This morning when I picked up my iPhone from it's Qi charger, I was greeted by a new message - Optimized Battery Charging Enabled.
I was fortunate enough to be get my iPhone 11 Pro on launch day, and in the six months of ownership, today was the first time I saw the message. I had to go look this feature up. At first, I got is confused with the Peak Performance Capability - the feature that throttles iPhone performance when a battery becomes chemically degrades. But, this was something different. While all batteries degrade over time, the Optimize Battery Charging feature is intended to prolong the useful life of the battery. In the iOS 13.0 release notes, Apple states that "optimized battery charging to slow the rate of battery aging by reducing the time your iPhone spends fully charged."
Optimized Battery Charging is a pretty niffy feature. To prolong the useful life of your iPhone's battery, iOS will only charge the battery to 80%. The AI features of the A13 Bionic chip works out how you charge your iPhone and then only charges the last 20% so that it will complete charging just before you need it. For example, my iPhone will learn when I put it on the charger before going to bed and will charge it up to 80%. It will also work out when I get up in the morning and take it off the charger. Optimized Battery Charging will charge that final 20% just before I wake up.
When the iPhone is put on the charger, and the feature is enabled, a notification will appear on the lock screen letting you know that optimized battery charging is on. In a hurry and want to charge up to 100% right now? Tap and hold the notification and then tap the Charge Now option.
You can enable and disable the Optimized Battery Charging feature, and check the health of your battery by going to Settings > Battery > Battery Health.
For more information, you can read the About Optimized Battery Charging on your iPhone support article.