Batteries are batteries. For the body aids yes they were bigger (with mine they looked like a Double A battery if I remember right). I don't remember how long a battery lasted though. They came in little packs of 2- red box with a red wrapper you could peel off the battery lol, but the HA only used one.
I get that with the BTE, the body aid was a backup- but what happened if both batteries were dead... D-E-A-D dead?
