As part of his iPhone 16 review, renowned Chinese blogger Geekerwan conducted a battery test on the new flagship models, comparing all iPhone 16 variants with the iPhone 15 Pro, iPhone 15 Pro Max, and some Chinese Android flagship phones. In line with other testers' findings, the iPhone 16 Pro Max set a new record for battery life, easily surpassing the 10-hour mark. But what’s even more noteworthy is that the iPhone 15 Pro Max, when running iOS 18, gained an extra hour of battery life compared to when it was tested on iOS 17. The iPhone 15 Pro also saw a similar improvement in battery life.
While all battery tests are to some extent synthetic benchmarks and may not fully reflect real-world usage, this particular test is more comprehensive than simply looping a video. Geekerwan’s test involved using WeChat for texting, making voice and video calls, browsing the web, using Douyin (TikTok), and playing the game Genshin Impact. These activities were repeated in sequence until the battery was drained.
Under these conditions, iOS 18 significantly extended the battery life of the older phones. The iPhone 15 Pro, which previously lasted 6 hours and 22 minutes, now lasted 6 hours and 55 minutes after upgrading to iOS 18. Similarly, the iPhone 15 Pro Max increased its runtime from 7 hours and 56 minutes to 9 hours and 2 minutes.
For the iPhone 15 Pro, this means an extra half hour of battery life, while the iPhone 15 Pro Max gained over an hour. These gains are easily achieved simply by updating the operating system.
As for the reason behind this dramatic improvement, Geekerwan pointed out changes in how the iOS 18 job scheduler optimizes the use of the performance and efficiency cores of the A17 Pro chip. In short, iOS 18 delays boosting the processor's frequency, meaning that for shorter, burst-like tasks, the system consumes less power, leading to less battery drain.
Although certain benchmark scores might be slightly lower due to this resource management change, in regular usage, users are unlikely to notice any performance degradation. However, if you're aiming for the best possible battery life, you should consider upgrading to the iPhone 16 Pro Max. This phone tops the test with a battery life of 10 hours and 23 minutes, nearly an hour and a half longer than the iPhone 15 Pro Max running iOS 18. The iPhone 16 Plus also performed impressively with a 10-hour runtime. The iPhone 16 Pro and iPhone 16 lasted about 8.5 hours, easily surpassing the previous-generation models.