Yeah, my 6s Plus has the worst battery of any Apple product I owned. Constant shutdowns at the slightest hint of cold, battery meter in free fall to 1% and then it runs for 6 hours in that state. Capacity estimate says 80%, but I call BS, it’s more like 8%.
Fortunately my Xs is on the other end of the spectrum. It was at 100% for over a year. After 21 months and 267 cycles it’s at 95% capacity.
There’s a bit more going on with the 6s than can be explained by ”hey, it’s old”. I’ve had a total of 10 iPhones and iPads since 2008, and the 6s (Plus) sticks out like a sore thumb in the battery department. Much worse than anything that came before it. My 2010 iPhone 4 was just retired after sitting for 7 years in a 30-pin dock with the screen always on, showing the weather. It’s at 680 cycles and in better shape battery wise than my 2016 6s Plus.
What other iOS device than the 6s/6s Plus had the mega-drain thing where you can watch the percentage plummet from 100% to 1% or so in a matter of 15 minutes even though it has hours of juice left? It did this crap when it was new, so blaming new OS versions doesn’t cut it. This is no ancient legacy device, we’re talking about an iOS 14 compatible iPhone here.
iPhones have always had progressively worse battery life on newer versions of iOS. iPhones planned obsolescence conspiracies are based around it. Trust me I wish they didn't exist but they do...
Blaming the OS doesn't cut what? Metal level software like iOS has a direct correlation on battery life. This is no different then your usage of the software, play a game it uses more, turn it off it uses less. How do we get so many threads directly blaming the OS for battery problems yet they dont apply here?
Initial reviews of the iPhone 6S and 6S+ echo my own experience of solid battery life. Initially I was throughly impressed when compared to my aging iPhone 5S at the time. Somewhere around the mid point of iOS 10 is where I noticed I couldn't make it an entire day (wake to bed) without charging somewhere in there. Replacing the battery had little to no effect on battery life. Again just google iPhone 6S+ review, look for iOS 9 and find the battery section, I was going to link some but what's the point?
I still use an iPhone 6S for testing purposes and I get 4-6 hours of usage (which sucks but is serviceable)...
Using console shows how its hardware is being shoehorned into all the various processes that weren't in iOS 9. Whether it contributes to the problem or not (it does obviously) its still there. None of which processes can use low power cores since it doesn't have them.
Geekbench is also a good indicator of the state of things. The iPhone 6S is ~3x slower than my 11 Pro Max. Keeping in mind the SoC isn't as energy efficient either so round that up to 4x to be conservative. Another way to word that is it takes 4x the energy to accomplish the same task.
Its not an ancient devices however it is a device that hasn't been sold for nearly 2 years using 5 year old hardware which is a very long time in the tech space. The fact it runs iOS 14 means the same thing as me saying my 2011 thinkpad in my sig runs Windows 10....not much...
Regardless we know your 6S+ can't actually discharge a ~10wh battery in 15 minutes due to physics. And you know there is hours of life left when it shuts off like you mentioned.
That leaves what I said with the load on the battery causing it to dip below its shut off threshold on a bad battery (or cheap 3rd party battery). Again the explicit reason Apple went down the battery performance CPU throttling road (throttle load to prevent voltage dips that cause premature shutdowns).
Like my 6S a new battery should make it usable again however battery life will still suck on iOS 13 or later due to the demand of the OS and features its frameworks allow 1st and 3rd party apps.
