step, Delta Temp (0°C – 25.5°C), and the time step, Delta Temp Time (0 s–1000 s). Typical settings for 1°C/minute include 2°C/120 s and 3°C/180 s (default). Longer times may be used for increased slope resolution.
In addition to the ΔT/Δt timer, a holdoff timer starts when the battery is charged at more than Holdoff Current (default is 240 mA), and the temperature is above Holdoff Temp. Until this timer expires, ΔT/Δt detection is suspended. If Current() drops below Holdoff Current or Temperature() below Holdoff Temp, the holdoff timer resets and restarts only when the current and temperature conditions are met again.
- Negative Delta Voltage (–ΔV) method—For negative delta voltage, the BQ34Z100-G1 detects a charge termination when the pack voltage drops during charging by Cell Negative Delta Volt for a period of Cell Negative Delta Time during which time Voltage() must be greater than Cell Negative Qual Volt.
When either condition occurs, the Flags()[CHG] bit is cleared. Also, if the [RMFCC] bit of Pack Configuration is set, and RemainingCapacity() is set equal to FullChargeCapacity().