My phones have a setting specifically for this. It's called Battery Protection on Samsung. It stops charging when it gets to 85%. And on the newer phones it has a basic setting that cuts off at 85% and an advanced setting that sets the cutoff based on your particular useage patterns. So sometimes it could be 85%,snd other times it could 90-95%. It fluctuates. In any case, it's a smart thing to do especially if you anticipate using the phone for 3+ years. It's not as important if you're someone who gets a new phone every two years.