after update to ios 26 battery drains too fast

What model iPhone, how old is it, and what do you see when you go to Settings/Battery/Battery Health?

If you are charging it just before you use it there is no benefit to charging only to 80%; you should charge to 100% as it will give you 20% more life.

But, as I said, the absolute best way to get maximum use on a charge, as well as slow the decline of battery capacity long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night leaving it powered on. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern. If you enable iCloud Backup (Settings/[your name]/iCloud - iCloud Backup) the phone will back up overnight also, assuring that you can never lose more than the current day’s updates. Here's more information→About Optimized Battery Charging on your iPhone - Apple Support

lorelei113 wrote:

This update is awful. First off, visually it’s terrible. Beyond that. My battery is dead by mid-day with minimal usage. I used to be able to work my entire shift at work, which by the way is 12 hours, and it wouldn’t need charged. Literally every day, I have to put my phone on the charger by 1pm. That’s six hours of the phone, but I’m not even using it. It’s in my pocket.

Go to Settings>Battery. What is using all the battery?

There has to be a fix, or the update needs to go away.

In all likelihood, it's not iOS. It is more likely that you have a third-party app that is not properly updated.

I can’t do the factory reset, because I don’t have a computer back up. So please help.

Back up to iCloud.

Without knowing what “too fast” is it’s difficult to provide guidance. If you charge the phone overnight, every night, with Optimized Charging enabled and you don’t need to charge until the next night then the iPhone is working as designed.

All energy is used to power apps, so if it is using more then you expect the reason is either you are using apps that demand a lot of energy, or your cellular signal is very weak.

In addition, from→About Apple software updates - Apple Support:

Immediately after completing an update, particularly a major release, you might notice a temporary impact on battery life and thermal performance. This is normal, as your device needs time to complete the setup process in the background, including indexing data and files for search, downloading new assets, and updating apps.

This update is awful. First off, visually it’s terrible. Beyond that. My battery is dead by mid-day with minimal usage. I used to be able to work my entire shift at work, which by the way is 12 hours, and it wouldn’t need charged. Literally every day, I have to put my phone on the charger by 1pm. That’s six hours of the phone, but I’m not even using it. It’s in my pocket. There has to be a fix, or the update needs to go away. I can’t do the factory reset, because I don’t have a computer back up. So please help.