# Ampere hour

__: Unit of electric charge__

**Short description**ampere hour | |
---|---|

Rechargeable batteries Top: AA battery (2500 mA⋅h)Bottom: AAA battery (1000 mA⋅h) | |

General information | |

Unit system | Non-SI metric unit |

Unit of | Electric charge |

Symbol | A⋅h |

Conversions | |

1 A⋅h in ... | ... is equal to ... |

SI units | 3600 C |

Electrostatic units | 1.079253×10^{13} statC |

Electromagnetic units | 360 abC |

Gaussian units | 1.079253×10^{13} Fr |

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]}

The commonly seen **milliampere hour** (symbol: **mA⋅h**, **mA h**, simplified as **mAh**) is one-thousandth of an ampere hour (3.6 coulombs).

## Use

The 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]}

## Other measures of electric charge

The Faraday constant is the charge on one mole of electrons, approximately equal to 26.8 ampere hours. It is also used in electrochemical calculations.

## Examples

- An 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

## References

- ↑ "electric charge (Symbol Q). IEV 113-02-10". International Electrotechnical Commission (IEC). 2020. http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=113-02-10. "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*(2nd ed.). Gaithersburg: National Institute of Standards and Technology. p. 45. https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication811e2008.pdf. "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
- ↑ Efty Abir, Najrul Islam (2016). "How to Calculate Amp Hours – Learn of Convert Watts to Amps". Leo Evans. http://trollingpowersolution.com/how-to-calculate-amp-hours/.
- ↑ 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