The UltrAspire 18650 Battery has 3400 MaH and is programmed for low amperage output to ensure your Lumen has the optimal power source for the best performance on the road or trail. Single 18650 Rechargeable Battery Size: ;=18.1-18.55mm H=65.3 Rating Voltage: 3.7V Capacity: 4.2V-4.3V Charging Mode: C.C/C.V. Charging Method: Standard Charging 0.2C Charging Time: Standard Charging 4-6Hours (in lighting unit) (2-3hours on charger) End of Discharge Voltage: 2.75V Overcharge Voltage: 4.2V-4.3V/cell Over Discharge Cut Off Voltage: 2.5V-4.5V/cell Over Current: 2.5-5.0A Short Circuit: Recover after removing the short circuit - Load Operating Temperature: Charging: 0~45, Discharging:-20~+60, Storage:-5~+35 Cycle Time: 500 cycle