The Inogen One G4 (4 Cell) Battery provides oxygen users with the freedom to travel with peace of mind. Charge your Single Battery before your trip and you’ll be able to supply your portable oxygen concentrator with up to 3 hours of battery life for the long journey ahead. This battery also has an indicator on one side that will tell you what percentage the battery is charged to, so you don’t have to put it in the machine to see if it is fully charged. With the quick release button, it’s a fast and easy task to switch out your rechargeable batteries whenever you need to. Be sure to give your battery at least 3 hours to reach 100% maximum charge.