In iOS 13, by default, your iPhone will enable "Optimized Battery Charging." The new option will automatically stop your iPhone from charging when it hits 80 percent. At that point, the iPhone will act as if it at 100 percent, doing its best to conserve the percentage. Based on your habits, usage, and the alarm settings, right before you would typically start using your phone, it will begin charging again, this time letting the phone get to a full 100 percent.
The setting is excellent for the preservation of your battery. Instead of Apple's previous method of underclocking the CPU, you'll experience no decrease in performance. You can continue charging your iPhone overnight, and your battery will be less stressed out since it will only start charging to above 80 percent once it thinks you're about to use your iPhone. It uses machine learning to figure out your routines and habits, as well as alarm data and other scheduled settings.
It Can Be Entirely or Temporarily Turned Off?
The problem is, you might not want your iPhone to do what's described above. Depending on how hectic your schedule is, your iPhone could take some time to figure out when you routinely use your device, which means you'll likely wake up with your iPhone closer to 80 percent instead of 100 percent. To fix this, you will need to turn this feature off.
To speed your next charge up for more power faster, open Settings, select "Battery," choose "Battery Health," then select the toggle next to "Optimized Battery Charging."
A pop-up will appear with three options. Select "Cancel" if you've changed your mind. Otherwise, you can use "Turn Off" to disable it entirely or "Turn Off Until Tomorrow" if you just want to fast charge during the night only once.