Yeah, I agree that BH has more to do with cycles (and heat!) rather than how you charge.Now one year since purchase. 97% max capacity, 244 charging cycles.
For the first 5 months I charged with typical USB-C Power Delivery chargers to a 80% charge limit, but after realizing that almost all of my charging was overnight while I slept, and while I showered after workouts, I switched to 12 watt USB-A to USB-C charging to an 85% charge limit, hoping that will extend battery health - I intend to keep the phone for 2.5 years, so another 18 months.
My guess is that battery health has more to do with total charge cycles than how you charge, but I'll still keep on this way while I own the phone.
An example: for 5.5 years, my main iPhone was an iPhone Xʀ running iOS 12. It has been on higher percentages for the vast majority of its life, as I haven’t used it much and I like to keep track of battery life. I can’t do that when standby makes it drop, so whenever I saw that the battery percentage dropped too much on standby (and it did, its standby battery life is terrible on iOS 12. Not a bug or a stuck process, but a pretty consistent maybe 7-10% every 24 hours of standby. Since I didn’t use it much because I had an odd use case with it, it was on standby a lot. So I charged it when it dropped… a lot!
I charged it with a 5w charger exclusively (always to 100%), avoided heat, and never updated iOS. That’s all I did. After 5.5 years of being between 80-100 a LOT it has around 360 cycles with 89% health. Pretty good considering I pretty much did the opposite of what’s recommended.
I do think that battery health is irrelevant if the device is on its original iOS version (i.e., battery life will be just as good if you don’t update with 70% health than with 100%… I’ve tried), so I don’t worry.
But after that experiment? Now I care even less about charging limits. Always to 100%, I know it’ll be fine.
I’ve tested iPhones on good iOS versions with 1500-2200 cycles and they were fine, so I do think this is not an issue at all.
However, since I’m a light user I doubt I’ll see an iPhone with many cycles that I have used myself. The best I’ve used was an iPhone 6s with 60% health and 1400 cycles which still runs iOS 10. Battery life was like-new.
My current iPhone 16 Plus is new, and it’ll take years before I see a decent number of cycles. I think this might be interesting with about 800-1000 or more. Less than that and it doesn’t say much.