Just got the iPhone 6s and this is my first iPhone. Previously were using the Nexus series, which their battery is total garbage. With Nexus 5, I need to charge my phone 3 times a day without doing much. It was so bad to the point that I basically plug it in at home at work or bring a charge with me at all time. Now with 6s I realize I only use about 30~35% of the battery a day. Should I plug in and charge at night though it is still 70% full or should I wait till it is almost dead? Now sure how it will impact the battery health.