I go on hiking trips for a few days at a time. I do have a 10,000 mah battery I can carry to charge from but it's extra weight. Got to save every ounce you can.I've never been away from a charger long enough for me to notice. If I'm near one, I charge to 80%, and that will always carry me til the next time I'm near a charger to charge til 80% again. Repeat ad nauseum.