By Yishane Lee

Hearing aid batteries are the perfect little stocking stuffer for the hearing aid wearers on your list—or if you’re a hearing aid wearer yourself, you should request from Santa!

Hearing aids use miniature zinc air button cells, which represent a huge improvement over their mercury predecessors—not least because the mercury ones were toxic! They also last twice as long, are environmentally friendly, and are less expensive.

The battery is activated when the sticker tab is removed, and exposing the cell to air oxidizes the zinc and powers the battery. Wait 30 to 60 seconds for the cell to become fully activated before placing the new battery into the hearing aid. This helps maximize the battery’s life.

The size of these button cells are universally standardized and the sizes are color coded for convenience, whether they are disposable or rechargeable. Common sizes are size 10 (yellow) and size 312 (brown). How long they last depends on use, but generally size 10s last three to five days, and size 312 about 10 to 15 days.

The key is making sure the seal that activates the battery remains intact. If it becomes damaged and air reaches the cell, activating the zinc, the battery will eventually drain. (And then you may find yourself in a foreign country looking for a pharmacy that sells hearing aid batteries—always bring spares when traveling!) Besides pharmacies, your hearing healthcare provider, warehouse stores, and online retailers all sell batteries.

Battery shelf life is several years, provided you store them at room temperature and keep them away from heat and humidity, which can affect the seal. Always store and transport in their original packaging. Carrying batteries around in your pocket or handbag can also damage the seal, and your keys or other metal objects can inadvertently short-circuit them.

Open up the battery compartment when you remove them and shut them off (newer models do this automatically for you), so they are aired out overnight. Exposure to moisture is another risk for zinc air batteries.

Remember: All batteries pose a serious health risk for children and pets if swallowed. Keep them out of reach and contact poison control immediately at (202) 625-3333 if they are ingested. Get more safety tips from the National Capital Poison Center.

And a note about recycling: Zinc is hazardous to the environment. So while many states do not require that hearing aid batteries be recycled, if you throw the batteries out with the trash, over time the harmful chemicals will be released. Look for battery recycling bins at large grocery stores and drugstores. Hearing aid retailers and hearing providers also may accept used batteries as well. The Big Green Box and Battery Solutions will recycle your batteries (and other electronics) for a fee. See Earth911 and Call2Recycle for battery dropoff locations and other resources.

Read more about batteries, including rechargeable and proprietary options, as well as choices for cochlear implants.