So, my iPhone 6 Plus battery has been draining very badly.
Whereas I used to get over a day on a single 100% charge, I barely make it half a day now. Even the charging in takes whole night even on a 10W iPad charger.
Everything I have observed lends me to believe that it is a battery issue. However the Apple Diagnosis concludes that the battery is alright and the problem probably is software related.
From the battery usage of the last day or of the last week, I don't see any app consuming too much battery - Gmail background activity even when it's background activity has been disabled is the only suspicion.
In the diagnostics and logs, obviously there's a ton of diagnostic information.
Reinstalling all of these and restoring the 64G of data is a painful process, I'd avoid unless I'm sure it would fix the issue that currently exists.
Anyway I can ascertain that the battery drain right now is absolutely software related?