Rechargeable batteries are everywhere nowadays. Your phone, speakers, laptop... If it's made to be portable it most likely has a rechargeable battery. Rechargeable hearing aids are no exception, and many current models today utilize rechargeable batteries as well.
There's a new development every consumer who suffers from mild to moderate hearing loss should know about. New FDA guidelines will allow for over-the-counter hearing aids to be sold, which, in many cases, will eliminate the need for exams, office visits, and expensive devices.