Tip: Are you going to travel by plane? Then it is recommended – or even required – to bring with you one or more extra batteries on board.
The Inogen One G4 doesn't have the long battery runtime of the G2 and G3. With this 8 cell battery, you can increase your mobility dramatically.
With the concentrator, you can charge one battery at a time. To charge multiple batteries, or separately from the concentrator, you can use the external battery charger.