Why does my iPhone 15 Pro battery drain faster after IOS updates?

Your iPhone 15 Pro may drain faster after an iOS update because the phone often does extra background work for hours or a few days after updating. That can include re-indexing files and photos, updating apps, syncing iCloud data, recalibrating battery estimates, and running new system features. It is usually temporary.

What to do first:

1. Give it 24–72 hours after the update, especially if it was a major iOS update.
2. Go to Settings > Battery and check which apps are using the most power.
3. Update your apps in the App Store, because outdated apps can misbehave after a system update.
4. Restart the iPhone.
5. Check Settings > Battery > Battery Health & Charging. If Maximum Capacity is low or there is a service message, the update may have made an existing battery issue more noticeable.
6. Turn off or limit battery-heavy settings you do not need: Background App Refresh, Always-On Display, high screen brightness, frequent location access, and push email.
7. If drain remains severe after several days, install the next iOS patch if available, reset settings, or contact Apple Support.

A quick test: if Settings > Battery shows one app with unusually high background activity, that app is likely the problem. If many system items are high right after the update, it is more likely normal post-update processing.