HOME

TheInfoList



OR:

A button cell, watch battery, or coin battery is a small single-cell battery shaped as a squat cylinder typically in diameter and high — resembling a
button A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole. In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood, ...
. Stainless steel usually forms the bottom body and positive
terminal Terminal may refer to: Computing Hardware * Terminal (electronics), a device for joining electrical circuits together * Terminal (telecommunication), a device communicating over a line * Computer terminal, a set of primary input and output devi ...
of the cell; insulated from it, the metallic top cap forms the negative terminal. Button cells are used to power small portable electronics devices such as wrist watches and
pocket calculator An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-size ...
s. Wider variants are usually called coin cells. Devices using button cells are usually designed around 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, holding their charge for a long time if not used. Relatively high-power devices such as hearing aids may use a
zinc–air battery Zinc–air batteries (non-rechargeable), and zinc–air fuel cells (mechanically rechargeable) are metal–air batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexp ...
, which has a much higher capacity for a given size, but dries out after a few weeks even if not used. Button cells are single cells, usually disposable
primary cell A primary battery or primary cell is a battery (a galvanic cell) that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (rechargeable battery). In general, the electrochemical reaction ...
s. Common
anode An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic ...
materials are zinc or lithium. Common
cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in whi ...
materials are manganese dioxide,
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. Preparation Silver oxide can be prepared by combining aqueous solutions of silver nitrate and a ...
,
carbon monofluoride Carbon monofluoride (CF, CFx, or (CF)n), also called polycarbon monofluoride (PMF), polycarbon fluoride, poly(carbon monofluoride), and graphite fluoride, is a material formed by high-temperature reaction of fluorine gas with graphite, charcoal, ...
,
cupric oxide Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or copper(I) oxide (cuprous oxide). As a mineral, it is known as tenorite. It is ...
or oxygen from the air.
Mercuric oxide Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula Hg O. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is ...
button cells were formerly common, but are no longer available due to the toxicity and environmental effects of mercury. Button cells are dangerous for small children, as when swallowed they can cause severe internal burns and significant injury or death.
Duracell Duracell Inc. is an American manufacturer of alkaline batteries, specialty cells, rechargeables and smart power systems, owned by Berkshire Hathaway. The company has its origins in the 1920s, through the work of Samuel Ruben and Philip Mallory ...
has attempted to mitigate this by adding a bitter coating to their batteries.


Properties of cell chemistries

Cells of different chemical composition made in the same size are mechanically interchangeable. However, the composition can affect service life and voltage stability. Using the wrong cell may lead to short life or improper operation (for example, light metering on a camera requires a stable voltage, thus silver cells are usually specified). Sometimes different cells of the same type, size and capacity are optimized for different loads by using different electrolytes, so that one may have longer service life than the other when supplying a relatively high current. Alkaline batteries are made in the same button sizes as the other types, but typically provide less capacity and less stable voltage than more costly silver oxide or lithium cells. Silver cells may have an output voltage that is stable until it suddenly drops at end of life. This varies for individual types; one manufacturer ( Energizer) offers three silver oxide cells of the same size, 357–303, 357-303H and EPX76, with capacities ranging from 150 to 200 
mAh ''Mångha'' (') is the Avestan for "Moon, month", equivalent to Persian ''Māh'' (; Old Persian ). It is the name of the lunar deity in Zoroastrianism. The Iranian word is masculine. Although Mah is not a prominent deity in the Avestan scrip ...
, 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 also supply a stable voltage, but are now banned in many countries due to their toxicity and environmental impact. Zinc-air batteries use air as the depolarizer and have much higher capacity than other types, as they take that air from the atmosphere. Cells have an air-tight seal which must be removed before use; they will then dry out in a few weeks, regardless of use. For comparison, the properties of some cells from one manufacturer with diameter 11.6 mm and height 5.4 mm were listed in 2009 as:Energizer website
, with datasheets for many batteries of several chemistries
*Silver: capacity 200 mAh to an end-point of 0.9 V,
internal resistance A practical electrical power source which is a linear electric circuit may, according to Thévenin's theorem, be represented as an ideal voltage source in series with an impedance. This impedance is termed the internal resistance of the source. ...
5–15 Ω, weight 2.3 g *Alkaline (manganese dioxide): 150 mAh (0.9), 3–9 Ω, 2.4 g *Mercury: 200 mAh, 2.6 g *Zinc-air: 620 mAh, 1.9 g Examining datasheets for a manufacturer's range may show 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 a particular alkaline cell. If the powered equipment requires a relatively high voltage (e.g., 1.3 V) 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 0.9 V. If a 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 calipers, in particular, some are specified to require at least 1.25 V to operate and others 1.38 V.Caliper Battery Life
. Davehylands.com. Retrieved on 2015-11-08.
While alkaline, silver oxide, and mercury batteries of the same size may be mechanically interchangeable in any given device, use of a cell of the right voltage but unsuitable characteristics can lead to short battery life or failure to operate equipment. Common lithium primary cells, with a terminal voltage around 3 volts, are not made in sizes interchangeable with 1.5 volt cells. Use of a battery of significantly higher voltage than equipment is designed for can cause permanent damage.


Type designation

International standard
IEC The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...
60086-3 defines an alphanumeric coding system for "Watch batteries". Manufacturers often have their own naming system; for example, the cell called LR1154 by the 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 in the IEC standard system identifies the chemical composition of the battery, which also implies a nominal voltage: 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 the voltage drops extremely rapidly. For types which lose voltage gradually (slope graph, no cliff-edge), the end-point is the voltage beyond which further discharge will cause damage to either the battery or the device it is powering, typically 1.0 or 0.9 V. Common names are conventional rather than uniquely descriptive; for example, a ''silver (oxide) cell'' has an alkaline electrolyte. ''L'', ''S'', and ''C'' type cells are today the most commonly used types in
quartz watch Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical fo ...
es,
calculator An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-sized ...
s, small
PDA PDA may refer to: Science and technology * Patron-driven acquisition, a mechanism for libraries to purchase books *Personal digital assistant, a mobile device * Photodiode array, a type of detector * Polydiacetylenes, a family of conducting po ...
devices, computer clocks, and blinky lights. Miniature zinc-air batteries – ''P'' type – are used in
hearing aid A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers su ...
s and medical instruments. In the IEC system, larger cells may have no prefix for the chemical system, indicating they are zinc-carbon batteries; such types are not available in button cell format. The second letter, ''R'', indicates a round (cylindrical) form. The standard only describes primary batteries. Rechargeable types made in the same case size will carry a different prefix not given in the IEC standard, for example some ''ML'' and ''LiR'' button cells use rechargeable lithium technology.


Package size

Package size of button batteries using standard names is indicated by a 2-digit code representing a standard case size, or a 3- or 4-digit code representing the cell diameter and height. The first one or two 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 two digits are the overall height in tenths of a millimeter. Examples: *CR2032: lithium, 20 mm diameter, 3.2 mm height, 220 mAh *CR2032H; lithium, 20 mm diameter, 3.2 mm height 240 mAh *CR2025: lithium, 20 mm diameter, 2.5 mm height, 170 mAh *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 Some coin cells, particularly lithium, are made with solder tabs for permanent installation, such as to power memory for configuration information of a device. The complete nomenclature will have prefixes and suffixes to indicate special terminal arrangements. For example, there is a plug-in and a solder-in CR2032, a plug-in and three solder-in BR2330s in addition to CR2330s, and many rechargeables in 2032, 2330, and other sizes.


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 electrolyte *S: sodium hydroxide electrolyte *No letter: organic electrolyte *SW: low drain type for quartz watches (analog or digital) without light, alarm, or chronograph functions *W: high drain type for all quartz watches, calculators and cameras. The battery complies with all the requirements of the international IEC 60086-3 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.


Date codes

Often a 2-letter code (sometimes on the side of the battery) where the first letter identifies the manufacturer and the second is the year of manufacture. For example: * YN – the letter N is the 14th letter in the alphabet – indicates the cell was manufactured in 2014. There is no universal standard. 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 2010 or 2000, 9Y = November 2019 or 2009).


Common manufacturer code

A code used by some manufacturers is ''AG'' (alkaline) or ''SG'' (silver) followed by a number, as follows To those familiar with the
chemical symbol Chemical symbols are the abbreviations used in chemistry for chemical elements, functional groups and chemical compounds. Element symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with t ...
for silver, Ag, this may suggest incorrectly that AG cells are silver.


Rechargeable variants

In addition to disposable (single use) button cells, rechargeable batteries in many of the same sizes are available, with lower capacity than disposable cells. Disposable and rechargeable batteries are manufactured to fit into a holder or with solder tags for permanent connection. In equipment with a battery holder, disposable or rechargeable batteries may be used, if the voltage is compatible. A typical use for a small rechargeable battery (in coin or other format) is to back up the settings of equipment which is normally permanently mains-powered, in the case of power failure. For example, many central heating controllers store operation times and similar information in volatile memory, lost in the case of power failure. It is usual for such systems to include a backup battery, either a disposable in a holder (current drain is extremely low and life is long) or a soldered-in rechargeable. Rechargeable NiCd button cells were often components of the backup battery of older computers; non-rechargeable lithium button cells with a lifetime of several years are used in later equipment. Rechargeable batteries typically have the same dimension-based numeric code with different letters; thus CR2032 is a disposable battery while ML2032, VL2032 and LIR2032 are rechargeables that fit in the same holder if not fitted with solder tags. It is mechanically possible, though hazardous, to fit a disposable battery in a holder intended for a rechargeable; holders are fitted in parts of equipment only accessible by service personnel in such cases.


Health issues


Accidental ingestion

Button cells are attractive to small children; they may put them in their mouth and swallow them. The ingested battery can cause significant damage to internal organs. The battery reacts with bodily fluids, such as mucus or saliva, creating a circuit which can release an alkali that is strong enough to burn through human tissue.Paull, John (2022
Silent Nursery: Button Battery Fatalities in Children – the Long Road from Externality to Obsolescence
International Journal of Clinical and Experimental Medicine Research, 6 (3): 301–308.
Swallowed batteries can cause damage to the lining of the esophagus, and can create a hole in the esophagus lining in two hours. In severe cases, damage can cause a passage between the esophagus and the trachea. Swallowed button cells can damage the vocal cords. They can even burn through the blood vessels in the chest area, including the
aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...
. In the United States, 44 child deaths were reported from button battery ingestion in 2002–2021. In Greater Manchester, England, with a population of 2,700,000, two children between 12 months and six years old died, and five suffered life-changing injuries, in the 18 months leading up to October 2014. In the United States, on average over 3,000 pediatric button batteries ingestions are reported each year with a trend toward major and fatal outcomes increasing. Coin cells of diameter 20 mm or greater cause the most serious injuries, even if expended and intact. In Auckland, New Zealand as of 2018 there are about 20 cases per year requiring hospitalization. In 2020,
Duracell Duracell Inc. is an American manufacturer of alkaline batteries, specialty cells, rechargeables and smart power systems, owned by Berkshire Hathaway. The company has its origins in the 1920s, through the work of Samuel Ruben and Philip Mallory ...
announced that they were coating some of their lithium button cells with a
bitterant A bitterant (or bittering agent) is a chemical that is added to a product to make it smell or taste bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances. Examples of use *The add ...
compound to discourage children from ingesting them. An alternative solution is to design (or litigate) the offending cells, mostly 20mm lithium cells, out of the supply chain.Paull, John (2021)
Button batteries and child deaths: Market failure of unsafe products
International Journal of Clinical and Experimental Medicine Research, 2021, 5(3), 297–303
Children most at risk of button battery ingestion are those aged 5 years and under. Three child deaths in Australia reveal that in each case: i) the ingestion was not witnessed, ii) the source of the battery remains unknown, iii) initial
misdiagnosis A medical error is a preventable adverse effect of care ("iatrogenesis"), whether or not it is evident or harmful to the patient. This might include an inaccurate or incomplete diagnosis or treatment of a disease, injury, syndrome, behavior, i ...
delayed appropriate intervention, iv) diagnosis was confirmed by X-ray, v) in each case the battery lodged in the child's oesophagus, vi) the offending batteries were 20mm lithium cells, vii) death occurred 19 days to 3 weeks after ingestion. The presenting symptoms of button cell ingestion may be misdiagnosed and attributed to common non life-threatening childhood maladies.


Mercury and cadmium

Some button cells contain mercury or
cadmium Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...
, which are toxic. In early 2013 the European Parliament Environment Committee voted for a ban on the export and import of a range of mercury-containing products such as button cells and other batteries, to be imposed from 2020.148 Kb"Directive 2013/56/EU amending Directive 2006/66/EC"
, European Parliament & Council, 20 November 2013, Retrieved 7 April 2015


See also

*
List of battery sizes This is a list of the sizes, shapes, and general characteristics of some common primary and secondary battery types in household, automotive and light industrial use. The complete nomenclature for a battery specifies size, chemistry, termina ...
* List of battery types *
Battery recycling Battery recycling is a recycling activity that aims to reduce the number of batteries being disposed as municipal solid waste. Batteries contain a number of heavy metals and toxic chemicals and disposing of them by the same process as regular ...
*
Artificial cardiac pacemaker An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart eit ...
* Implantable cardioverter-defibrillator


References


Sources

* IEC 60086-3: Primary batteries – Part 3: Watch batteries. International Electrotechnical Commission, Geneva, 1995. (also: BS EN 60086-3:1996) * Sample of data sheets available fro
Energizer
:   *  


External links


Watch battery cross reference table
* (includes discharge characteristics) *  6 September 2006 (re recycling and disposal of batteries) {{Portal bar, Energy, Electronics Battery shapes