Hello everyone,
I'm posting here to see if you can give your opinion about my situation. I'm using an iPhone 7, bought a few weeks after its launch, and since around October-November 2017 I'm seeing a quite undesirable battery behavior.
I charge the device to a 100%, and when waking up around 7-8 h later I see the battery has dropped to the 75-80% level.
Seeing this, I did several tests: making sure Background updates are off, localization services turned off(apps and system), no iCloud updates or backups, etc.
Went to a first appointment at an Apple Store, and after doing the battery analysis they saw this odd behavior of the battery being used. They told me to restore the iPhone to is factory settings (we did it there) and in the process it was updated to the latest iOS version (from 10.3.3 to the latest 11.x). After this, I restored my backup and used it the same way. Same results.
Went to an appointment again and the next conclusion was to restore again but keep using it as new, not restore anything. Did this, and this time I didn't download any single personal app, I just used the default apps. Didn't set anything, just the clean system as it comes for several days (I use the Mail with several work accounts and some other apps with media -Twitter, news sites, etc.- that could be causing this, so this time I didn't set them to not have them interfering). In the end, same results: the phone drops 25% of its capacity without doing nothing.
This is happening even with Low Power mode turned on, and even leaving the phone on Airplane Mode all night. The battery drops to the same ~75-80% level after 8h of standby and 0 minutes of usage. I get the battery at a 10% level after around 3h of usage time.
So... Is this normal? I have gone to the latest appointment now, and according to the guys at the Apple Store, they don't see anything wrong on the battery diagnostics, and the only thing they can offer me is to pay the now 29€ to replace it, without any warranty that this may solve the problem.
I'm pretty sure this can still fall under the 2-year consumer warranty (EU- Spain) but they are not being collaborative at all. Today they have dismissed all the test they told me to do and all the screenshots they told me to take (so that they could have more "proof" next time to do something about it).