It’s not how long you charge your iPhone that matters, necessarily. It’s how long you wait to charge your iPhone and then how fully charged you insist it be before unplugging your charger.
In order to keep your phone’s Li-ion battery in good working condition, it helps to maintain a phone charge of between 40 and 80 percent at all times.
You can damage your phone’s battery if you wait for it to dip down to zero percent and then hastily charge it to 100 percent. A better plan of attack is to provide it with mini charges throughout the day that ensure it stays within the 40 to 80 percent battery zone.
And there are other steps that Apple recommends you take in order to prolong your iPhone’s battery life.
Always update to the latest software, for starters. And then adjust your screen brightness and use W-Fi. To dim its brightness, Apple suggests taking the following steps:
Open Control Center and drag the Brightness slider to the bottom.
Auto-Brightness adjusts your screen to lighting conditions automatically. To activate it, go to Settings > General > Accessibility > Display Accommodations and set Auto-Brightness to On.
Another important step you can take to prolong your battery is to enable low power mode.
According to Apple: “Introduced with iOS 9, Low Power Mode is an easy way to extend the battery life of your iPhone when it starts to get low. Your iPhone lets you know when your battery level goes down to 20%, and again at 10%, and lets you turn on Low Power Mode with one tap. Or you can enable it by going to Settings > Battery.”
Once you enable low power your screen brightness automatically dims and other battery-draining features are temporarily disabled to save you battery.
It’s not necessary, or even recommended, that you charge your iPhone fully each time — but keeping these tips in mind will help prolong your battery’s life.