Make sure you get the most value and use out of your ARYA Q Powered By Drive when you have at least 2 batteries that you can swap between to minimize downtime. Instead of solely relying on the AC or DC power supply to charge a single battery at a time, you should consider purchasing the ARYA Q external battery charger. With the external battery charger, you will have the ability to have one battery installed in the ARYA Q Powered by Drive portable oxygen concentrator, while having a second battery charging separately on the side with the external battery charger. The external battery charger features its own AC power supply, meaning you can plug it into any standard wall outlet to always have a second battery charging. You will never be restricted to charging with the AC or DC power supplies, as the ARYA Q Powered By Drive gives you the ability to charge in 3 quick and convenient methods that suits your needs. The external battery charger is a customer favorite for the simple fact that you can charge one of your extra batteries on the side, externally from your unit, meaning you can always have a battery charging and ready to go when the one you are using runs out.