I bought a new 1st gen SE back in 2017 or so which served me very well for many years.
By 2022 the battery had noticeably degraded so I sent it off to Apple for replacement. Instead of replacing the battery, they sent me back a replacement phone.
Within less than a year this replacement was far worse than my original phone. It would eat 20-30% of battery just checking news/weather for 20 minutes or so in the morning. It would crash and restart (or crash and lose all charge completely) at any point below about 30% battery health.
But the strange thing is that the battery health diagnostic was still very high throughout this year - around 90% or so.
Anyway I successfully argued for Apple to send me a replacement replacement. I've had this one for about four weeks and it's already doing the same things.
Have I been sent two duds in a row or is this just the 1st gen SE experience these days with newer software?
When my SE1 battery was giving trouble, which started in the mid- to high-eighties percent Battery Health, the phone assured me that the condition was good enough to support normal function. Finally, with random power-offs and high drain in normal use - in other words, hopelessly incapable of supporting normal function - I replaced it myself and all the problems were fixed.
Battery life is not as good as when it was new, but I don’t know why that is. I think it’s a common experience, though. Ageing components? Running later versions? Who knows.
The fact that mine is good proves that the phone is still viable, so I’m guessing that something is wrong with yours - perhaps a bad battery.