Hearing aids are tiny, amazing devices that can provide a world of sound to individuals with hearing loss. Hearing aids use power from a battery to make it's various parts function. From the microphone, to the amplifier, to the receiver, these parts rely on a battery to function.
Even though rechargeable hearing aid batteries are becoming more and more popular, some hearing aids, especially custom hearing aids, still use disposable batteries. How do these disposable batteries work? The science is very interesting, but let's start with the basics!
Disposable hearing aid batteries come in 4 sizes, ranging in size and battery life. From small to large, they are named size 10, 312, 13, and 675. Size 10 are marked with a yellow tab, size 312 are marked with a brown tab, 13 with an orange tab, and 675 with a blue tab. Usually, very small hearing aids (Invisible in the canal, IIC, or completely in the canal, CIC) will use the size 10 battery, whereas larger hearing aids (Traditional Behind the Ear) use the larger 13 or 675 battery. The size 312 is the most popular size, and is often used in most Receiver in the Ear hearing aids and custom fitting hearing aids.
Disposable hearing aid batteries are considered Zinc-Air batteries. That's because there is Zinc inside the battery to make power. Batteries provide power to a hearing aid by using this Zinc inside the battery and oxygen from the surrounding environment. Zinc is ‘oxidized’ by the oxygen around you, and this chemical reaction produces zincate. When this chemical reaction happens, power is made, which is then provided to your hearing aids! When you pull off the tab from your batteries, air rushes into the battery and starts the reaction.
It is important to remember that whether you use the battery or not, once you pull off the tab, the battery starts working, so make sure you only pull off the tab when you’re ready to put the battery into the hearing aid. I recommend leaving the battery out for one minute after pulling off the tab to get chemical reaction process started.