There are lots of stories out there about this from the past few days, I'm just pasting in what I was just reading - https://www.forbes.com/sites/gordonkelly/2017/12/21/apple-iphone-battery-lif... Basically, iOS has a "feature" that deliberately slows down the phone based on the age of the battery. Apple's incentive here is obvious - get you to upgrade to the latest & "greatest", because damn the current model is really starting to feel it's age... Of course they never publicized that they were doing this or that a far cheaper battery replacement would restore performance, a trade off that no doubt many users would've made rather than shell out for a whole new model they don't really need. Some of the most crass and blatant profit driven software engineering I can think of.... Cheers John