Hearing aid battery
A hearing aid battery is a battery that is specially designed to supply power to hearing aids . The usual design is that of a button cell , which is why it is also counted among the micro batteries.
Modern hearing aid batteries are mostly non-rechargeable zinc-air batteries . The batteries therefore often have the (manufacturer-specific) designation ZL for zinc-air or ZA for zinc-air . Zinc-air batteries are characterized by their very high energy density and their suitability for high power requirements. The latter means that the voltage remains almost constant even with relatively high currents until the end of the discharge (so-called "Flat Discharge Curve"). In order to prevent the premature entry of air and the drying out of the battery, which leads to a loss of usable capacity , the air holes on the positive pole of zinc-air batteries are masked with a protective film. This must be removed before inserting the battery into the hearing aid. Depending on the type and manufacturer, the battery begins to deliver power several seconds to a few minutes after activation. The self-discharge of zinc-air batteries with attached protective film is around 3% per year. When activated (protective film removed), zinc-air batteries can only be stored for a limited time and should be used as soon as possible.
In the past, mercury oxide-zinc batteries were predominantly used in hearing aids . Today zinc-air batteries still contain approx. 1 to 3% mercury . But there are also manufacturers who completely do without mercury. In the United States , hearing aid batteries containing mercury are already banned in some states . Today, rechargeable hearing aid batteries ( accumulators ) are also available. These are nickel-metal hydride batteries designed as button cells . However, due to the trend towards ever smaller hearing aids and thus ever smaller batteries, these rechargeable batteries are rarely used; they have to be recharged after a short period of time.
The sizes of hearing aid batteries are coded by a number (type) and a color scheme. The color of the protective film on the zinc-air batteries follows the mentioned color scheme for almost all manufacturers. A corresponding color mark is also often attached to the outer packaging. In addition to the names standardized by the International Electrotechnical Commission (IEC) and the American National Standards Institute (ANSI), there are also a large number of manufacturer-specific names for zinc-air hearing aid batteries of these sizes.
Number / type | Color scheme | IEC (zinc-air) | ANSI (zinc-air) | Renata | Varta | Duracell | Diameter × height | Capacity (reference value) | tension |
---|---|---|---|---|---|---|---|---|---|
675 | blue | PR44 | 7003ZD | ZA675 | V675A | DA675 | 11.56 mm x 5.33 mm | 650 m Ah | 1.4V |
13 | orange | PR48 | 7000ZD | ZA13 | V13A | DA13 | 7.80 mm x 5.35 mm | 310 mAh | 1.4V |
312 | brown | PR41 | 7002ZD | ZA312 | V312A | DA312 | 7.80 mm x 3.45 mm | 180 mAh | 1.4V |
10 | yellow | PR70 | 7005ZD | ZA10 | V10A | DA230 | 5.80 mm x 3.55 mm | 100 mAh | 1.4V |
5 | red | PR63 | ZA5 | 5.80 mm x 2.16 mm | 35 mAh | 1.4V |
The currently most common types are 13 (orange), 312 (brown) and 10 (yellow). As the miniaturization of hearing aids progresses, the smaller sizes are increasingly being used in BTE hearing aids (behind the ear). Type 675 (blue) continues to be used for powerful (high-performance) BTE hearing aids and cochlear implants . Type 5 (red) is increasingly being used in modern, particularly small ITC hearing aids (English In The Canal "in the ear canal") and CiC hearing aids (English Completely in the Canal "disappearing in the ear canal"). However, these are still very poorly used.
literature
- David Linden and Thomas B. Reddy (Eds.): Handbook of Batteries . 3. Edition. McGraw-Hill, New York 2002, ISBN 0-07-135978-8 .