I have worn both the original Fitbit Charge HR and the more recent Charge 2 daily for the past few years. Aneceotally, because the watch isn't really water res

I have worn both the original Fitbit Charge HR and the more recent Charge 2 daily for the past few years. Aneceotally, because the watch isn't really water resistant (not least because the bands bubble if they get wet often), I have had it run out twice in that time and both times I was on holiday somewhere with no power. Because you are unlikely to actually wear it in the shower, just leave the charger permanently in your bathroom and get in the habit of taking it off and putting it on the charger when you shower. Even if you forget for one or two days it will almost always be sufficiently charged.