A watch battery or button cell is a small single cell battery An electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy. Since the invention of the first Voltaic pile in 1800 by Alessandro Volta, the battery has become a common power source for many household and industrial applications. According to a 2005 estimate, the shaped as a squat cylinder A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given straight line, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder. The surface area and the volume of a cylinder have been known since typically 5 to 12 mm in diameter and 1 to 6 mm high—like a button on a garment, hence the name. Button cells are used to power small portable electronics devices such as wrist watches A watch is a timepiece that is made to be worn on a person. It is usually a wristwatch, worn on the wrist with a strap or bracelet. In addition to the time, modern watches often display the day, date, month and year, and electronic watches may have many other functions, depending on how modern the watch is, pocket calculators A calculator is a device that is used for performing mathematical calculations. It differs from a computer by having a limited problem solving ability and an interface optimized for interactive calculation rather than programming. Calculators can be hardware or software, mechanical or electronic, and are often built into devices such as PDAs or, and hearing aids A hearing aid is an electroacoustic device which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sound for the wearer. Earlier devices, known as an "ear trumpet" or "ear horn", were passive funnel-like amplification cones designed to gather sound energy and direct it into the ear canal. Some cells larger than the dimensions above are also called button cells, but are less commonly used. Lithium cells Lithium batteries are disposable batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V to about 3.7 V, over twice the voltage of an ordinary zinc-carbon battery or alkaline cell battery. Lithium batteries are widely used in products are generally similar but somewhat larger; they tend to be called either lithium cells or batteries or coin cells rather than button cells.
Devices using button cells are usually designed to use a cell giving a long service life, typically well over a year in continuous use in a wristwatch. Most button cells have low self-discharge and hold their charge for a long time if not used. Higher-power devices such as hearing aids, where high capacity is important and low self-discharge less so as the cell will usually be used up before it has time to discharge, may use zinc-air cells which have much higher capacity for a given size, but discharge over a few weeks even if not used.
Button cells are single cells, usually disposable primary cells A primary cell is any kind of battery in which the electrochemical reaction is not reversible. A common example of a primary cell is the disposable battery. Unlike a secondary cell, the reaction cannot be reversed by running a current into the cell; the chemical reactants cannot be restored to their initial position and capacity. Primary batteries. Common anode An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID materials are zinc or lithium Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable. For this reason, lithium metal. Common cathode materials are manganese dioxide Manganese dioxide is the inorganic compound with the formula MnO2. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese. It is also present in manganese nodules. The principal use for MnO2 is for dry-cell batteries, such as the alkaline battery and the zinc-carbon battery. In 1976 this, silver oxide Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds, carbon monofluoride, cupric oxide or oxygen Oxygen (pronounced /ˈɒksɨdʒɨn/, OK-si-jin, from the Greek roots ὀξύς (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly from the air. Mercuric oxide A mercury battery is a non-rechargeable electrochemical battery, a primary cell. Due to the content of mercury, and the resulting environmental concerns, the sale of mercury batteries is banned in many countries. Both ANSI and IEC have withdrawn standards for mercury batteries. Mercury batteries were made in button types for watches and button cells were formerly common, but are no longer available due to the toxicity Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ (organotoxicity), such as the liver (hepatotoxicity). By extension, the word may be and environmental hazard 'Environmental hazard' is a generic term for any situation or state of events which poses a threat to the surrounding environment. This term incorporates topics like pollution and natural hazards such as storms and earthquakes of mercury Mercury , also quicksilver (/ˈkwɪksɪlvər/) or hydrargyrum (/haɪˈdrɑrdʒɨrəm/ hye-DRAR-ji-rəm), is a chemical element with the symbol Hg (Latinized Greek: hydrargyrum, from "hydr-" meaning watery or runny and "argyros" meaning silver) and atomic number 80. A heavy, silvery d-block metal, mercury is one of six chemical.
Cells have a metal can forming the bottom body, with a circular insulated top cap. The can is the positive and the top the negative terminal.
Cells of different chemical composition made in the same size are mechanically interchangeable. The composition affects service life and voltage stability. Using the wrong cell may lead to short life or improper operation (for example, light metering A light meter is a device used to measure the amount of light. In photography, a light meter is often used to determine the proper exposure for a photograph. Typically a light meter will include a computer, either digital or analogue, which allows the photographer to determine which shutter speed and f-number should be selected for an optimum on a camera A camera is a device that records/stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images. The modern camera evolved from the camera obscura requires a stable voltage, and silver cells are usually specified). Sometimes different cells of the same type and size and specified capacity in mAh are optimised for different loads by using different electrolytes, so that one may have longer service life than the other if supplying a relatively high current.
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Properties of different types
- Silver cells may have very stable output voltage until it suddenly drops very rapidly at end of life. This varies for individual types; one manufacturer (Energizer) offers 3 silver oxide cells of the same size, 357-303, 357-303H,and EPX76, with capacities ranging from 150 to 200 mAh, voltage characteristics ranging from gradually reducing to fairly constant, and some stated to be for continuous low drain with high pulse on demand, others for photo use.
- Mercury batteries A mercury battery is a non-rechargeable electrochemical battery, a primary cell. Due to the content of mercury, and the resulting environmental concerns, the sale of mercury batteries is banned in many countries. Both ANSI and IEC have withdrawn standards for mercury batteries. Mercury batteries were made in button types for watches and also supply a stable voltage, but are now banned in many countries due to their toxicity and environmental impact.
- Alkaline batteries Alkaline batteries and alkaline cells are a type of disposable battery or rechargeable battery dependent upon the reaction between zinc and manganese dioxide (Zn/Mn are made in the same button sizes as other types, but typically provide less capacity and less stable voltage (it drops gradually in use) than more costly silver oxide or lithium cells. They are often sold as cheap watch batteries to, and sometimes by, people who do not know the difference[1].
- Zinc-air batteries Zinc-air batteries , and zinc-air fuel cells, (mechanically-rechargeable) are electro-chemical batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexpensive to produce. They are used in hearing aids and in film cameras that previously used mercury batteries use air as the depolarizer A depolarizer or depolariser is a substance used in an electrochemical cell, which takes up electrons during discharging the cell; therefore, it is always an oxidizing agent. The term "depolarizer" can be considered as outdated or misleading since it is based on the concept of "polarization" which is hardly realistic in many and have much higher capacity than other types (they use air from the atmosphere which does not need to be supplied in the battery). A seal is removed before use to allow air to enter the cell; the cell will then self-discharge in a few weeks even if not used up.
For comparison, a cell of diameter 11.6 mm and height 5.4 mm from one reputable manufacturer has the following properties[2]. In many cases there are several batteries of the same chemistry and size with different capacities and properties; figures listed are merely indicative.
- Silver: capacity 200 mAh An ampere-hour or amp-hour is a unit of electric charge, with sub-units milliampere-hour (mAh) and milliampere second (mAs). One ampere-hour is equal to 3,600 coulombs (ampere-seconds), the electric charge transferred by a steady current of one ampere for one hour. The ampere-hour is frequently used in measurements of electrochemical systems such to an end-point of 0.9 V, internal resistance 5–15 ohms, weight 2.3 g
- Alkaline (manganese dioxide): 150 mAh (0.9), 3-9 ohms, 2.4 g
- Mercury 200mAh, 2.6 g
- Zinc-air 620 mAh, 1.9 g
The situation is more complex than these typical figures indicate. Examining datasheets for a manufacturer's range[2] may find a high-capacity alkaline cell with a capacity as high as one of the lower-capacity silver types; or a particular silver cell with twice the capacity of some particular alkaline cell. And if powering equipment requiring a relatively high voltage (e.g., 1.3V) to operate correctly, a silver cell with a flat discharge characteristic will give much longer service than an alkaline cell—even if it has the same specified capacity in mAh to an end-point of 0.9V. If some device seems to "eat up" batteries after the original supplied by the manufacturer is replaced, it may be useful to check the device's requirements and the replacement battery's characteristics. For digital callipers A caliper is a device used to measure the distance between two opposing sides of an object. A caliper can be as simple as a compass with inward or outward-facing points. The tips of the caliper are adjusted to fit across the points to be measured, the caliper is then removed and the distance read by measuring between the tips with a measuring tool,, in particular, some are specified to require at least 1.25V to operate; some are reported to malfunction when the voltage drops to 1.38V[3][4].
Datasheets A datasheet, data sheet, or spec sheet is a document summarizing the performance and other technical characteristics of a product, machine, component , material, a subsystem (e.g. a power supply) or software in sufficient detail to be used by a design engineer to integrate the component into a system. Typically, a datasheet is created by the for some cheaper cells, particularly alkaline, are not available, so it is not possible to say whether capacities are about the same as for documented types[5]. Discussions on web forums suggest that they can be very poor[6].
In some ways the size is the most important property of a button cell: cells of different chemistry are to a considerable extent interchangeable. In practice only cells of fairly similar voltages are made in any given size; there is no "CR1154" 3V lithium battery mechanically interchangeable with a 1.5V silver or alkaline size 1154 cell. Use of a battery of significantly higher voltage than equipment is designed for can cause permanent damage, but use of a cell of the right voltage but unsuitable characteristics can only lead to short battery life or failure to operate equipment.
Type designation
See also: Battery nomenclatureInternational standard International standards are standards developed by international standards organizations. International standards are available for consideration and use, worldwide. The most prominent organisation is the International Organization for Standardization IEC The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology". IEC standards cover a vast range of technologies from power 60086-3 defines an alphanumeric coding system for "Watch batteries". Manufacturers often have their own naming system; for example, the cell called LR1154 by IEC standard is named AG13, LR44, 357, A76, and other names by different manufacturers. The IEC standard and some others encode the case size so that the numeric part of the code is uniquely determined by the case size; other codes do not encode size directly.
Examples of batteries conforming to the IEC standard are CR2032, SR516, and LR1154, where the letters and numbers indicate the following characteristics.
Electrochemical system
The first letter identifies the chemical composition of the battery, which also implies a nominal voltage:
Notes:
- for types with stable voltage falling precipitously at end-of-life (cliff-top voltage-versus-time graph), the end-voltage is the value at the "cliff-edge", after which it drops extremely rapidly. For types which lose voltage gradually (slope graph, no cliff-edge) the end-point is the voltage beyond which it is deemed that equipment will not work properly, typically 1.0 or 0.9V.
- Common names are conventional rather than uniquely descriptive; for example, a cell called a "silver [oxide] cell" rather than "alkaline" actually has an alkaline electrolyte.
"L", "S", and "C" type cells are today the most commonly-used types in quartz watches A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks are at least an order of magnitude more accurate than good mechanical clocks. Generally, some form of digital logic counts the cycles of this, calculators A calculator is a small , usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators, small PDA The term PDA was first used on January 7, 1992, by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, Nevada, referring to the Apple Newton. In 1996, Nokia introduced the first mobile phone with full PDA functionality, the 9000 Communicator, which has since grown to become the world's best-selling PDA and which spawned devices, computer clocks, and blinky lights. Miniature zinc-air batteries Zinc-air batteries , and zinc-air fuel cells, (mechanically-rechargeable) are electro-chemical batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexpensive to produce. They are used in hearing aids and in film cameras that previously used mercury batteries are used in hearing aids A hearing aid is an electroacoustic device which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sound for the wearer. Earlier devices, known as an "ear trumpet" or "ear horn", were passive funnel-like amplification cones designed to gather sound energy and direct it into the ear canal and medical instruments.
LR = Alkaline, at 1.5V
SR = Silver Oxide, at 1.55V (higher capacity and more stable voltage than alkaline)
CR = Lithium/manganese dioxide, at 3V
BR = Lithium carbon monofluoride, 3 V, (low drain/long life/high temperature uses)
Package size
4.5-Volt, D, C, AA, AAA, 9-Volt, SR41/AG3, SR44/AG13 cellsPackage size of button batteries using standard names is indicated by a two digit code representing a standard case size, or a 3 or 4 digit code representing the cell diameter and height. The first 1 or 2 digits encode the outer diameter of the battery in whole millimeters, rounded down; exact diameters are specified by the standard, and there is no ambiguity, e.g., any cell with an initial "9" is 9.5 mm in diameter, no other value between 9.0 and 9.9 is used. The last 2 digits are the overall height in tenths of a millimeter.
| Number code | Nominal diameter | Tolerance |
|---|---|---|
| 4 | 4.8 | ±0.15 mm |
| 5 | 5.8 | ±0.15 mm |
| 6 | 6.8 | ±0.15 mm |
| 7 | 7.9 | ±0.15 mm |
| 9 | 9.5 | ±0.15 mm |
| 10 | 10.0 | ±0.20 mm |
| 11 | 11.6 | ±0.20 mm |
| 12 | 12.5 | ±0.25 mm |
| 16 | 16 | ±0.25 mm |
| 20 | 20 | ±0.25 mm |
| 23 | 23 | ±0.50 mm |
| 24 | 24.5 | ±0.50mm |
Examples:
- CR2032: lithium, 20 mm diameter, 3.2 mm height
- SR516: silver, 5.8 mm diameter, 1.6 mm height
- LR1154/SR1154: alkaline/silver, 11.6 mm diameter, 5.4 mm height. The two-digit codes LR44/SR44 are often used for this size
Letter suffix
After the package code, the following additional letters may optionally appear in the type designation to indicate the electrolyte used:
- P: potassium hydroxide Potassium hydroxide can be found in pure form by reacting sodium hydroxide with impure potassium. Potassium hydroxide is usually sold as translucent pellets, which will become tacky in air because KOH is hygroscopic. Consequently, KOH typically contains varying amounts of water . Its dissolution in water is strongly exothermic, meaning the process electrolyte
- S: sodium hydroxide Sodium hydroxide , also known as lye and caustic soda, is a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Worldwide production in 1998 was around 45 million tonnes.[citation needed] Sodium hydroxide electrolyte
- no letter: organic electrolyte
Also:
- W; the battery complies with all the requirements of the international IEC 60086-3 [7] standard for watch batteries.
Other package markings
Apart from the type code described in the preceding section, watch batteries should also be marked with
- the name or trademark of the manufacturer or supplier;
- the polarity (+);
- the date of manufacturing.
The manufacturing date can be abbreviated to the last digit of the year, followed by a digit or letter indicating the month, where O, Y, and Z are used for October, November and December, respectively (e.g., 01 = January 1990 or January 2000, 9Y = November 1999).
Common manufacturer code
A code used by some manufacturers is AG (alkaline) or SG (silver) followed by a number, where 1 equates to standard 621, 2 to 726, 3 to 736, 4 to 626, 5 to 754, 6 to 920 or 921, 7 to 926 or 927, 8 to 1120 or 1121, 9 to 936, 10 to 1130 or 1131, 11 to 721, 12 to 1142, and 13 to 1154. To those familiar with the chemical symbol Chemical symbols may also be modified by the use of superscripts or subscripts to show a specific isotope of an atom. Additionally superscripts may be used to indicate the ionization or oxidation state of an element for silver, "Ag", this may suggest incorrectly that AG cells are silver.
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