Do I charge my iPhone daily? No, typically. Normally, I charge it to 100% and use it until the device automatic shut-off, which it does after hanging onto 1% for quite a while.
Launch day iPhone X. Current battery health is ~83%. Total charge cycles >880. Last charge (100% -> off) spanned ~24 hours, including a couple hours of GPS usage, navigation as well as workout tracking (i.e., assisting Watch).
I have used everything from the Apple 5W charger, Apple 10W charger, Apple 12W charger, Amazon Basics 30W GaN charger, Mophie Powerstation battery pack, and Anker PowerPort Wireless 10W Qi pad.
Long ago I used to keep my iPhone 5 plugged in continuously- and the battery swelled and pushed off the screen.
This is one of the few exceptions when charging routine (or rather lack thereof) can be significant — sorry to spotlight you. Basically, it’s not whether you charge the battery past 80% or below 20%, for example. The problem is if the cells remain in either of those “extreme” states for weeks or more. To elaborate a little further, if the ions are crammed near one electrode or the other, it creates pressure. Therefore, a battery cell has the least strain when the ions float in the middle (i.e. ~50% charge). As most of us have learned, excessive/extreme heat also creates additional pressure. This is why you’ll often see instructions for batteries/battery-powered devices to store the battery at 50% - 60% charge, disconnected from the device, in a cool and dry location if expected to be unused for a significant period. The slightly higher charge level is to account for an inevitable slow discharge. The dry aspect is, of course, primarily to help prevent corrosion.
Ultimately, as long as you keep devices/batteries away from high heat and active or stored properly, battery degradation is out of your control. Well… You can also hope to win the “battery lottery.”
