The Iridium 3.7V 2200mAh Rechargeable Li-ion Battery. Model: (BAT20801)
Features:Capacity: 2200 mAhType: 3.7 V Lithium IonTalk time: 4.0 hoursStandby time: 30 hoursCharge time: Via handset 3 hours is typical 90% capacity at 25°C (77°F)Charge Conditions: Only between 0°C (32°F) and 40°C (104°F).