An ampere-hour or amp-hour (symbol: A⋅h or A h; often simplified as Ah) is a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3,600 coulombs.[1][2]
A milliampere second (mA⋅s) is a unit of measurement used in X-ray imaging, diagnostic imaging, and radiation therapy. It is equivalent to a millicoulomb. This quantity is proportional to the total X-ray energy produced by a given X-ray tube operated at a particular voltage.[3] The same total dose can be delivered in different time periods depending on the X-ray tube current.
To help express energy, computation over charge values in ampere-hour requires precise data of voltage: in a battery system, for example, accurate calculation of the energy delivered requires integration of the power delivered (product of instantaneous voltage and instantaneous current) over the discharge interval.[4] Generally, the battery voltage varies during discharge; an average value or nominal value may be used to approximate the integration of power.[5]
When comparing the energy capacities of battery-based products that might have different internal cell chemistries or cell configurations, a simple ampere-hour rating is often insufficient. For example, at 3.2 V for a LiFePO4 battery cell, the perceived energy capacity of a small UPS product that has multiple DC outputs at different voltages but is simply listed with a single ampere-hour rating, e.g., 8800 mAh, would be exaggerated by a factor of 3.75 compared to that of a sealed 12-volt lead-acid battery where the ampere-hour rating, e.g., 7 Ah, is based on the total output voltage rather than the internal cell voltage, so the 12-volt output of the example UPS product can actually deliver only about a third of the energy of the example battery, not a quarter more energy. But a direct replacement product for the example battery, in the same form factor and comparable output voltage and energy capacity but based on LiFePO 4, might also be specified as 7 Ah, here based on output voltage rather than cell chemistry. For consumers without an engineering background, these difficulties would be avoided by a specification of the watt-hour rating instead (or additionally).[citation needed]
In other units of electric chargeedit
One ampere-hour is equal to (up to 4 significant figures):
An AA sizedry cell has a capacity of about 2,000 to 3,000 milliampere-hours.
An average smartphone battery usually has between 2,500 and 4,000 milliampere-hours of electric capacity.
Automotive car batteries vary in capacity but a large automobile propelled by an internal combustion engine would have about a 50-ampere-hour battery capacity.
Since one ampere-hour can produce 0.336 grams of aluminium from molten aluminium chloride, producing a ton of aluminium required transfer of at least 2.98 million ampere-hours.[6]
^"electric charge (Symbol Q). IEV 113-02-10". electropedia.org. International Electrotechnical Commission (IEC). 2020. Retrieved 2020-09-20. Note 7 to entry: The coherent SI unit of electric charge is coulomb, C. The unit ampere-hour is used for electrolytic devices, such as storage batteries: 1 A·h = 3,6 kC.
^Thompson, Ambler; Taylor, Barry N. (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811(PDF) (2nd ed.). Gaithersburg: National Institute of Standards and Technology. p. 45. To convert from ampere hour (A·h) ... to coulomb (C) ... Multiply by 3.6 E+03
^X-ray Safety Handbook, 9.0 Terms and Definitions, VirginiaTech Environmental, Health and Safety Services July 23, 2007, at the Wayback Machine
^Efty Abir, Najrul Islam (2016). "How to Calculate Amp Hours – Learn of Convert Watts to Amps". Leo Evans. Retrieved 8 December 2016.
^National Research Council (U.S.) (2004). Meeting the energy needs of future warriors. National Academies Press. p. 27. ISBN0-309-09261-2.
^T. L. Brown, H. E. Lemay Jr, "Chemistry the Central Science", Prentice-Hall, 1977 ISBN0-13-128769-9 page 562
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ampere, hour, ampere, hour, hour, symbol, often, simplified, unit, electric, charge, having, dimensions, electric, current, multiplied, time, equal, charge, transferred, steady, current, ampere, flowing, hour, coulombs, ampere, hourrechargeable, batteriestop, . An ampere hour or amp hour symbol A h or A h often simplified as Ah is a unit of electric charge having dimensions of electric current multiplied by time equal to the charge transferred by a steady current of one ampere flowing for one hour or 3 600 coulombs 1 2 ampere hourRechargeable batteriesTop AA battery 2500 mA h Bottom AAA battery 1000 mA h General informationUnit systemNon SI metric unitUnit ofElectric chargeSymbolA h A hConversions1 A h in is equal to SI units 3600 C The commonly seen milliampere hour symbol mA h mA h often simplified as mAh is one thousandth of an ampere hour 3 6 coulombs Contents 1 Use 2 In other units of electric charge 3 Examples 4 See also 5 ReferencesUse editThe ampere hour is frequently used in measurements of electrochemical systems such as electroplating and for battery capacity where the commonly known nominal voltage is dropped A milliampere second mA s is a unit of measurement used in X ray imaging diagnostic imaging and radiation therapy It is equivalent to a millicoulomb This quantity is proportional to the total X ray energy produced by a given X ray tube operated at a particular voltage 3 The same total dose can be delivered in different time periods depending on the X ray tube current To help express energy computation over charge values in ampere hour requires precise data of voltage in a battery system for example accurate calculation of the energy delivered requires integration of the power delivered product of instantaneous voltage and instantaneous current over the discharge interval 4 Generally the battery voltage varies during discharge an average value or nominal value may be used to approximate the integration of power 5 When comparing the energy capacities of battery based products that might have different internal cell chemistries or cell configurations a simple ampere hour rating is often insufficient For example at 3 2 V for a LiFePO4 battery cell the perceived energy capacity of a small UPS product that has multiple DC outputs at different voltages but is simply listed with a single ampere hour rating e g 8800 mAh would be exaggerated by a factor of 3 75 compared to that of a sealed 12 volt lead acid battery where the ampere hour rating e g 7 Ah is based on the total output voltage rather than the internal cell voltage so the 12 volt output of the example UPS product can actually deliver only about a third of the energy of the example battery not a quarter more energy But a direct replacement product for the example battery in the same form factor and comparable output voltage and energy capacity but based on LiFePO4 might also be specified as 7 Ah here based on output voltage rather than cell chemistry For consumers without an engineering background these difficulties would be avoided by a specification of the watt hour rating instead or additionally citation needed In other units of electric charge editOne ampere hour is equal to up to 4 significant figures 3 600 coulombs 2 247 1022 elementary charges 0 03731 faradays 1 079 1013 statcoulombs CGS ESU equivalent 360 abcoulombs CGS EMU equivalent Examples editAn AA size dry cell has a capacity of about 2 000 to 3 000 milliampere hours An average smartphone battery usually has between 2 500 and 4 000 milliampere hours of electric capacity Automotive car batteries vary in capacity but a large automobile propelled by an internal combustion engine would have about a 50 ampere hour battery capacity Since one ampere hour can produce 0 336 grams of aluminium from molten aluminium chloride producing a ton of aluminium required transfer of at least 2 98 million ampere hours 6 See also editElectrochemical equivalent Kilowatt hour kW h References edit electric charge Symbol Q IEV 113 02 10 electropedia org International Electrotechnical Commission IEC 2020 Retrieved 2020 09 20 Note 7 to entry The coherent SI unit of electric charge is coulomb C The unit ampere hour is used for electrolytic devices such as storage batteries 1 A h 3 6 kC Thompson Ambler Taylor Barry N 2008 Guide for the Use of the International System of Units SI NIST Special Publication 811 PDF 2nd ed Gaithersburg National Institute of Standards and Technology p 45 To convert from ampere hour A h to coulomb C Multiply by 3 6 E 03 X ray Safety Handbook 9 0 Terms and Definitions VirginiaTech Environmental Health and Safety Services Archived July 23 2007 at the Wayback Machine Efty Abir Najrul Islam 2016 How to Calculate Amp Hours Learn of Convert Watts to Amps Leo Evans Retrieved 8 December 2016 National Research Council U S 2004 Meeting the energy needs of future warriors National Academies Press p 27 ISBN 0 309 09261 2 T L Brown H E Lemay Jr Chemistry the Central Science Prentice Hall 1977 ISBN 0 13 128769 9 page 562 nbsp This standards or measurement related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Ampere hour amp oldid 1198143006, wikipedia, wiki, book, books, 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