iPhone 18 Pro battery drains quickly with low screen-on time

I had the same problem with my iPhone 18 Pro. I lost around 60–70% of my battery during 8 hours at work. I only sometimes checked a few apps — Weather, Messenger and WhatsApp.

On the first day, during the first configuration, my iPhone restarted 4 times in a row. I lost around 30% of my battery, and it was really hot. The next day, my battery was horrible. Even when my phone was locked, my battery was still draining.

Days 3 and 4 seemed to be better. My battery started working better, but it was only for two days. On days 5–7, my battery started getting worse than on the first and second days.

Of course, I always read a lot of information saying that this is normal. The battery needs more time, but I feel that it is not normal. I understand that the battery can work worse for a few days, but not 1% every 2–3 minutes. My iPhone 13 Pro, which has only 76% battery health, sometimes works better.

I tried everything, but the battery kept getting worse.

Today, I contacted Apple Support. My iPhone had a few diagnostics. I heard different feedback. I heard that it was normal, that my phone needed more time, and that a new version of iOS would improve it. But finally, I heard about a red bug — a software problem, and the software was unstable. This problem had an impact on my battery.

My iPhone is going to be returned. I’m waiting for a new iPhone.

I recommend running diagnostics on your iPhone as well, because this doesn’t look good.

Screen Time is a useless number when attempting to use it to correlate with Battery Usage. For your current device, I doubt any of the background processes have completed yet to index your files. You can see in your first graph that the light gray bars are representing background usage and that is expected when initially setting up or after an any Software Update for about 4 days. With iOS 27, there are additional Siri & Search Optimizations performed that may take a couple of days more. You can see at Settings if the Siri & Search Optimization has ended yet.

As far as any Software Update, Apple provides documentation on what you should expect for a short time after the update, and not only is that increased battery drain, but also heat and some UI lag.

About Apple software updates - Apple Support

After you give it a couple more days for the spotlight indexing and also verified that your Siri & Search Optimization has completed, then post those 2 graphs again along with the top 5 apps that are consuming your battery. That is much more relevant in determining Battery Usage than the Screen Time value.

Disabling Background App Refresh does very little as far as battery drain goes and does not stop Background Activities like many think. The only thing it stops is the UI update to reflect changes and does not stop the other background processes that are performed, especially those used for data harvesting by Social Media apps.

It seems you are being a bit obsessive about battery usage by disabling even useful features on your phone. Just charge your phone all night, every night using the Optimized Battery option and enjoy your phone. A Charge Cycle is not actually how many times you have charged your phone, it is how many times it has drained from full capacity to empty over a period of time. Leaving your phone unplugged overnight is just wasting Charge Cycles as you are relying on your Battery to perform the normal and scheduled background processes intended to be run when you are not using your phone.

Looks ok to me. You chose to recharge at 6pm at 40% Why not leave it til bed time?

And you only charge to 80%. Absolutely pointless in a busy phone,

If you had charged to 100% overnight using optimised charging you would have a full day's battery and a healthy charge at bedtime

Same issue. Battery drains way too fast. I tried connecting to my mac to check for the Indexing Progress, it says:

debug	09:23:46.295885+0200	Preferences	PipelineCompleteness: hidden
debug	09:23:46.324350+0200	spotlightknowledged.updater	fetchPipelineCompleteness: display=hidden days=1 percent=1.000000 calculatedAt=2026-09-23 05:14:31 +0000

A full days use starting at 85% seems reasonable.

I suggest using optimised charging to 100% instead of charge limit and charge every night while you sleep

As a longtime Android user coming from a Pixel 9 Pro XL to my first iPhone (18 Pro Max), I’m surprised by how fast the battery drains. With minimal use, dropping to 65% by 6:00 PM feels excessive. While I hope performance levels out after a few days of indexing, the experience so far has been underwhelming—especially with iOS feeling a bit behind on several practical software features I took for granted on Pixel.

Draining very quickly with normal usage. Charging my 18 pro 2 times in 24 hours

I have checked with apple support and they said that my phone was fine. How exactly did u end up finding out about the bug?