Severe battery life + iOS9 downgrade

[Jensm]

Since iOS10, my iPhone 5S has had a comically bad battery life. I upgraded the day it was released — and the next morning I went on an 8hour drive along the west coast. I would have my phone running Google Maps, and charging in the car USB slot, and the battery would go DOWN 1% every five minutes or so.

I've used iOS10 for these past 4 months now and it's not getting better. I've replaced the battery, and done a complete reset of the phone while trying not to install heavy background tasking apps (or limiting the data to them / running battery save mode). Nothing works.

I can start a class with 100% battery, have my phone on without getting any notifications — 3 hours later it's in the 20-40% range. I've started turning my phone off during longer periods to save battery life.

Is there any easy way to revert back to iOS9 now that they've stopped signing those releases? Is the only way to jailbreak the phone or is there another option?

Appreciate the help,

 

[C DM]

There is no way to downgrade. It's sounding like there's something off with your device. Have you tried a complete restore as new without using a backup (and not even logging into iCloud or anything else), just to see how that behaves for a day or two?

 

[Jensm]

Thanks, yes I tried restoring it as a new device without much luck. I'm pretty sure I went a few days without iCloud even, but I might try to do it again. The device can feel hot to the touch sometimes without being used, so I'm guessing there's some kind of background process (bug) that is using way too much CPU when phone is idle.

 

[Mlrollin91]

What is your average cellular strength? 1-2 or 3-5 bars.

 

[phobos512]

What apps are using your battery up according to the list in Settings? Something sounds really off here.

 

[Freakonomics101]

My mom's iPhone 5 doesn't even die that quickly, and she's currently on 10.2.1