Actually his explanation is credible, cause rechargeable batteries do deteriorate over time.
Have you noticed that you have less charge left at nights before you recharge? I would find it extremely difficult to believe that your battery has the same charge after 4 years![]()
My batter has declined in quality over the past 3 years (I have an iOS battery diagnostics program that shows the battery only lasts 60% as long as it originally did) - but I have found that iOS has definitely become more of a battery hog.
The two most battery hungry pieces of hardware on the iPhone are the screen and the GPS. Over the years, Apple has been slowly adding more and more GPS usage in the background to iOS, which causes a pretty dramatic reduction in how long the battery lasts. Additionally, with iOS 7, they shifted to a very white intensive interface, which it seems to me also contributes to the battery lasting less time.
I've combatted the GPS by going through and turning off access to the GPS to several programs and services which just didn't seem to benefit me at all. IE, Facebook or CNN. Neither of those apps need my location - what the heck are they doing with it? Location based iAds, Popular Near Me, and Frequent Locations? Turned all of that off (I understand the benefit of Frequent Locations, but it seemed to be having my GPS turn on nearly all day, causing my iPhone to die before noon).
Just turning off all those GPS services caused my battery (which gets unplugged at 5 AM) to go from lasting until ~11 AM to now lasting until 5 PM.
I wish Apple would put GPS information right in the Control Center. It should have a button to instantly turn your GPS off, plus if it's in use it should tell you who is using it. Frequently by the time I make it to GPS page in Settings whatever was using it has already stopped, so I can't tell its gray arrow from any other gray arrow.