I feel that the battery is always not fully charged?? It turns on this function~

According to the official tip: Apple lithium-ion battery uses the fast charging method to quickly reach 80% of the power, and then switches to the slow trickle charging until it is fully charged. That's why the charging speed will slow down after 80%.

This combined charging process of fast charging and trickle charging can make the device have enough power to go out in a short time, and also give full play to the battery performance and prolong the service life of the battery.

When the battery exceeds the recommended temperature, the software may limit charging after the battery reaches 80%.

In case of such a situation, it is suggested that the small partner should go to the service center in time to check the battery health. If the battery is aging, it is suggested that the battery should be replaced in time.

In IOS 13 and later, Apple has added the function of "optimizing battery charging".

Its role is to reduce battery loss and extend battery life by reducing the time the iPhone is fully charged.

When enabled, the iPhone will delay charging more than 80% in some cases.