Jason Snell:
Over the years I’ve said numerous times that when it comes to battery life on iOS devices, Apple appears to have a target battery life in mind and builds its hardware—a balance of power-saving software, hardware efficiency, and battery capacity—to hit that number.
It’s an observation born out of reading spec sheet after spec sheet over the years while writing reviews of new iPhones and iPads. Every year, people who are frustrated with their iPhones running out of juice before the end of the day hold out hope that the next iPhone will ameliorate the issue. In general, those people have not been satisfied.
Turns out, every iPad has gotten 9-10 hours of battery life. There’s a little more variation on the iPhone side of things, but not much until you get to the 6 Plus.