iPhone 15 Pro Max gets one hour extra battery life thanks to iOS 18 optimizations

As part of his iPhone 16 coverage, Chinese blogger Geekerwan did a battery test of the new flagships, comparing all the iPhone 16 models to the iPhone 15 Pro, iPhone 15 Pro Max and some Chinese Android flagships.

Mirroring other testers’ findings, the iPhone 16 Pro Max set new records for battery longevity, easily clearing 10 hours of life in his test. But what’s perhaps more interesting is that the 15 Pro Max actually gained an hour of extra battery life running iOS 18, compared to when the test was conducted on the same phones running iOS 17. The 15 Pro also saw proportional improvements …

Obviously, all battery tests are somewhat synthetic benchmarks, and are not necessarily accurate of real-world usage. However, it is notable that this particular test is not just something trivial like playing streaming video on repeat.

The Geekerwan test involves using WeChat for texting, voice and video calls, browsing the web, using Douyin (TikTok) and playing the game Genshin Impact. These activities are looped, sequentially, until the battery dies.

Under those conditions, iOS 18 helped extend the runtime of the older phones.

The iPhone 15 Pro previously lasted 6 hours and 22 minutes. Under iOS 18, it lasted 6 hours and 55 minutes. Similarly, the iPhone 15 Pro Max went from 7 hours and 56 minutes to 9 hours and 2 minutes.

On the 15 Pro, that’s about half an hour of extra juice, based on these findings. On the 15 Pro Max, that’s an increase of more than an hour. These gains be achieved for free, just by updating your operating system.

As to an explanation for the dramatic improvement, Geekerwan points to changes in how the iOS 18 job scheduler exploits the performance and efficiency cores of the A17 Pro chip.

In brief, it seems that iOS 18 waits longer before boosting the core frequencies of the processor. This means for shorter, burstier, tasks, the system uses less power and results in less battery drain.

(During the September iPhone event, Apple repeatedly acknowledged the “advanced power management of iOS 18” helping with iPhone 16 battery life. This may be what they were referencing.)

Although some benchmark scores may be slightly worse because of this change in resource management, in regular use there should not be a noticeable difference in system performance.

If you want the best battery life though, you should consider upgrading to the iPhone 16 Pro Max. That phone tops the test chart with a battery life time of 10 hours and 23 minutes, almost an extra hour and a half compared to the iPhone Pro Max running iOS 18. The 16 Plus also clocks in at an industry-leading 10 hours. iPhone 16 Pro and iPhone 16 die at around 8.5 hours, still easily eclipsing their previous-generation competition.

Watch Geekerwan’s full video here: