I'm having the same problem with my 5S, except I *know* it has nothing to do with reception or signal; very strong.
A couple of weeks ago, just out of the blue, one day my iPhone 5S decided to go through the battery like nobody's business. We're talking with no apps in the background, going from a 100% charge before bed to 18% when I wake up six hours later.
The obvious stuff:
- Factory reset, setting up as a new phone (without restoring the backup)...no difference.
- Background refresh is 100% off.
- Apps that use location services are set to either "Never" or "While app is in use"
- No Bluetooth.
- Brightness set to the lowest possible
- Removed iPhone from its case to reduce the chances that it's an overheating issue
- No new apps were installed that might have started causing the issue, and in fact many apps had been deleted because I was running out of space.
I'm on iOS 9.3.2.
I took the phone to the Apple Store. They ran some hardware diagnostics and found no hardware problems, including with the battery.
One thing they did find at the Apple Store, though, was that "stacks+passd" shows up on the crash report like a rash...I tried Googling (and Binging and DuckDuckGoing) "stacks+passd" but got no results.
Any thoughts?? Of course, I could have them change the battery for $85 or send it off to iRescue and save a few bucks, but due to my job and literally needing an app on my iPhone to be able to do my job (security is a huge concern where I work and I need my phone for two-factor authentication) makes that *not* an option.
