iPhone 16 battery draining fast after iOS 26.3.1 update

Wait 4-5 days for the iPhone to automatically index everything on the phone. The battery is working extra hard during this time.

Things will very likely improve in a week or so.

4%-5% overnight is much better than average. If you don’t charge overnight you will typically see 20%-30%.

There is never a time when your iPhone is doing nothing, even if you are not using it. It updates apps like weather, it maintains a “handshake” with the cellular network, it receives email and text messages, it receives notifications that you have enabled.

The phone is designed to be charged overnight with Optimized Charging enabled and with automatic backups on. If you don’t do this you are not maximizing the capabilities and longevity of the battery.

If you want details, see:When to charge your iPhone or iPad | Communities

After the week to finish indexing, post the screenshot of Settings > Battery > View All Battery Usage, and include the green battery graph and the top 5 apps consuming your battery.

Hello~ In addition to the already helpful insights…

If the battery in your iPhone or iPad drains too quickly - Apple Support

~Katana-San~

Martin25o wrote:

I bought a new iphone 16 and its battery is dying very fast. its has 100% battery life and 6 cycle counts ,its started after I updated it into IOS 26.3.1. What should I do?

Can you define “very fast” please. If you charge your iPhone overnight every night and it doesn’t need to be charged during the day it is working as designed.