Hearing aid batteries are not all the same; compatibility depends on specific physical and chemical characteristics. Selecting the correct battery involves matching dimensions and understanding the technology, which maintains device performance and longevity.
The Critical Difference: Size and Color Coding
Disposable hearing aid batteries use a standardized system for easy identification. There are four primary sizes used worldwide: 10, 312, 13, and 675. Each size corresponds to a specific diameter and height, which is not interchangeable between different hearing aid models.
To simplify this process, a universal color-coding system is employed across manufacturers. Size 10 batteries are coded yellow, Size 312 are brown, Size 13 are orange, and Size 675 are blue. This visual system allows users to purchase the appropriate battery without needing to memorize the numeric code or precise dimensions.
The physical size of the battery is directly related to the power needs of the hearing aid it supports. Smaller batteries, like Size 10, are used in the most discreet devices, such as completely-in-canal (CIC) models. The larger Size 675 batteries are reserved for high-power devices and cochlear implants, which require a greater energy capacity. Your specific hearing aid model dictates the required size, and inserting an incorrect size can damage the device’s battery compartment.
Understanding Zinc-Air and Rechargeable Options
The most common chemistry for disposable hearing aid batteries is zinc-air, which offers a high energy density for their small size. These batteries are unique because they use oxygen from the surrounding air as a reactant in the electrochemical process. This design frees up internal space within the cell, allowing for more zinc and a greater capacity compared to other chemistries.
A factory-sealed adhesive tab covers the air holes on the battery, keeping it inactive until use. Once this tab is removed, oxygen enters the cell, initiating the chemical reaction that generates power.
Zinc-air batteries are favored because they provide a stable voltage output, typically around 1.4 volts, throughout most of their discharge cycle. This stable output is essential for consistent and clear audio amplification.
Rechargeable options have become increasingly prevalent in modern hearing aids, contrasting with disposable zinc-air cells. These devices use integrated power sources, most commonly lithium-ion batteries, built into the hearing aid itself. Rechargeable hearing aids eliminate the need for frequent battery replacement, though the battery unit is not interchangeable. The power source is recharged by placing the entire device into a charging unit, offering a convenient alternative for continuous daily use.
Usage Factors That Affect Battery Life
The actual duration a hearing aid battery lasts can vary significantly, even between two identical batteries, based on how the device is used. One of the main factors is the setting of the hearing aid volume. When the volume is set higher, the device requires more power to amplify the sound, leading to faster battery drainage.
Modern hearing aids often include power-intensive features that increase consumption. Functions like Bluetooth streaming, which allows audio to be sent directly from a phone, or advanced noise reduction algorithms demand a higher electrical current. The more frequently these features are engaged, the shorter the battery’s lifespan will be.
The acoustic environment itself also influences how hard the hearing aid must work. In a noisy setting, such as a crowded restaurant, the device must continuously process and filter complex sounds, increasing its power draw.
Environmental conditions like temperature and humidity can also impact performance. High heat or excessive moisture can affect the zinc-air chemistry, potentially reducing the battery’s effectiveness and life.
Proper Storage and Handling Practices
Correct handling of zinc-air batteries starts before they are placed into the hearing aid. Batteries should remain in their sealed packaging with the protective tab intact until needed. This tab prevents oxygen from entering the cell, maintaining the battery’s shelf life, which can be up to three years under proper conditions.
Once the tab is removed, wait one to two minutes before inserting the battery into the device. This brief “air-up” time allows sufficient oxygen to enter the cell and fully activate the zinc-air chemistry, ensuring optimal voltage for reliable power. Reattaching the tab after activation does not stop the discharge, so the battery will continue to drain even when not in use.
For storage, batteries should be kept in a cool, dry place, ideally at room temperature (10 to 25 degrees Celsius). Keep them away from metal objects, such as keys or coins, which can cause a short circuit if they contact the battery’s terminals.
When the hearing aid is not being worn, opening the battery door is a simple action that breaks the electrical connection and prevents unnecessary power drain.