The battery is indispensable for a portable oxygen concentrator. Thanks to the battery you are free to go wherever you want. The Inogen One G5 has an unprecedented battery run time: with this lightweight 8 cell battery the concentrator only weighs 2.2 kg and you can still use it for up to 6.5 hours without recharging (complete battery run time table below). Despite the battery's great autonomy, there are situations where a second battery might come in handy, such as during a long-haul flight. For this you have two options: the standard 8 cell battery (BA-500), or a double 16 cell battery (BA-516). This 8 cell battery is lighter, but it has a shorter run time. Also keep in mind that every higher oxygen setting will decrease your battery run time.