iPhone Battery Draining Fast After the iOS 27 Update? Here's the Fix
Why your iPhone battery drops faster after updating to iOS 27, how long it should last, and what to do if it doesn't get better after a few days.
If your iPhone's battery started dropping noticeably faster after you installed iOS 27, you're not alone. Battery complaints have followed iOS 27 since its September release, including on the iPhone Air and iPhone 15 Pro Max.
The good news: for most people, it's temporary.
Why it happens
After a big update, your iPhone does a lot of work in the background:
- Rebuilding its search index (so Spotlight can find your files, messages and photos)
- Re-analyzing your photo library
- Preparing data for Siri AI and Apple Intelligence features, if your iPhone supports them (see which iPhones get Siri AI)
- Updating apps in the background
All of that uses battery and can make your iPhone feel warm. It's usually most noticeable in the first 24 to 48 hours, and some people see it last up to about three days.
What to do in the first few days
- Leave it plugged in overnight on Wi-Fi. This lets the background work finish faster.
- Update your apps in the App Store. Apps not yet optimized for iOS 27 can drain battery.
- Restart your iPhone once the update has settled.
- Use Low Power Mode during the day if you need to. It pauses a lot of background activity.
If it's still bad after three days
Find the culprit
Go to Settings → Battery. Look at the apps list for the last 24 hours and 10 days. An app using lots of battery in the background is the usual suspect. Update it, check its settings, or delete and reinstall it.
Turn off Background App Refresh for apps that don't need it
Settings → General → Background App Refresh. Apple suggests this for fast drain. Leave it on for messaging and anything you rely on for notifications.
Check Adaptive Power
Settings → Battery → Power Mode. On supported iPhones, Adaptive Power makes small adjustments to save battery. It needs about a week of learning your habits to work well.
Cut location and display drain
- Settings → Privacy & Security → Location Services: set most apps to "While Using".
- Turn off the Always-On display if your iPhone has it.
More settings in how to make your iPhone battery last longer.
Check battery health
Settings → Battery → Battery Health. If maximum capacity is low (around 80% or below), your battery is simply worn out, and the update made it more noticeable. A replacement can fix that. See how much an iPhone battery replacement costs.
What not to do
- Don't keep closing apps from the app switcher. It doesn't save battery and can use more.
- Don't downgrade to an older iOS. It's usually not possible once Apple stops signing it, and you'd lose security fixes.
- Don't reset all settings as a first step. Try the fixes above first.
Will Apple fix it?
Apple often improves battery performance in point updates like iOS 27.1 and 27.2. Keep your iPhone updated: Settings → General → Software Update.
