Passport includes 2x Energizer Lithium AAA batteries and is specifically designed to work only with lithium AAAs. Passport's battery life indicator is calibrated to Energizer Lithium AAAs.
If using Passport regularly, we recommend rechargeable lithium AAAs, like this option on Amazon. If using rechargeable, constant voltage lithium AAAs, Passport's battery indicator may not be accurate.
Passport currently lasts for 3-4 hours of continuous use. We are working to improve these numbers in future firmware updates!