RC, mine have a charger unit with its own battery inside. I can get two to three days on my aids, and then the charger can give me two or three more full charges. Ten days easy and two weeks of charge likely (although I haven't had to test that.) And the charger plugs to a USB.
On long fishing trips, I carry a small folding solar panel. It recharges my AA GPS batts as well as my hearing aid charger. Goal Zero brand of panel.
