Battery life is one of the most important things to consider when buying a new smartphone. Most phones need to be charged every day, but if you constantly have to keep it topped up on the mains just to get through the better part of the day, then it quickly becomes an annoyance that belies its so-called 'smartness'. Ideally, you only want to charge your smartphone once a day, preferably at night before you go to sleep, but that's not always possible if you're a heavy internet user and like watching videos on the commute home.
A good indication of a phone's battery life comes from how large its battery is, which is rated in mAh. The higher the mAh rating, the bigger the battery, so phones with higher mAh ratings should (theoretically) last longer. This isn't always the case, though, as other factors such as screen brightness also play a big part in how quickly it drains the battery.
To see how your phone stacks up against the rest of the competition, we've put all our battery scores from 2014 in one place, letting you see which phones are the kings of endurance and which ones can barely make a sprint finish. In the graph below, red bars signify Android smartphones, while blue designates iOS. Windows phones are shown in green.
HOW WE TEST
To measure a smartphone's battery life, we run a continuous video playback test. We made the video file using a handful of chapters from Spiderman 2, encoded to H.264 and looped to epic lengths. We then playback the file and record the sound being outputted from a pair of headphones, allowing us to measure how long the file played for before the battery failed. In Android, we've always used MX Player for playback, but for Windows and iOS devices, we use the phone's internal video player. We also turn off any automatic brightness and sleep settings and set brightness to a uniform level.
THE RESULTS
As you can see from the graph below, there's a huge discrepancy in smartphone battery life, with more than fifteen hours separating the best battery life from the worst. On average, Apple's iPhones come out the best, with an average battery life of around 13 hours and 25 minutes. Android phones come in second, with an average battery life of 11 hours and 40 minutes, while Windows phone only last an average of 10 hours.
However, there are plenty of Android phones that last much longer than any of Apple's iOS devices, including the excellent Sony Xperia Z3 Compact, which can last for a massive 20 hours of continuous video playback compared to the iPhone 6's 12 hours and 58 minutes under the same conditions.
That makes the Sony Xperia Z3 Compact our Expert Reviews Smartphone Battery Test award-winner for 2014.
