Opower's Barry Fischer said: we did this study, and we drained the iPhone 6 and 6 Plus to 0pc and the we measured how much electricity through a power monitor device it took to get to 100pc. The iPhone 6 takes one hour 50 minutes using a 12 watt usb power adapter and the iPhone 6 Plus took 2 hours and 30 minutes. The iPhone 5, by comparison, took a similar amount of time to the iPhone 6.