iOS 27 Is Draining iPhone Batteries. Here’s What Apple Actually Says.

Last updated: September 20, 2026

iOS 27 battery drain is the complaint of the week. Apple released iOS 27 on September 14, and there’s a long MacRumors forum thread where people have been trading battery reports since the first beta.

I haven’t installed iOS 27 yet, so this is what Apple has put in writing and which parts are coming from blogs.

Is iOS 27 battery drain normal?

Yes, and that’s Apple’s word. Its support page on software updates says: “Immediately after completing an update, particularly a major release, you might notice a temporary impact on battery life and thermal performance.”

Apple calls that normal because the phone “needs time to complete the setup process in the background, including indexing data and files for search, downloading new assets, and updating apps.” The heat is covered too. Apple’s page on iPhone temperature lists finishing a software update, “particularly to a major release,” as one of the times a phone feels warmer.

How long does it last?

Apple doesn’t say. The word it uses is “temporary” and there’s no number of days attached.

The several days figure comes from Ben Lovejoy at 9to5Mac, who wrote that the background work “may last several days” and pinned the worst of it on the phone re-indexing itself for Siri AI. That’s his read, and Apple’s page doesn’t say either thing.

Apple’s page also says new features can mean “some users may notice a small impact on performance or battery life,” so a little of the drain may stay.

What can you do right now?

Open the Battery screen and let the phone tell you what’s eating the charge. These steps all come from Apple’s page for a battery that drains too quickly.

• Open Settings and tap Battery. Apple puts its own suggestions above the Daily Usage chart.
• Tap View All Battery Usage to see which apps are using the most.
• Turn on Low Power Mode. On an iPhone 15 or later it’s under Settings, Battery, Power Mode. On older phones the switch is right on the Battery screen.

When should you worry?

Worry when the phone itself flags a problem. A few warm days after an update isn’t that.

Go to Settings, Battery, Battery Health. If you see “Your battery’s health is significantly degraded,” Apple says a replacement battery restores full performance and capacity. That’s an aging battery, and iOS 27 didn’t do that. For heat, Apple says that if there’s no temperature warning on screen, you can keep using the phone.

If it never settles and Battery Health looks fine, I’d contact Apple Support, and that’s my suggestion since Apple gives no deadline.

Why this one doesn’t surprise me

I was on Android for years and I’ve only had an iPhone for about three years, and the whole time I was on Android I always heard about something affecting the battery on iPhones. So this doesn’t surprise me.

I’m not saying iOS 27 does this. But I suspect there’s a little bit of enshittification in how this usually goes, where a new iOS runs well on the new phones and drains the old ones, and that nudges you toward buying a new one. That’s just a guess, not gospel.

There is history behind the suspicion. In December 2017 Apple admitted it had been slowing down older iPhones to stop unexpected shutdowns, and apologized. NPR reports it later agreed to pay up to $500 million in a class action and $113 million to more than 30 states, without admitting wrongdoing.

Frequently asked questions

Check the Battery screen again in a few days. I’ll update this post if Apple says anything specific about iOS 27.

Related reading: How to get off the Siri AI waitlist | iPhone 18 Pro price increase | New to AI? Start here