My 6s is about 2 1/2 years old and battery performance has been very good. I will normally leave my phone turned on and on silent at night and it will use 4 -5 % charge overnight. All of a sudden I went to bed one night with battery at about 98% charge and when I got up in the morning it only had about 2 % left. I charged to 100 % in less time than I expected, but ever since then I am getting only about half or less of the tiime on a recharge compared to what I would get before this happened. Does anyone have any idea why my battery performance has dropped so drastically all of a sudden? Thanks in advance for any responses.