iphone 16 pro battery drains faster after ios 18.5 update

If you fast charge your device it may get very warm, and may pause charging at 80% and display a message saying that charging has paused, and will resume when the phone cools down. This is normal when fast charging. It also won’t prevent you from using any app you have on your phone.

If you have just updated allow a couple of days for iOS to complete its “housekeeping"

Some apps that use a lot of energy or that use cellular data rather than Wi-Fi can cause the phone to run warmer. Worst offenders are Meta products (Facebook, WhatsApp, Instagram, etc), interactive games, watching streaming videos, and the Camera app. Recently the Amazon app has been causing excessive battery drain and heating. This has been reported by both users and Apple to Amazon, but there is no resolution yet.

And having VPN installed, whether using it or not, can also consume a lot of energy. But none of these can cause “overheating;” iOS will limit energy use to keep the phone safe.

First, an iPhone battery is not expected to last 24 hours. You should charge the phone overnight, every night, with Optimized Battery Charging enabled. If it doesn’t need charging until the next night it is operating with normal expectations. You should also enable automatic backup, so your phone is backed up every night.

There are many possible factors that affect battery life, discussed here→The last update killed my battery! - Apple Community