For a few years in college, when I spent more time around smokers, I carried a lighter in my purse in case a friend or a desperate stranger needed to bum a light. These days, I like to re-create this helpful gesture by bringing a portable charger wherever I go. If anyone’s phone battery is low, I get to save the day — and, of course, keep my own devices from dying.As a writer on the powering beat, I have endless options in the rotation. But the one I usually reach for when packing a bag for the day is the Belkin BoostCharge Plus 10K.