battery draining

Howdy! iOS 15.7.1 is not the latest iOS version for the iPhone 13. I would recommend updating first and then seeing if the problem persists. If it does, check your battery usage page in Settings to determine if there's any misbehaving apps. From there perhaps the root cause can be worked out.

Hope this helps!

I haven't had any issues with iOS 16.3.1, and no it is not currently possible to only update to iOS 16.3. Basically, some software you may install is "signed", which essentially means it has the developer's stamp of approval, and it allows you to install it. iOS updates work this way. iOS updates are signed for a while, and then they stop being signed. Once they're no longer signed you can no longer install that version.

So since iOS 16.3 is no longer signed, it is best to update to iOS 16.3.1. You can do this by opening Settings, clicking General, and then Software Update.

Hope this helps!

FIRST: The best practice is to charge overnight, every night, with Optimized Battery Charging turned on.

Your battery uses energy 24 hours a day; the only way to stop that is to turn the phone off completely. So it will use energy overnight if it isn’t connected to power, and the amount it will use depends on the apps you have and the settings for those apps.

raa3211 wrote:

but there are reviews that 16.13.1 also has issues , can i update only to 16.13 ? any how

There have been “reviews” for every one of the hundred or so updates for iOS that say the version has issues. Usually these are user issues. If you believe reviews like that you will never, ever, update any product, not just iPhones.