Apple's upcoming iPhone Duo features a dual-battery design, with battery life varying by screen usage. On the larger 7.6-inch inner display, video playback lasts up to 31 hours, while the 5.4-inch outer display extends it to 44 hours. Apple's typical use metric, mixing both screens, delivers up to 24 hours, matching the iPhone 18 Pro's rating.

The iPhone Duo's dual batteries are managed as a single unit by iOS, optimizing capacity within the foldable frame. Apple highlights the efficiency of the C2 modem and A20 Pro chip, alongside the eSIM-only design, to maximize endurance. Charging supports 60W USB-C for a 50% charge in about 20 minutes, plus MagSafe and Qi2 wireless up to 25W.

Comparing models, the iPhone 18 Pro Max leads with up to 45 hours of video playback, while the Duo's 31-hour inner screen result trails slightly. The outer screen's 44 hours nearly matches the Pro Max, showcasing the benefit of using the compact display for extended sessions.

Preorders for the iPhone Duo open on October 16, with launch following October 23. The device was unveiled at Apple's September event, positioning it as a versatile foldable with strong battery performance tailored to user habits.