iOS 15 has been out for less than 24 hours, and people are already screaming about poor battery life.
I'm not surprised.
Because this always happens.
It's more predictable than Apple launching a new iPhone every fall.
Here's the deal. We can break the battery drain complaints into two categories:
"What the heck, Apple! My battery dropped many percent while installing iOS 15!"
"Whoa Apple, my battery life has been terrible since installing iOS 15!"
First, heavy battery drain while installing iOS 15.
It's a heavy process. The iPhone has to download several gigabytes, unpack it, and then update the iPhone. That takes time, CPU power, and battery power. It's perfectly normal to see the battery plummet by many percentage points.
This is why I recommend having the iPhone on charge while the update is happening.
OK, but what about abnormally high battery drain afterwards? Isn't that abnormal?
Installing a new OS on an iPhone triggers a lot of stuff to go on in the background, from indexing to recalibrating the battery, and this can go on for hours or even days. Not only does this consume power, but the battery recalibration can give the impression that the battery is draining more rapidly when in fact it isn't.
Add to this the dual factors of a lot of app updates happening following a new release, combined with a lot of new features available that may put more drain on an older handset.
Use the iPhone for a few days normally and chances are all the problems will solve themselves.
If you go to Settings > Battery > Battery Health and battery capacity is over 80 percent then it's either just the normal stuff going on in iOS 15, or a bug.
Which brings me to bugs.
Remember how I urge caution when new iOS releases come out? Yeah, well this is why.
Not only could there be bugs in iOS 15 that affect battery life, but there could also be bugs in your favorite apps that need attention from the developer.
So yes, I know it's annoying, but just charge your iPhone more, and keep a power bank or charger nearby and things should settle down after a few days.