When a hearing aid unexpectedly stops working, the immediate question is whether the battery has failed or if there is a problem with the device itself. Reliable battery function is paramount for consistent hearing performance, but the small size of zinc-air cells makes their power status difficult to determine by simple visual inspection. Knowing how to accurately confirm the charge level before replacing a battery or seeking a device repair can save time and prevent unnecessary frustration.
Dedicated Hearing Aid Battery Testers
The simplest and most accessible method for checking battery power involves using a dedicated hearing aid battery tester, a compact device designed specifically for these small cells. To use one, the battery must be placed onto the tester’s contact points, ensuring the positive (+) side aligns correctly with the indicated terminal. These testers work by measuring the battery’s voltage while applying a small electrical load, which provides a more accurate reading of its capacity under working conditions.
The results are typically displayed in an easy-to-read format, such as a color-coded indicator or a digital screen. Color indicators often show green for a full charge, yellow for a weakening battery, and red for a depleted cell that requires immediate replacement. Digital readouts offer a more precise percentage of remaining life, which is helpful for deciding if a battery can last through a full day of use.
If testing a brand-new zinc-air battery, it is important to wait before placing it on the tester. Zinc-air batteries are activated when the factory seal tab is removed, allowing atmospheric oxygen to enter the cell and initiate the chemical reaction. This process, known as “airing up,” should be allowed to complete for a few minutes to ensure an accurate voltage reading.
Using a Multimeter for Voltage Testing
For the most technical and accurate measurement, a digital multimeter can be used to determine a battery’s open-circuit voltage. This method requires setting the multimeter to measure direct current (DC) voltage, typically selecting a range such as 2 volts (V) or 20V, depending on the device. Hearing aid batteries are nominally rated at 1.45V, so a setting slightly higher than this nominal value will provide the best resolution.
The positive (red) probe of the multimeter should be placed on the positive side of the battery, which is the flat surface, while the negative (black) probe touches the opposite, slightly raised side. A new, fully activated zinc-air battery should register an open-circuit voltage between approximately 1.4V and 1.45V. Readings much lower than this range indicate a battery that has been partially depleted or improperly activated.
The most important data point is the minimum acceptable voltage, which signals the need for replacement. While a battery may power the hearing aid above 1.25V, performance may begin to decline when the voltage drops below this level. If the reading is significantly below 1.2V, the battery is likely exhausted and will not provide enough power for the device to function correctly.
Checking Battery Performance Via the Hearing Aid
It is possible to assess battery function without any external tools by observing the hearing aid’s performance and listening for specific auditory cues. Many modern devices are programmed to provide a low-battery warning, which may be a series of distinct beeps, chimes, or even a voice prompt. These warnings are designed to give the user a short window of time to replace the power source before it completely fails.
A simpler check is to place the hearing aid in the palm of your hand and cup your hand around it, creating a closed chamber. If the battery is working, the microphone will pick up the sound of its own amplified output, causing acoustic feedback, which sounds like a high-pitched squeal or whistle. If you hear this distinctive feedback sound, the battery has enough power to run the device’s amplifier and is likely still functional.
If a new battery does not seem to work, or if the hearing aid cuts out unexpectedly, ensure the zinc-air activation process has completed. After peeling off the protective tab, allow the battery to sit exposed to the air for at least one to five minutes before inserting it. This allows the zinc and oxygen reaction to reach the necessary voltage level to sustain the power demands of the device.