Q: iPhone 5S getting incredibly hot and high battery usage after iOS 8 update

I Had this problem with battery dying SUPER fast even in standby with nothing running on iphone5.  company phone and had it replaced to 5s. SAME PROBLEM with fresh phone created as new setup (no restore)

Long storyshort if if I am signed into iCloud the battery is toast FAST.

if I log out of iCloud thebattery is back to NORMAL.

i am baffled

Seems like an icloud+ios8 peoblem is what I'm saying.  If you are having his issue go to SETTINGS>icloud and sign out

let me know if this Works for anyone else

HI,

I had the same problem. All you have to do is go to Settings>General>Reset> Reset all setings.

it helped me.

Monkeyclaws - I tried turning off iCloud on my iPhone 5S, but that didn't help.  I also tried disabling my Exchange mailbox, but that did not help either.  Today, I installed the new version of iOS (8.1) over-the-air, and so far it seems a lot better than before.  It isn't getting hot or draining super fast, but I don't want to declare victory just yet, since it has only be a couple hours since I installed it.

Well 8.1 did NOT fix mine. 

Over the air updated, after install I reset all setting/content to start fresh.  Once done I only signed into icloud and NOTHING else (no apps installed extra).

I then charged to 100%, after that i unplugged and intentionally did not touch the phone for an hour and a half.....i was down to 81%.

I then signed out of icloud, it's been 45 minutes since that and  my battery is at 81%

This is an odd problem, especially since i have the same thing happen on my old iphone 5 and this brand new 5s

Second level Apple support told me to call in today if 8.1 didn't fix this so i'll try them tonight.

This never happened me ever: being scared of upgrading iOS. Since I went to a iPhone 4S from the original iPhone, or upgrade Mac OSX on my Mac since first version. All was great when I got my 5S, with iOS 7. But with iOS 8, the CPU chip is working too much when it should be just idle or low usage. Is iCloud services responsible for all our problems now with fast battery drainage?

Now I am doubting to go up to 8.1 from 8.0.2. The description of the upgrade doesn't mention anything about addressing the high CPU usage and high battery drainage that started with iOS 8.0 and has gone the same up to the recent 8.0.2 upgrade.

So I'll wait this time to hear if the problem was fixed with this latest upgrade, or not. I hope Apple has heard this community.

Same issue with 8.1 and 5S. 1% per minute.

Monkeyclaws - Sorry to hear upgrading to 8.1 didn't solve the problem for you. It was super frustrating when my phone was draining like crazy and heating up, so I understand how you feel.  I have been running 8.1 for more than a day now, and I think my phone is holding a charge longer and not heating up as much as it was with 8.0.2.  I didn't even have to reset anything after the OTA update.  If I notice mine draining fast again, I'll post an update here.

Ultimately it was necessary to restore through iTunes and set up as a new phone.  It is inconvenient but it is the only thing that worked with one of two iPhones that had the rapid battery drain issue.  We have 2 iPhones and 2 iPads.  Each were updated with iOS 8.0, 8.0.2, and 8.1 in succession.  Each without issues until the battery drain problems with the two iPhones.  One responded with a hard reset.  The other required the aforementioned restore and set up as a new phone.  I took a step-by-step approach and attempted to trouble shoot as a non-technical expert starting with soft and hard resets. This high battery drain was clearly related to problems with the iOS 8.1 install and in one case needed a complete reinstall including selecting the set up as a new phone option to solve it. 

My recommendation is to try the following steps in order of least troublesome to most troublesome: soft reset, hard reset, and backup and restore as a new iPhone.

1. Soft reset - Go to Settings ->General -> Reset -> Reset All Settings enter pass code. This resets setting without removing any data or photos from your iPhone.

2. Hard Reset - Hold down the sleep/wake top button and the home button at the bottom of the screen at the same time until the screen shuts off.

3. Restore -

     Plug iPhone into your computer with iTunes and to a backup to computer  (or iCloud).

     Turn off Find My iPhone – Settings -> iCloud -> Find my iPhone -> Off

     Go to iTunes and select your device then Click Restore

     Follow the prompts and the iPhone or iPad

     Monitor the install, it may take a while. When it is complete you can try doing a restore from backup.  I tried this and it did not work.  I suggest skipping to set

     up as a new iPhone. You can then sync your data and restore.  It is a hassle to do it this way but with one phone this is the only thing that worked.

You can do a search for any of these type of solutions such as Wikihow: http://www.wikihow.com/Hard-Reset-an-iPhone

There are other searches that can be done to fine tune battery life.

I'm experiencing exactly the same issues. My phone was so hot to even touch, causing it to shut down. Apple should release an update to fix this problem. I never had any problems with IOS 7.1.2, but IOS 8 is full of problems. My phone hasn't been the same iphone since IOS 8. I've restored and everything, but it doesn't fix it. I would love a fix!!

I am also having my CPU max out indefinitely. I discovered that anything that deals with healthkit is the issue on my phone. Even after doing a full restore on my phone. Just opening my jawbone UP app with healthkit enabled created the problem, others as well. Once I disabled healthkit across all of my apps, the problem went away. I really hope they fix this soon, I enjoyed the few times healthkit worked....