The Inogen One G5 Single Battery is a great power source to give you independence and mobility for trips or other activities. This rechargeable lithium-ion single battery provides up to 6.5 hours at a flow setting of 2 when fully charged. The Single Battery is small enough to easily fit in a backpack, accessory bag, or purse. It can be charged with the G5 External Battery Charger or with the Inogen G5 when it is connected to an AC or DC power supply. A fully depleted battery can be charged in under 3 hours.