A slight drop in battery life after installing a new iOS update is expected, as your iPhone runs background tasks that temporarily use more power. With iOS 18, you can check Settings > Battery for “Device Setup & Updates” to see if these processes are active.
Battery performance should return to normal once these tasks are complete, but in the meantime, you can try a few tips:
Lower screen brightness
- Disable Wi-Fi Assist (Settings > Cellular)
- Reset Network Settings (Settings > General > Transfer or Reset iPhone)
- Enable Dark Mode, especially on OLED screens
If the battery drain continues, consider disabling Apple Intelligence if you don’t use its features. Also, check Settings > Battery to see which apps are using the most power. Apps with high background activity could be the cause—disable Background App Refresh for them under Settings > General. These steps may help improve battery life.