Guys, seriously, my battery health was 96% in jun, and now 88%…
The optimized charge does not work since my iPhone Xr (now i’m on 12), and I can’t even put my phone to charge at night before sleep because in the morning the screen freezes (all black)
I get this phone in jan/2022 (he’s on warranty)
In my experience I had a similar, but not as drastic time on betas. I went from 98% to 92% during iOS 15 on my release iPhone 12.
My battery habits were leaving it charging over night with optimised on.
Also I would use a Belkin wireless charger, bought from Apple, so the phone got a little hot.
I then set up an alarm/shortcut which, when I charged my phone once a day and it hit 100%, I unplugged it. I’ve stopped using wireless charging pads and charging all through the night. If my phone drops in the day to 30% I charge it up as and when I need it, keeping the drain out of the red.
This dramatically stopped the drop in health and around March time when it went to 89% I got the battery replaced. (Paid)
My phones health is still at 100%, and I’ve been using it through the whole of ios16 with the same method - but that could also just mean ios16 has been a better beta experience on my phone.
Take from that what you will. And I’m not saying my behaviour is right, it just works for me and seems to be working very nicely for my phones health. I suppose I’m saying, you’re not alone and these things can happen on betas 👍🏼