Battery drains quickly, significant drop in battery maximum capacity

With your cycle count is shows your Battery Health is right where it is expected to be. On average you will see about a 1% drop for every 50 charge cycles. The iOS update does not change the cycle count of your battery and it is expected to last 1000 charges cycles before needing to be replaced when it drops below 80%. The battery drop is not linear meaning it will not drop on a regular schedule, and some months may not drop at all and other months may drop more.

Not surprising to see Instagram at the top of the list for the app consuming the most amount of battery. This single app is usually the one seen for all reports of battery draining problems on a device. It is not even specific to iPhone or iOS 26 as even Google has called out Meta for the amount of battery draining seen an Android phones with the use of the App.

We can hope Meta will respond with an update that will ease its use of the battery, it is a simple photos sharing app that does not require extensive battery use. There have been 11 updates to it in just the last month with the most recent one being 3 days ago. The problem is that Meta generates its revenue off the data that it harvests on its users to sell to advertisers, and that is why the app is free to download. You can look at the data Instagram collects by viewing the Privacy report in the App Store and ask why that is needed for a simple app:

• Contact Info
• Health & Fitness
• Financial Info
• Purchases
• Location
• Contacts
• Search History
• Browsing History
• User Content

Just try removing the app and compare your results. Not saying you cannot install it again, but just try for a day to see if it makes a difference. When installed it continues to run in the background even when not using the app and every notification will wake the app to process the payload. Accessing on the web has been seen to dramatically reduce the battery drain, because the browser does not have access to your data like the app does, and will not be running in the background.

• What are the Charge Cycles on your battery?
• Post a screenshot of Settings > Battery with the green battery graph for the last 24 hours and the apps consuming the battery.

For Instagram specifically, you were not using the same version of that App while you were on iOS 18. Considering that there have been 11 different versions of the app just over the last month, it would be very difficult to track those changes and the effects of each version. The exact same thing has been seen very recently over at the Samsung forum with the Instagram app draining their batteries as well, with this one being just 2 days ago.

https://us.community.samsung.com/t5/Galaxy-S24/Battery-Problem/m-p/3409275

I can only recommend to try what I suggested and compare your results. It makes no difference if you use Instagram or not, as the background processes will continue to drain your battery when it has not been opened, so it would need to be removed to test. It is difficult to ignore the obvious clues for troubleshooting battery drain when you see the exact same app on the top of the battery usage on those devices and also with the same thing being reported on devices from other manufacturers.

Read The last update killed my battery! - Apple Community

I believe you are missing the point here.

Senior contributor Mac Jim ID is correct, you have allot of background activity going on.

I’m not going to lecture you or anyone on how to use your device. That’s not the point in this case.

Learn why ⇢ the battery in your iPhone drains too quickly for details.

Good luck! 👋🏼😉