7 Never Turning It Off
This tip may sound counter-intuitive, but it’s true. While you shouldn’t let your battery die completely between charges, you should completely power off your device and leave it off every once in a while, according to Apple Genius Bar staff. Note that this is different than letting your device die — you’re not waiting for it to power off by itself.
Think of an iPhone like a car idling. Even though it’s not operating fully, it’s still running. And that, Apple says, can stress your iPhone’s lithium-ion battery. Periodically turning off your iPhone for a short time lets your iPhone’s software refresh and it can do wonders for your battery life. While you don’t have to turn it off every night, try to power-down at least once a week.