The frustration of a dead battery will be familiar to every iPhone owner. But what can you do to avoid it, other than use your phone less? Apple is good at squeezing maximum performance out of the hardware in the iPhone and that's one of the reasons that the iPhone's battery is comparatively small. The first iPhone had a 1400mAh battery, and seven years later the iPhone 6 has a 1810mAh battery, although the iPhone 6 Plus has a whopping 2910mAh offering.