We live in a world filled with gizmos and gadgets; most of these things require power. Many portable devices run on batteries. Hearing aids are no exception. Most hearing aids run on a battery of a very specific type: zinc-air. The zinc-air battery contains a highly conductive potassium hydroxide electrolyte and a zinc anode. When this combination is exposed to air by removing a small sticker from the back of the battery (uncovering a small inlet of holes), it produces electricity for a given length of time.
Even though zinc-air batteries seem like such simple little mechanisms—plug them in and go—there is actually quite a bit you should know about them…
Size Matters: The batteries used in hearing aids come in four distinct sizes: 10, 312, 13, and 675. The size used by a certain hearing aid varies according to the size of the aid and the power required to supply the appropriate amount of amplification. Size 10 is the smallest and 675 is the largest; the most common size is 312.
Color Coding: No matter what company produces the battery, each size is color coded for ease of use. Size 10 is coded yellow, 312 is brown, 13 is orange, and 675 is blue.
Battery Life: The smaller the battery is the shorter the battery life. Along the same lines the more power necessary for amplification, the larger the battery required to sustain power and the shorter the life may be. Size 10 batteries last an average of 3-5 days, size 312 last 5-7 days, 13 run for 10-14 days, and 675 can last up to a month depending on power needs of the hearing aid. To extend a batteries lifespan, it should be disconnected from the hearing aid (by opening the battery door all the way) when it is not being used.
Stickers: As mentioned above, removing the sticker from the battery is central in powering it up. It is significant to remember, however, that once the battery is “powered up” replacing the sticker will not stop the chemical reaction inside of it—even without use the battery will eventually go dead. So, keeping this in mind, only remove the sticker when you are ready to use the battery.
Activation Time: It is important to note that it can take up to a minute or more for a sufficient amount of oxygen to enter the battery and begin the chemical reaction. So, to maximize the life of the battery it should be given proper time to “power up” before being put into the hearing aid. If it is not completely activated before the first charge is put through it, the hearing aid may act intermittently or your battery life may be substantially shortened.
Mercury: Within the last few years, hearing aid batteries have been manufactured, by law, without mercury (though they can still contain trace amounts).
Safety Against Swallowing: These batteries can be toxic if swallowed. Keeping them in a safe place—away from pets and small children—is important. If they should happen to be ingested, please call your local veterinarian or poison control respectably. Please visit http://ww.poison.org/battery/ for specific battery ingestion hotline/poison control hotline numbers and for further information.
Storing Batteries: As mentioned, in the section above, it is important to keep your batteries in a secure location, they should also be stored in a cool and dry place. Do not store the batteries (or aids for the matter) in the bathroom, near any heat sources, in your car, or in the refrigerator (moisture from the fridge can actually be absorbed by the batteries and shorten their life).
Battery Warning: Most hearing aids have a built in alert to let you know when it’s time to change your batteries. For some it is a series of beeps, whereas other aids will speak to you. This warning is often issued approximately 30 minutes before the battery goes completely dead. This should give you plenty of time to get a fresh battery installed.
Disposing of Dead Batteries: Though hearing aid batteries no longer have more than trace amounts of mercury in them, recycling dead batteries is still the most environmentally responsible option for disposal. Many city halls, libraries, and Home Depot stores take dead batteries for recycling. Check with your audiologist for more battery recycling locations.
New Batteries: Batteries are often also available from your audiologist. Batteries purchased in the audiologists’ offices tend to be of higher quality, fresher, and less expensive than other locations. This location also offers the benefit of being able to get your hearing aid cleaned and checked at the same time—one stop shopping. New hearing aid batteries can also be obtained from any store that contains a pharmacy (Target, Wal-Mart, Walgreens, CVS, etc).
Expiration Date: Like other batteries, zinc-air batteries have an expiration date. This is usually located on the back of the package toward the bottom. If there is an unbelievable sale on hearing aid batteries, make sure to check expiration dates. Some stores may put their batteries on extra sale when they are getting close to expiring in order to clear inventory.
These are all the important basics of zinc-air batteries. Now you can responsibly keep your hearing aids powered up and ready to hear the world! If you have any additional questions, please consult your audiologist.
To learn more about hearing loss or hearing technology please visit www.affinityhearing.com today!
Sarah Nordberg, AuD is an audiologist at Affinity Hearing in Plymouth. She may be reached at 763-744-1190 for any questions. Affinity Hearing provides free hearing screenings and hearing protection consults to the general public.