The battery slider is missing after updating to iOS 18

I’m assuming you are referring to the Charge Limit enhanced feature that lets you choose charge limits in increments of 5 between 80% and 100%. That is exclusive to iPhone 16 models and I believe possibly iPhone 15 models on iOS 18. Your 14 Pro would not be eligible.

It appears to be software related and only for 15 and 16 iPhones models. I have a iPhone 14 Pro Max and it is not in the iOS 18 update for my phone. Maybe it will change over time Apple will release to the older models.

16 pro and Pro Max only

What battery slider?

But what battery slider? I’ve never seen a battery slider on any iPhone.

I have the 15 ProMax and I also do not have the battery charge slider. I wonder if it’s coming out later this year

In the iOS 18 update there is a slider so you can stop your battery from charging at a certain percentage to prevent premature battery aging. I.E you can stop at 90% 80% or 70% etc

I don't see it on my 13 mini either after update and restart.