iPhone 15 shuts down at 20% battery and shows 1% on restart

kokila258 wrote:

I buy it used from someone and that guy said original battery replaced.

That's unfortunate. As I suspected, your phone doesn't have an authentic Apple battery, so Apple won't touch your phone. You can go to an iFixit type store and see if they can replace the failing battery in your iPhone. It too won't be authentic, but it likely will work better than the clearly defective one in your phone currently.

Sounds like you have an issue with the battery in your iPhone. Open Settings > Battery > Battery Health - what is shown there and how many cycles?

kokila258 wrote:

My iPhone 15 shuts down automatically when the battery is above 20%. When I turn it back on, it shows only 1% battery. This has happened repeatedly.

That means your battery is failing. The only solution is to have the battery replaced with a good quality battery.

Are you the original buyer of the phone or did you buy it used from someone/someplace? It would appear you don't have an authentic Apple battery in your phone. And if that is the case, Apple typically won't touch a phone with non-authentic parts in it.

The original battery might have been replaced, but the replacement was not a genuine Apple battery. That is why the Maximum Capacity is "Unverified".

Other Battery settings may or may not be correct as well.