I am also somewhat certain this drain is deliberate. Remember, apple was caught red handed a few years ago with the "slowing down old devices" thing. So the logical next step for them is to sabotage the next best thing to frustrate their customers to buy a new phone. Having used Apple since the model 3g (and having gone through all their tricks) I am seriously reconsidering any future apple products as this kind of bullsh*ttery does not make anyone feel special.