I did not mean to offend anyone about the water resistance…rather I wished to
discuss moisture and reasons my modern aids are so susceptible to it… So far
I learned that:
a.) I should use a proven drying system at night such as the dry-n-store.
b.) The sweatbands discussed here are an excellent preventive measure for where I
know I’ll be sweating ie…riding a bike, working in the yard.
c.) The aids need air for the zinc-air batteries so they cannot be water tight.
d.) Sealing the shell does not necessarily solve the problem.
Still a lively a discussion on hearing aids and moisture. I still contend the manufacturers are getting paid the big bucks to design some moisture resistance into the products 
I don’t see any offense being taken. Now, a, b, and c above are all correct. d is slightly different though … sealing the shell would work as far as keeping out moisture … except the common batteries need air to work. As Jay_man pointed out, there is the option of rechargeable batteries, they do exist, and they do not need air to produce current. However, as small as the batteries are, they do not last very long, and you would have to carry spare batteries with you all of the time just in case. And once you use the regular battery, why just throw it out before it dies … or if extra rechargeable batteries, they lose power over time and you’d be recharging two sets of batteries every night. Also, rechargeable batteries that I’ve used in other electronics do not retain full power until they die, but lose power more gradually. A battery that loses power gradually results in static in hearing aids when they hit the point of not being quite strong enough to support the power demanding hearing aid.
Moisture is also damaging to the electronics in the aids, not just the batteries. That is where the Dry n Store comes into play. It actively dries the hearing aid by use of a desiccant PLUS warm air being circulated through the aid to dry it out. The battery is left outside the box and is not affected by this. I also questioned my HI dispenser when he wanted to sell me this dryer for $100 … yeah right, more money in his pocket. My wife was more realistic though, she said the aids cost plenty, if 100 bucks would extend their life, let’s do it. I haven’t looked back since and strongly suggest the use of the Dry n Store now … it is NOT a rip-off. It stopped my aids going back consistently for repair.
This past weekend, I was out at a local park getting quite sweaty running around on a hot day setting up dog races. A couple of times, I did get a low battery warning. I removed my aid, dried my head as best as possible, and dried the battery off and put it back in the aid … I was back in business with the same battery all day and still have that battery in today. So if moisture kills the battery, just don’t toss it … it may still be good if caught early on and dried off. I also think it’s time for me to look into those socks as I’ll be getting more involved with dog racing this year, a new hobby for me. I hope to have my own Whippet some day soon. In the meantime, I’m working with a couple of breeders racing their dogs, boxing and catching them, as well as setting up the track.