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A battery holder is one or more compartments or chambers for holding a battery. For dry cells, the holder must also make electrical contact with the battery terminals. For wet cells, cables are often connected to the battery terminals, as is found in automobiles or emergency lighting equipment. A battery holder is either a plastic case with the shape of the housing molded as a compartment or compartments that accepts a battery or batteries, or a separate plastic holder that is mounted with screws, eyelets, glue, double-sided tape, or other means. Battery holders may have a lid to retain and protect the batteries, or may be sealed to prevent damage to circuitry and components from battery leakage. Coiled spring wire or flat tabs that press against the battery terminals are the two most common methods of making the electrical connection inside a holder. External connections on battery holders are usually made by contacts with pins, surface mount feet, solder lugs, or wire leads. Where the battery is expected to last over the life of the product, no holder is necessary, and a tab welded to the battery terminals can be directly soldered to a printed circuit board. ==History== In the late 1800s patents were issued for consumer products like flashlights; patent no. 617592 dated March 1898 is for an early metal flashlight that accepted D batteries. Some early 1900s battery holders were often no more than a cardboard box with copper contacts. By the 1920s, battery holders used twin metal clips (like fuse holders) to hold the battery in place while making electrical contact. Patent no. 1439429 was granted in Dec., 1922 for an assembly with two spring arm clips, a small switch and a lamp assembly on the end of connected wires. The introduction of polypropylene in the 1950s and miniature batteries by Eveready allowed for the use of small plastic battery holders. These are still common in toys, decorations, and lighted or blinking items. In 1957, electric wrist watches gained popularity with the public. Battery holders developed in parallel with batteries over time; as battery package sizes shrunk so did the holders. In the 1980s, the first circuit board mounting lithium coin cell battery holders appeared in the form of patent no. 4487820 by the battery holder manufacturer MPD. The electronics industry now uses many surface mounted lithium battery holders or sockets. CR2/3A, CR1/2AA and CR123A batteries began in camera applications, but expanded into new markets like alarm systems, hand held computers, and keyfobs. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「battery holder」の詳細全文を読む スポンサード リンク
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