iPhone13 Pro crazy battery drain?

So my iPhone 13 Pro is about a week old, and the battery has been great, as I expected. But today it was terrible! Could it have been the iOS 15.0.1 update?

Looking at Battery in Settings, it shows that it was 100% at 6am when I removed it from the charger, and declined steadily until it hit 20% at about 6pm when it went to low power mode.

I watched no videos, played no games, and did next to no GPS (a few minutes with Transit, the public transportation app). Almost all my time was email and my Twitter client (Twitterrific). The majority of time the phone was in my pocket.

Apple claims this model could play video for 22 hours on a charge??? What could I be doing wrong?

Here’s a picture of the Battery app, if this link works:

High power consumption for a day or two following a system software update is not unusual. The cause is not clear (and Apple has never issued a statement about this), but I have always assumed it is due to rebuilding various caches and indexes.

If the problem persists for more than a few days, then you may have a different problem. In which case, I would suggest:

  • Power-off, wait a few minutes, then reboot
  • If that fails, make a full backup (via USB to a computer, using encryption so it will back up your passwords and account data), then do a full restore, which will wipe the phone and restore from the backup.
  • If that doesn’t work, then I’d contact Apple and have them check to see if it’s a hardware problem of some kind.
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Well day 2, from 6:30am at 100% to 7:00pm at 22%. A smidge better, but still awful for a two week old iPhone.

I did power-off & restart yesterday so that didn’t help.

I really think there is something wrong with 15.0.1 - I can’t conceive that the phone needs 20+ hours to rebuild caches,etc.

By the way there’s a big (but inconclusive) thread about this issue on MacRumors and if you go to discussions.Apple.com and search the iPhone section for “15.0.1 battery” a bunch of stuff pops up.

Guess I’ll wait for 15.0.2 or 15.1 or whatever.

Well day three was significantly better. After 15 hours from full charge I still have 50% left. Is it possible this is some bizarre but temporary side-effect from upgrading? Actually, even if it fully improves to how it was before the upgrade, two or three days of extremely poor battery performance is something customers should be warned about, if it’s truly predictable.

It’s not uncommon, as @Shamino noted, for battery life to suffer right after an upgrade as caches and indexes are rebuilt. I suspect Apple doesn’t warn about it because it’s impossible to predict how it will hit each individual device, depending on usage, and because the brand new battery generally does better than whatever it’s replacing.

macOS does say that performance may be hampered during initial optimization, which is partly why we assume the same is happening on iPhones.

You must be right. After three days or so the iPhone 13 went back to it’s usually good battery life, and the iOS 15.0.2 update didn’t affect it at all. So I guess it’s only certain updates affecting certain people. I surely got freaked out though - a $1k phone, going from great battery life to miserable battery life really had me worried that there was a hardware problem.