iPhone 6s Plus shows 65% with only 2 hours usage time since last full charge. So, since unplugging it, so far within this time period I'm at 65% already. I'm not a heavy user and Background apps are all off. Isn't this a bit low of a percentage for just 2 hours of use? I have auto lock in 2 min and auto brightness on indoor at about 40% brightness. Any comments or is my battery in need of replacement?