Friday, October 26, 2018 [Tweets] [Favorites]

Mysterious Reduced iPhone Battery Life

I’m not sure what’s changed other than iOS 12, but my iPhone’s battery is draining like never before. It can now drop from 100% to 50% sitting on my nightstand overnight. I thought maybe an app was doing something in the background, but the Battery area of Settings shows no activity whatsoever during that time.

And, for many years, I’ve been taking my iPhone on day hikes and recording a GPS track with MotionX-GPS. I carry an external Jackery battery just in case, but the internal one usually lasts the whole day, six hours or so of camera and background GPS use. No longer. On my last two hikes, the battery drained to zero in under an hour. The Battery screen simply shows that MotionX-GPS was running; nothing looks out of the ordinary.

The Battery Health display shows that Maximum Capacity is still 100% on this 18-month-old iPhone SE, although it notes that performance management has been applied due to an unexpected shutdown.

Previously: Battery Health and Peak Performance Capacity.

Update (2018-10-29): Rob Mathers:

My SE started draining more heavily earlier this year. Not to the extent of yours, but still bad. I got the battery replaced, with small improvements, but eventually caved and went to the XS, which is way better.

I do still wonder what changed…

Jeff Baxendale:

My 6s battery is at 88% max capacity (replaced last year for free) and says the performance throttling has been applied.

I’ve (+ my fam) generally noticed it draining faster too… trying to see what is doing it, but also hard to argue with how much more responsive the OS feels.

I’ve found that disabling Screen Time helped a lot. My iPhone is now at 75-80% in the morning (still lower than with iOS 11). I’ve also noticed that turning Screen Time on makes the battery start draining quickly. I also tried turning off Compass Calibration, but that didn’t seem to make a difference.

12 Comments

Something similar happened to my iPhone 6S after upgrading to iOS 12 in the days before I replaced it. The battery was replaced through the recall program, less than 2 years old. All I can say is that my iPhone XS isn't behaving similarly. Family members' iPhone 6 (now replaced with an XR) and 6S did *not* do similar things however.

Any time you get a major iOS update, battery life becomes terrible for a few days. I think there is a flurry of background processing (re-indexing the file system?) following major updates, and that consumes a lot of power until it completes.

I would question any battery health indicator that claims 100% capacity after 18 months. It probably does need to be replaced.

FWIW, my iPhone 6+ had lots of battery issues until I changed its battery a few months ago. It's working great now, even with iOS 12.

I’ve read several reports that indicate Screen Time may be responsible for this behavior. Some have said they return to old battery usage patterns after disabling it.

@David That’s why I waited until a month after iOS 12 came out to see whether it would get better.

@Paul I’ll try turning Screen Time off. Thanks!

I recommend filing a bug. That shouldn’t happen, and if they come back and ask for the right logs they should be able to figure out what’s going on.

My wife‘s SE (2 ½ years old, original battery) drains a little faster under iOS 12 than before, but not much, as far as we can tell. Screen Time is off, since the moment the OS was installed. At the same time, the device feels quite a bit faster / more responsive than under iOS 11, that may account for the faster draining of the battery.

My iPhone 6, which had its battery replaced last year. Is also draining it faster after upgrading to iOS 12. It too has become more responsive, but long-running tasks like listening to podcasts with Overcast (with its added audio processing for higher speeds) cause an appreciable dip in available power.

I don’t have permanently active background processing of any other kind. Not even e-mail fetching (only hourly checks of a personal account), and messaging apps account for around 15% of my battery use. But it seems to be 15% of a much smaller pie in iOS 12.

Michael Münch

I noticed the same on my iPhone 6s after upgrading to iOS 12. It has improved noticeably after disabling almost all Location Services for System Services - I currently only have Emergency Calls & SOS, Find My iPhone and Setting Time Zone enabled (Settings -> Privacy -> Location Services -> System Services).

My prime suspect is Compass Calibration, but I am still experimenting.

I had the same Problem in the Developer Versions... Reinstalling the Consumer versions solved the Problem.

I’ve had similar problems with my iPhone 8. Battery life hasn’t been good since I was on iOS 11 earlier this summer. I often hit 20% after about 3 hours of usage. I’ll have to try @Paul's suggestion and see if turning of Screen Time makes a difference.

Not sure if this is related, but my "Steps" count in Health app is reporting weird number of steps from time to time for some reason. E.g. fixed value per hour of ~ 400 steps during the night and such, when the phone should be at rest. This pattern started somewhere around September, so coincides with iOS 12 release..

I noticed the same thing recently on a trip: my friend and I each had an iPhone X, each running iOS 12.0. My battery was draining about twice as fast as his (and with less use!). I restored from an iCloud backup, and it seems much better now. I also turned off and back on Screen Time, so that could be part of it as well.

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