Do you know all this about hearing aid batteries?

Do you know all this about hearing aid batteries?

Hearing aids are high-precision medical devices. Nowadays, hearing aids have been developed to be more refined and compact. Most hearing aids use dedicated zinc air button batteries with a voltage of 1.4-1.45V. Models are divided into the following types according to size and capacity:

A675 is the largest volume of button batteries for hearing aids, and is often used in mid- and high-power behind-the-ear and eyewear hearing aids.

A13 battery is the same thickness as the 675 battery, but with a smaller diameter, it is commonly used in mid- and low-power behind-the-ear or in-the-ear hearing aids.

A312 battery has the same diameter as the 13 battery, but it is thinner. It is often used in the ear, ear canal, or part of the middle- and low-power hearing aids.

A10 battery is the same thickness as the 312 battery, but with a smaller diameter, it is often used in ear canals and deep ear canals.

A5 is currently the smallest hearing aid battery with less stored power. It is rarely used in domestic hearing aids.

 What are the characteristics of zinc air batteries?

Zinc air battery is a disposable chemical power source using zinc metal as the negative electrode, oxygen in the air as the positive electrode deactivator, and a strong alkaline aqueous solution as the electrolyte. Due to the small size of the hearing aid and the long continuous working time, a battery with a high capacity per unit volume is required. At present, except for zinc-air batteries, the specific capacity of other batteries is relatively low. The use of low-capacity batteries means that users need to replace the batteries frequently, causing inconvenience in use.

About battery voltage

The normal open-circuit voltage of a zinc empty battery is 1.4-1.45V, but if the tape is just removed (there is no oxygen in the battery at this time, and it is in a dormant state), or the ambient temperature is too low, the voltage is much lower than 1.4V. When the hearing aid works normally, the battery voltage is generally between 1.2 and 1.3V. When the voltage drops below 1.1V, the hearing aid is difficult to work normally.

Zinc air battery operating temperature and capacity drop rate

The working temperature range is -10-50 ℃, and the annual capacity reduction rate is 3% under good storage conditions.

Distinguish between zinc empty battery and ordinary button battery

Zinc air batteries are similar in appearance to silver-mercury button batteries. There are two main differences when looking at the difference: one is that the positive side of the zinc air battery has a small air hole, but the silver mercury battery does not; the other is that the zinc air battery has air holes The open circuit voltage is 1.4V when it is unblocked (the open circuit voltage is lower when the stomata are closed and higher when the stomata are unblocked), while the silver-mercury battery is 1.5V.

How to calculate the battery life?

The actual battery use time is related to the hearing aid model, the degree of personal hearing loss, the daily use time, and the volume adjusted during use. In general, the larger the battery used in a hearing aid, the lighter the hearing loss, and the longer the battery can be used. Can be estimated using the formula:

Total hours of use = Battery capacity (mAh) / Working current (mAh)

Number of days used = Total hours used / Average hours used per day

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