I have started seeing TV ads for rechargeable hearing aids.  There seems to me to be a major problem with that idea in that you can't hear with them while recharging?  Years ago I had some rechargeable 675 batteries that worked but ran down before the end of my day.  It was inconvenient but in that case I could just change batteries.  With it built in to the aid it leaves you without use of the aid until recharged.