I’ve experienced exactly that myself after a previous 14.x update. Restarting phone did not help. What eventually got it to go away was installing the 14.x+1 update. Very unpleasant experience because you realize it’s entirely out of your control and there’s nothing in Apple’s release notes that would give any indication. And of course without any rollback opportunity it’s essentially a gamble anyway I’m afraid.
My iPhone X (3-ish years old, 14.7.1) dinged me recently to tell me that my battery was significantly degraded. Per the Battery Health setting, the battery is at 87% max capacity, and I should replace it. I haven’t because even though I use the phone all through the day, by day’s end, the phone nearly always has 40% or more charge left. I’d probably upgrade the phone before spending the money on a new battery.
I have an Apple Watch paired to this phone, but looking at the Battery Usage by App, seems like the “Find My” is the biggest memory drainer for the least amount of interaction. But not unreasonable so as to drain my battery by day’s end.
What about backing up to iCloud (or the Mac, with encryption on so you don’t lose some sensitive things), doing an Erase All Content and Settings, and then restoring from backup? It takes some time but is easy to do.
Good suggestion - I will try that this evening (it’s morning here)
Update: I need to check things like unpairing the Apple Watch, disabling Find My etc before backing up then erasing the iPhone:
( that Support page is for swapping to a new phone but it seems to apply to resetting an iPhone and restoring from the backup)
You’ll definitely need to turn off Find My, but I’m not sure you need need to unpair the Apple Watch, since it will be the same phone afterward.
Since both our phones are suffering this annoyance I decided to try a few experiments to isolate the cause before doing a reset.
Yesterday I turned on Low Power Mode on my phone - no obvious change.
Today I will turn off wifi on my phone.
Update: That was interesting - the discharge with wifi off was about half that with it on. I have no idea what processes might be using so much wifi.
My iPhone 8 Plus started doing this a few weeks ago too. Down to 20% by lunchtime, even though the use was the same the previous day. Normally it would be more than 20% at the end of a day.
My battery health is 88%, which I figure is not bad for a phone that’s coming up on 4 years old.
But something changed recently that I’m not aware of that has drastically affected battery life.
Similar experiences here over the past month or so with an iPhone 7: I’ll go to sleep with the battery at around 93% and wake up to find it around 70%. Yesterday I checked the phone around 3:00 with a reading of 54%, and around 8:00 I had a low power warning and only 2% charge.
The battery drain is definitely associated with wifi. This snapshot of the Battery settings shows (from midway across) discharge with wifi off then, after lunch, the wifi on. The graph is much steeper with wifi on.
The start of the graph is also with wifi on, then it moves to charging at night.
My guess is that 14.xx introduced some background activity whenever connected to wifi. Maybe artwork for music or similar unwanted downloads is active? I don’t use iCloud for photos or backups so it can’t be that. I do have an Apple TV and Homepods so handshaking with them is a possibility.
I feel like giving Feedback to Apple suggesting that they look at this discussion!
2 Likes
Based on what you’ve shown, I suspect some app on your phone is making lots of network use when WiFi is connected, but refrains when WiFi is turned off, perhaps because it requires permission to do the same over a cellular connection. But if that were the case, I’m sure the culprit would be appearing in the Energy Usage chart under Settings > Battery. I’d be very surprised if any system services were using that much network data!
I’ve seen occasional heavy drain on both iPad and iPhone. Looking at the Battery preference, it seems the App Store was running (even though I didn’t launch it) and chewing up the battery. I don’t have a lot of apps (compared to other people) on my phone. Pad but not Phone are set for auto updating.
It -feels- as if App Store is doing background processing and possibly updating of the system stuff, but I have no idea if that is the case. (iPhone 12 Pro, 2020 iPad)
I’ve seen this before and, for me, turning off Settings / App Store / Video Autoplay seemed to fix that battery issue. If I reset my phone and set up as scratch, that’s one of my steps when I set up the new phone.
1 Like
“autoplay” as a default is evil in all cases! (But on my phone at least this is off. We’ll see if I get a reccurance of the App Store drain.)
You can carefully tap a region on the graph to see which app is doing the most draining. Messenger apps tend to do strange things and apps that like to check-in too as well as location & background refresh apps.
About once a month, if I think of it or if my iPhone SE (1Gen) acts too weird, turn everything off. and do a hard restart. (Don’t make this too much of a habit; just a last resort.)
Settings / App Store / Video Autoplay Off seems to have fixed it. Both phones had it turned on by default - creepy! The drain with it turned off is about the same as when wifi is turned off.
How did people discover this obscure “trick”?
1 Like
All I can say is that when I saw the App Store was using so much battery I went into settings to see if there was some way to make it use less battery, and I noticed that setting. I hardly ever use the App Store - I go into it every day or two to update apps, and maybe once a month look for a new app for some reason (it’s probably less often now,) I never want video autoplay ever anyway - I want videos to start when I activate them - so I was glad to see that changing that one thing fixed the App Store battery issue for me and turned off videos as well.
Interesting…my two year old iPhone 11 (not Pro) has 85% Max capacity?
Rich
The battery drain problem is back! As predicted, my battery health has not dropped below the 80% apparently needed for Apple to fix it under warranty (expires any day now).
I recently installed an app that connects to a camping device (ironically a smart 50Ah battery) by bluetooth and that could be the culprit, although it doesn’t show up as a high devourer in the battery settings of the iPhone. Also installed a Dlink app for setting up a wifi network.
I have force-quit both of them to see how my phone goes tomorrow.
Now running iOS 15.1.1
Ok - I have replaced my iphone 8 with an iPhone SE (acknowledging that the SE is about to be updated!). The transfer was seamless - it even prompted to update to 15.3.1.
The battery drain issue is back! 
Video Autoplay was off in Settings. The bizarre thing is that the Home app is consuming 32% of the battery energy even though I rarely use it on the iPhone and, of course, the iPhone does not act as a Home Hub (maybe I should check if that has quietly changed?).
Another possibility is that I have selected iCloud Backup for the new phone (but disengaged it after first backup as I prefer local backups - Mojave/iTunes). I don’t see why a non-functioning iCloud backup would affect battery life.
A new phone, or a phone recently restored from backup, or a phone reset and rebuilt from scratch, can take a few days to do some background processes that can use more battery than usual. Give it a few days to settle down. It may be that you still have an issue, but battery usage may settle down a bit, too. Also, as I recall the battery report isn’t always useful during this period.
1 Like