A button cell is in electrical engineering an electrochemical cell having a round cross-section, whose total height is less than the overall diameter and the cell voltages from 1.35 to 3.6 volt outputs. It got its name from the design, which is similar in size and shape to a button . Similarly, they are called button cells or particularly flat specimens in English, coin cells ("coin" = coin). Depending on the electrode material, a distinction is made between a. Silver oxide , mercury oxide or lithium cells .
Colloquially, the term battery is sometimes incorrectly used for button cell , but it refers to the interconnection of several electrochemical cells.
Button cells are used as a voltage source in devices that have a low power requirement or that are rarely used. Examples are pocket calculators , wristwatches , hearing aids , mini-flashlights or the buffering of static SRAM components on mainboards in computers .
The first button cells were mercury oxide-zinc cells and were introduced by Samuel Ruben for the US military in 1942 .
Areas of application / distinction
For different requirements, there are different types of batteries, which differ from the voltage curve to the durability and should also be used accordingly. For wristwatches, it is usually silver oxide batteries, for all-round applications, such as. B. for small LED flashlights or children's toys, cheaper alkaline batteries.
Lithium button cells are used wherever a power supply is required for a long time, e.g. B. Type CR2032 in computers on motherboards to act as a backup battery to ensure the voltage supply for the clock and the CMOS RAM when the computer is disconnected from the mains or switched off. Also, CR2016, CR2025, etc. are commonly used lithium button cells that are found in smaller electronic devices and many car keys . In a few cases there are also wristwatches with lithium batteries, which are then noticeably large (example CR2320).
Alkaline-manganese button cells are very inexpensive and are therefore often used in small electronic devices such as e.g. B. pocket calculators, and also used in flashlights with LED technology. Since these batteries can leak, they should never be used as a replacement in a watch. Names like L1154, LR44, V13GA, AG13, KA76, LR44H and GPA76 all refer to the same type of battery.
Silver oxide button cells with designations such as SR1154, SR44, SR44SW or 303 are in most cases used in wristwatches. A distinguishing feature within these types is the current-carrying capacity:
* Low-Drain : Lower current-carrying capacity, e.g. B. for watches with high leakage security ( electrolyte , caustic soda).
* High drain : higher current carrying capacity, e.g. B. for photo and remote control applications, with good leakage protection (electrolyte potassium hydroxide).
Zinc-air button cells are primarily used as hearing aid batteries .
In addition to the mercury-zinc button cells (30% Hg) that were no longer manufactured , silver oxide cells (1% Hg) and zinc-air button cells (2% Hg) also contained mercury. Since autumn 2015, the use of mercury has also been banned within the EU.
Identical dimensions do not mean that they are the same type of battery. Some suppliers use a wide variety of designations for a product, the dimensions being identical, but different battery types (silver oxide 1.55 V, alkaline 1.5 V, zinc-air 1.4 V) such as SR41, AG3, SG3 , LR41, PR41, 192, 384, 392. Such listings list silver oxide watch batteries, alkaline button cells and zinc-air hearing aid batteries as supposedly compatible.
The self-discharge rate of a battery depends on the electrode material and is very different; In addition to design and capacity, it is one of the selection criteria for the respective application: The battery in a clock or a digital clinical thermometer should last as many years as possible and therefore have a low self-discharge. As a rule, silver oxide cells can also be used instead of alkaline manganese cells. So compatibility and price are rarely the only criteria when choosing a battery.
Explanations for the table:
- "Type IEC 1" column: size designations according to method 1 of the IEC-60086 standard. There was still no connection between type number and cell size. Standard sizes were simply specified or included in the standard and numbered consecutively.
- Column " ø " and "height": total diameter and total height in millimeters.
- Column "N./max": For some types are the millimeter indications as N ennwert in the standard set (nominal cell dimensions) , for most as Max imalwert ( Maximum battery dimensions ).
- Column "Type IEC 2": IEC size designations according to method 2 (from October 1990) - This column was added here separately. The designations result from the maximum values for diameter and height. Since for some types only the nominal values are mentioned in the standard, it may not be possible to infer the IEC-2 designations directly, which is why these only appear in italics.
- "Shape" column: All round cells whose height is smaller than their diameter are considered button cells and are highlighted in orange .
|R06||10.0 mm||22.0 mm||N.||R10220||H ≥ ø|
|R03||10.5 mm||44.5 mm||Max.||R10445||H ≥ ø , AAA, Micro|
|R01||12.0 mm||14.7 mm||Max.||R12147||H ≥ ø|
|R0||11.0 mm||19.0 mm||N.||R11190||H ≥ ø|
|R1||12.0 mm||30.2 mm||Max.||R12302||H ≥ ø , N, Lady|
|R3||13.5 mm||25.0 mm||N.||R13250||H ≥ ø|
|R4||13.5 mm||38.0 mm||N.||R13380||H ≥ ø|
|R6||14.5 mm||50.5 mm||Max.||R14505||H ≥ ø , AA, Mignon|
|R9||16.0 mm||6.2 mm||Max.||R1662||H < ø , button cell|
|R10||21.8 mm||37.3 mm||Max.||R21373||H ≥ ø|
|R12||21.5 mm||60.0 mm||Max.||R21600||H ≥ ø|
|R14||26.2 mm||50.0 mm||Max.||R26500||H ≥ ø , C, baby|
|R15||24.0 mm||70.0 mm||N.||R24700||H ≥ ø|
|R17||25.5 mm||17.0 mm||N.||R25170||H < ø , button cell|
|R18||25.5 mm||83.0 mm||N.||R25830||H ≥ ø|
|R19||32.0 mm||17.0 mm||N.||R32170||H < ø , button cell|
|R20||34.2 mm||61.5 mm||Max.||R34615||H ≥ ø , D, mono|
|R22||32.0 mm||75.0 mm||N.||R32750||H ≥ ø|
|R25||32.0 mm||91.0 mm||N.||R32910||H ≥ ø|
|R26||32.0 mm||105.0 mm||N.||R32 / 105||H ≥ ø|
|R27||32.0 mm||150.0 mm||N.||R32 / 150||H ≥ ø|
|R40||67.0 mm||172.0 mm||Max.||R67 / 172||H ≥ ø|
|R41||7.9 mm||3.6 mm||Max.||R736||H < ø , button cell|
|R42||11.6 mm||3.6 mm||Max.||R1136||H < ø , button cell|
|R43||11.6 mm||4.2 mm||Max.||R1142||H < ø , button cell|
|R44||11.6 mm||5.4 mm||Max.||R1154||H < ø , button cell|
|R45||9.5 mm||3.6 mm||N.||R936||H < ø , button cell|
|R48||7.9 mm||5.4 mm||Max.||R754||H < ø , button cell|
|R50||16.4 mm||16.8 mm||Max.||R16168||H ≥ ø|
|R51||16.5 mm||50.0 mm||N.||R16500||H ≥ ø|
|R52||16.4 mm||11.4 mm||Max.||R16114||H < ø , button cell|
|R53||23.2 mm||6.1 mm||Max.||R2361||H < ø , button cell|
|R54||11.6 mm||3.1 mm||Max.||R1130||H < ø , button cell|
|R55||11.6 mm||2.1 mm||Max.||R1121||H < ø , button cell|
|R56||11.6 mm||2.6 mm||Max.||R1126||H < ø , button cell|
|R57||9.5 mm||2.7 mm||Max.||R927||H < ø , button cell|
|R58||7.9 mm||2.1 mm||Max.||R721||H < ø , button cell|
|R59||7.9 mm||2.6 mm||Max.||R726||H < ø , button cell|
|R60||6.8 mm||2.2 mm||Max.||R621||H < ø , button cell|
|R61||7.8 mm||39.0 mm||N.||R7390||H ≥ ø|
|R62||5.8 mm||1.7 mm||Max.||R516||H < ø , button cell|
|R63||5.8 mm||2.2 mm||Max.||R521||H < ø , button cell|
|R64||5.8 mm||2.7 mm||Max.||R527||H < ø , button cell|
|R65||6.8 mm||1.7 mm||Max.||R616||H < ø , button cell|
|R66||6.8 mm||2.6 mm||Max.||R626||H < ø , button cell|
|R67||7.9 mm||1.7 mm||Max.||R716||H < ø , button cell|
|R68||9.5 mm||1.7 mm||Max.||R916||H < ø , button cell|
|R69||9.5 mm||2.1 mm||Max.||R921||H < ø , button cell|
|R70||5.8 mm||3.0 mm||Max.||R530||H < ø , button cell|
The voltage of a button cell depends on its chemical composition.
|Cell type||1st letter of the
|nominal voltage||Examples b|
|Mercury Oxide Zinc Cell a||M.||1.35V||MR52|
|Zinc-air cell||P||1.4 V
(or 1.45 V)
|Alkaline manganese cell||L.||1.5V||LR44
|Nickel oxyhydroxide cell||Z||1.5 V
(or 1.65 V)
|Silver oxide zinc cell||S.||1.55V||SR44
|Lithium manganese dioxide cell||C.||3.0V||CR2016
|Lithium carbon monofluoride cell||B.||3.0V||BR2016|
The smaller a button cell, the lower the amount of charge contained in the cells , which is expressed in milliampere hours (mAh) . Despite the very small capacities, button cells, especially in wristwatches and pocket calculators with liquid crystal displays (LCD), can have a service life that can be measured in years.
Because of the discharge through leakage currents, contamination (e.g. traces of grease from fingers) should be avoided.
Silver oxide cells usually have a higher nominal capacity than alkaline manganese cells.
Structure of the model numbers
Lithium button cells
C R1620 = lithium battery with 16 mm diameter and 2.0 mm height. The "C R " stands for a lithium battery as R undzelle, then the diameter follows in mm, the last digits indicate the thickness in 1 / 10 mm to. Manufacturer's own names have hardly spread for lithium button cells.
Alkaline button cells
L R1154 = Alkaline battery with a diameter of 11.6 mm and a height of 5.4 mm. The "L R " stands for an alkaline battery as R undzelle, then the diameter follows in mm (rounded), the last digits indicate the thickness in 1 / 10 mm to. A wide variety of names are repeatedly used for these button cells and sometimes mixed with one another. There is even packaging on which the designations SR44, LR44, 357 and L1154 are mentioned in one line. So it is z. B. an alkaline and a silver oxide battery. The batteries have the same dimensions.
Silver oxide button cells
S R626 = silver oxide battery with 6 mm diameter and 2.6 mm height. The " SR " stands for an S ilberoxid battery as R undzelle, then the diameter follows in mm (rounded). The last digits indicate the thickness in 1 ⁄ 10 mm. These batteries are mainly used in wristwatches. The advantage of silver oxide batteries is that the voltage remains the same for a long time. In principle, silver oxide batteries are only produced as button cells.
Zinc-air button cells
Zinc-air batteries have a very high energy density. They are externally recognizable by the mostly colored sealing sticker, which keeps the air required for the chemical process away from the battery until it is activated. The almost horizontal discharge curve, which only drops steeply towards the end of the capacity, and the comparatively high current output should be emphasized. These cells are mainly used as hearing aid batteries .
Mercury button cells
M R9 is a mercury button cell with a diameter of 16 mm and a height of 6.2 mm. In the past, these batteries were mainly used in cameras . The advantage of the mercury button cell is that, in addition to more than twice the energy density compared to alkaline button cells, it offers an almost constant voltage of 1.35 V over a wide discharge range. In the first cameras with electronic circuits, for example for exposure measurement, the circuit complexity was lower because there was no additional voltage stabilization required.
In the mercury button cell, the poisonous and eponymous mercury oxide is used on the positive cathode . As a result, mercury button cells are no longer allowed to be placed on the market in the EU under the RoHS guidelines . Similar rules also apply in other regions. When switching to button cells based on zinc-air, alkali-manganese or silver oxide, it is necessary to check in each individual case whether they are suitable due to the different voltages and different discharge properties.
Overview of size and battery types of button cells
The names of various button cells are specified in the European standard EN 60086 . However, there are still popular names from the respective manufacturers.
Explanation of the comparison table:
- Columns “Diameter” and “Height”: Most button cells are only manufactured with an accuracy of tenths, not hundredths of a millimeter. This is absolutely standard-compliant, as only maximum values are coded in the IEC designation. An SR11 30 must not be higher than a rounded 3.0 millimeters. According to the technical drawing, the manufacturer Renata produces this type with a nominal height of "3.05 mm + 0 / -0.25 mm". On its website, however, the manufacturer states a height of "3.1 mm". Since this contradicts the IEC designation, such information is only given in brackets in the table. At Varta, a fluctuation range of up to 0.4 mm is indicated for some models, for example the V 303 MF (SR1154) : diameter from 11.25 to 11.60 mm, height from 5.0 to 5.4 mm.
- "Current carrying capacity" column: (see also the section on areas of application / distinction ) In the IEC designations, the combination of both electrode materials is coded, but not the type of electrolyte. For a producer, on the other hand, it is crucial whether, for example, a potash or a caustic soda is used in a cell. Accordingly, there are two manufacturer names for some IEC types - especially those with silver oxide (SR) - one for the low-drain and one for the high-drain version.
- LD = low drain, lower current carrying capacity, NaOH electrolyte (caustic soda)
- HD = high drain, higher current carrying capacity, KOH electrolyte (potassium hydroxide)
- Column IEC 60086: The first letter of the type designation codes the type of internal structure of the battery (see section Voltage ). The second codes the design - for button cells there is always an R for "round", ie cylindrical shape. The numbers behind the letters are responsible for the size of the batteries. The revision of the IEC-60086 standard resulted in extensive changes:
- With the digits of the old type designations (left column) there was no connection between type number and cell size. Standard sizes were specified or included in the standard and simply numbered.
- When revised in October 1990 (right column), the numbers of the type designation result from the maximum values for the (rounded) standard diameter in millimeters and the exact height in tenths of a millimeter. (This definition applies to cells with a diameter and height of less than 100 millimeters.)
- The table also lists type designations that a manufacturer "currently" no longer produces, but which, due to the old widespread use, can still be found on packaging from other manufacturers, for example. For example, Maxell “currently” no longer manufactures the SR48 (IEC) itself; their designation SR754W or SR754WSW is still common.
|Characteristic values||Standard / Norm||Manufacturer|
|IEC 60086||Europe||United States||Asia (mostly Japan, except GP)|
|Current carrying capacity||
|4.8||1.6||1.55||LD||8 - 9||-||SR416||V337MF||337||-||SR416SW|
|5.8||1.2||1.55||LD||5 - 6||-||SR512||V335MF||335||-||622||SR512SW||SB-AB||280-68|
|1.6||1.55||LD||10 - 12||SR62||SR516||V317MF||317||-||616||SR516SW||280-58||GP317|
|2.7||1.55||LD||16-21||SR64||SR527||V319MF||319||-||615||SR527SW||SB-AE / DE||280-60||-|
|1.55||LD||15-20||SR60||SR621||SG1||V364MF||364||D364||602||SR621SW||SB-AG / DG||280-34|
|1.55||LD||23 - 32||SR59||SR726||SG2||V397MF||397||D397||607||SR726SW||SB-AL||280-28||GP397|
|1.55||LD||38||SR41||SR736||SG3||V384MF||384||D384||247||SR41SW||SB-A1 / D1||280-18|
|2.6||1.5||-||34 - 45||LR57||LR926||AG7||195||GP95A|
|2.7||1.55||LD||55||SR57||SR927||SG7||V395MF||395||D395||610||SR927SW||SB-AP / DP||280-48||GP395|
|1.55||HD||40 - 42||SR57||SR927||SG7||V399MF||399||D399||613||SR927W||SB-BP / EP||280-44||GP399|
|1.55||HD||42-55||-||SR1120||SG8||V391MF||391||D391||609||SR1120W||SB-BS / ES||280-30||GP391|
|1.55||HD||42-55||SR55||SR1121||SG8||V391MF||391||D391||609||SR1121W||SB-BS / ES||280-30||GP391|
|2.6||? R56 1||? R1126||-|
Rechargeable button cells
Button cells are also available as rechargeable batteries ( accumulators for short) that are used in computers, laptops, cordless telephones, headphones, hearing aids, etc. The nominal voltage of nickel-cadmium batteries or nickel-metal hydride batteries is 1.2 volts . In Germany, nickel-cadmium button cells are now banned by the Battery Act and have therefore completely disappeared from the market.
In a few cases, rechargeable lithium-ion batteries are also used in watches. Rechargeable button cells are named similarly to non-rechargeable cells. So have z. B. the button cells CR2032 and the rechargeable LIR2032 have the same dimensions. The cell voltage of the rechargeable "LIR" variant is 3.6 volts, which is 20% higher than that of the "CR" disposable variant, so they cannot easily be exchanged for one another.
|MT-516||1.5V||5.8 mm||1.6 mm|
|MT-621||1.5V||6.8 mm||2.1 mm|
|MT-920||1.5V||9.5 mm||2.0 mm|
Button cells and toddlers
Like all small parts, button cells should be kept safe from children. Tissue damage can occur if the patient remains in the esophagus or stomach for a long time, which rarely occurs. “If button cells are swallowed, the button cells can get stuck in the esophagus and seriously damage the mucous membrane. The "Assessment of Poisoning" commission of the Federal Institute for Risk Assessment (BfR) therefore advises particular caution. "
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