Stop my iphone 11 device from shutting down and restarting
Stop restarting and shutting down my iphone device
iPhone 11, iOS 18
Question marked as
Your battery is most likely failing.
Batteries degrade over time with usage due to chemical aging, that's just how they work.
You can expect about a 1% drop per 50 charge cycles with average use on an iPhone. This is an approximation, that is why it may be plus or minus a few percent on a month to month basis.
Apple recommends replacing it when the battery health reaches 80%. To check your battery health, go to Settings > Battery > Battery Health.
iPhone Battery Replacement.
iPhone Battery Replacement - Apple Support
About Lithium Ion Batteries
iPhone battery and performance - Apple Support (IN)