Monday, September 15, 2025 marks the day Apple is pushing out iOS 26 as the new major version update to the software of the iPhone. The successor to iOS 18 is so named to correspond to the year in which it will be most widely used – in this case, 2026.
iOS 26 brings a new look to iPhones with Liquid Glass, a design language based on the look of that used on Apple’s Vision Pro headset, and is now present across Apple devices including the iPad and the Apple Watch.
You can read about everything new in iOS 26 in my round up of the five best features, but one less exciting thing to be aware of is that shortly after updating, you might notice your iPhone’s battery running down a little quicker than usual.
This won’t definitely happen to your iPhone, but it’s something to bear in mind in case you notice a drop off in juice. Updating an iPhone from one version of iOS to a completely new one isn’t just a case of a lick of paint here and there. The phone has to completely reindex all your apps and data and reoptimise them for the new version of iOS.
This is much more complicated than changing a wallpaper or updating one app. Your phone is essentially reinstalling a completely new operating system.
This results in hundreds of necessary background processes that can take hours or days to complete. They don’t last forever, but they can often result in you noticing your iPhone’s battery life being a little worse than it was before.
This can also be a side effect of you using your phone more as you check out all the new features it has after the update. But the prime suspect is background processes.
Apple itself has an explanation for why battery life might be less than you’re used to once you’ve installed a new version of iOS.
“If you notice that your battery life has decreased after updating your iPhone, wait a few days and then check again,” the firm says on a support page on its website.
“Even though you can use your iPhone immediately after an update, certain tasks related to the update continue in the background and might affect battery life and thermal performance. While they are ongoing, you might see the Insight Ongoing iOS Update in Settings > Battery.”
It’s that “Ongoing iOS Update” notice you might see flagged in the battery section of your Settings app that indicates things are still working themselves out. After a short time, you should see things go back to normal.
In the past, people have blamed worse battery life after a software update on planned obsolescence, the theory that tech firms purposefully make your battery worse as time goes on to force you into buying a new phone.
It’s hard to prove this one way or another, but background processes in the first instance are the most likely cause. Secondly, new software features that come with free iOS (or Android) updates can result in more power being used, particularly on older phone hardware that might have less powerful processing power than newer models.
Thirdly, you might just be noticing shorter battery life thanks to the natural degradation of your phone’s battery capacity. The constant recharging and discharging of any battery in any product results in shorter longevity over time.
Instead of buying a new iPhone, you can invest in a new battery through Apple’s official service. It’s a little pricey at about £100, but that is cheaper than buying a new phone.