Hearing Aid Batteries
Hearing aid batteries are most often made of zinc-air
batteries. The difference between these batteries and regular ones is
that air acts as the primary cathode reactant. Since it is using air
as the reactant, instead of alkaline, silver or mercury in standard
batteries more zinc (fuel) can be put into the battery which allows
it to last up to five times longer than a comparably sized regular battery.
Zinc-air batteries are especially suited for hearing aid batteries
because they last a long time, which is important because most hearing
aids are continuously on for an average of 16 hours a day. They also
completely discharge with almost no change in voltage until the battery
is exhausted, which means that volume and power levels will remain constant
until it is time to replace the battery.
Another advantage to using zinc-air hearing aid batteries is that zinc
is non-toxic and very cheap. The price usually stays at about $1000
per ton of zinc. There is almost no risk of these types of batteries
blowing up due to built up pressures inside or heat because they already
contain many holes to allow the zinc to react with air. The safety and
efficiency make these great batteries for smaller applications that
require low, constant power.