Ampere hour

An ampere hour or amp hour (symbol Ah; also denoted A⋅h or A h) 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 3600 coulombs.[1] The commonly seen milliampere hour (mAh or mA⋅h) is one-thousandth of an ampere hour (3.6 coulombs).

Ampere hour
Duracell rechargeable batteries
Rechargeable batteries
Top: AA battery (2500 mA⋅h)
Bottom: AAA battery (1000 mA⋅h)
General information
Unit systemNon-SI metric unit
Unit ofElectric charge
1 A⋅h in ...... is equal to ...
   SI units   3600 C
   Electrostatic units   1.079253×1013 statC
   Electromagnetic units   360 abC
   Gaussian units   1.079253×1013 Fr


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 measure used in X-ray imaging, diagnostic imaging, and radiation therapy. This quantity is proportional to the total X-ray energy produced by a given X-ray tube operated at a particular voltage.[2] 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 electric tension: 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.[3] Generally, the battery voltage varies during discharge; an average value or nominal value may be used to approximate the integration of power.[4]

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 used in electrochemical calculations also.


  • An AA size dry cell has a capacity of about 2 to 3 ampere hours.
  • 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 requires transfer of at least 2.98 million ampere hours.[5]

See also


  1. ^ "Full Conversion Table (sorted by Category)", 2013, webpage: AM-Conversion-table.
  2. ^ X-ray Safety Handbook, 9.0 Terms and Definitions, VirginiaTech Environmental, Health and Safety Services Archived July 23, 2007, at the Wayback Machine
  3. ^ Efty Abir, Najrul Islam (2016). "How to Calculate Amp Hours – Learn of Convert Watts to Amps". Leo Evans. Retrieved 8 December 2016.
  4. ^ National Research Council (U.S.) (2004). Meeting the energy needs of future warriors. National Academies Press. p. 27. ISBN 0-309-09261-2.
  5. ^ T. L. Brown, H. E. Lemay Jr, "Chemistry the Central Science", Prentice-Hall, 1977 ISBN 0-13-128769-9 page 562

AH and variants may refer to:

Ah!, an exclamation


The AMX-10 RC is a light reconnaissance vehicle built by GIAT. Over 240 are in service in the French Army. In addition, 108 vehicles were sold to Morocco and 12 to Qatar. RC stands for Roues-Canon, or wheeled gun.

The AMX-10 RC should not be confused with the AMX-10P; they share automotive components but otherwise have completely different battlefield roles. The AMX-10RC is usually used for reconnaissance missions in dangerous environments or for fire support.

Battery torque wrench

A battery torque wrench is a battery-operated wrench that can apply a specified torque without effort from the operator. It contains a planetary torque multiplier or a gearbox. A reaction device that absorbs the torque rather than the tool operator. The torque output is adjusted by varying the voltage on the motor. The battery torque wrench is used to remove stubborn nuts, or to apply accurate torque. The gearboxes can have multiplication ratios up to 125:1.

The battery torque wrench is sometimes confused with a standard impact wrench, due to their similar appearance. A battery torque wrench is driven by continuous gearing, and not by the hammers of an impacting wrench. A battery torque wrench has very little vibration, and excellent repeatability and accuracy.

The benefit of a battery torque wrench is its capability to operate independently of an outside power source.

Torque capabilities of battery torque wrenches range from 115 Nm, up to a maximum of 6,500 Nm. (84 Ft lbs - 4794 Ft lbs)

The first large-capacity brushless battery torque wrench was invented in Germany in 2013.

Before the brushless motor with micro electronics was introduced, the battery torque wrench was not as accurate as it could be.

Because of the power limitations of the accurate motor, the tool has 2 speeds: one for speed, and one for power.

Clansman (military radio)

Clansman is the name of a combat net radio system (CNR) used by the British Army from 1976 to 2010.

Clansman was developed by the Signals Research and Development Establishment (SRDE) in the 1960s, to satisfy a General Staff Requirement (GSR) laid down in 1965. Most Clansman radio equipment was built by Racal, Mullard Equipment Ltd (MEL) and Plessey, although headsets and ancillaries were also produced by Amplivox, Marconi and others. Clansman represented a considerable advance over existing radios being offered to the Armed Forces at the time. It replaced the aging Larkspur radio system, and proved to be more flexible, reliable and far lighter. The technological advances in the design of Clansman allowed the introduction of Single SideBand (SSB) operation and NarrowBand Frequency Modulation (NBFM) to forward area combat net radio for the first time.

Clansman was in use by British forces from the late 1970s and saw service in most UK military operations. It was replaced in the mid-2000s by the Bowman communication system.


The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge. It is the charge (symbol: Q or q) transported by a constant current of one ampere in one second:

Thus, it is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt:

The coulomb is equivalent to the charge of approximately 6.242×1018 (1.036×10−5 mol) protons, and −1 C is equivalent to the charge of approximately 6.242×1018 electrons.

A new definition, in terms of the elementary charge, will take effect on 20 May 2019. The new definition defines the elementary charge (the charge of the proton) as exactly 1.602176634×10−19 coulombs.

Electric charge

Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges; positive and negative (commonly carried by protons and electrons respectively). Like charges repel and unlike attract. An object with an absence of net charge is referred to as neutral. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that do not require consideration of quantum effects.

Electric charge is a conserved property; the net charge of an isolated system, the amount of positive charge minus the amount of negative charge, cannot change. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms. If there are more electrons than protons in a piece of matter, it will have a negative charge, if there are fewer it will have a positive charge, and if there are equal numbers it will be neutral. Charge is quantized; it comes in integer multiples of individual small units called the elementary charge, e, about 1.602×10−19 coulombs, which is the smallest charge which can exist freely (particles called quarks have smaller charges, multiples of 1/3e, but they are only found in combination, and always combine to form particles with integer charge). The proton has a charge of +e, and the electron has a charge of −e.

An electric charge has an electric field, and if the charge is moving it also generates a magnetic field. The combination of the electric and magnetic field is called the electromagnetic field, and its interaction with charges is the source of the electromagnetic force, which is one of the four fundamental forces in physics. The study of charged particles, and how their interactions are mediated by photons, is called quantum electrodynamics.

The SI derived unit of electric charge is the coulomb (C) named after French physicist Charles-Augustin de Coulomb. In electrical engineering, it is also common to use the ampere-hour (Ah); in physics and chemistry, it is common to use the elementary charge (e as a unit). Chemistry also uses the Faraday constant as the charge on a mole of electrons. The symbol Q often denotes charge.

Electric vehicle battery

An electric-vehicle battery (EVB) or traction battery is a battery used to power the propulsion of battery electric vehicles (BEVs). Vehicle batteries are usually a secondary (rechargeable) battery. Traction batteries are used in forklifts, electric golf carts, riding floor scrubbers, electric motorcycles, electric cars, trucks, vans, and other electric vehicles.

Electric-vehicle batteries differ from starting, lighting, and ignition (SLI) batteries because they are designed to give power over sustained periods of time. Deep-cycle batteries are used instead of SLI batteries for these applications. Traction batteries must be designed with a high ampere-hour capacity. Batteries for electric vehicles are characterized by their relatively high power-to-weight ratio, specific energy and energy density; smaller, lighter batteries reduce the weight of the vehicle and improve its performance. Compared to liquid fuels, most current battery technologies have much lower specific energy, and this often impacts the maximal all-electric range of the vehicles. However, metal-air batteries have high specific energy because the cathode is provided by the surrounding oxygen in the air. Rechargeable batteries used in electric vehicles include lead–acid ("flooded", deep-cycle, and VRLA), NiCd, nickel–metal hydride, lithium-ion, Li-ion polymer, and, less commonly, zinc–air and molten-salt batteries. The most common battery type in modern electric cars are lithium-ion and Lithium polymer battery, because of their high energy density compared to their weight. The amount of electricity (i.e. electric charge) stored in batteries is measured in ampere hours or in coulombs, with the total energy often measured in watt hours.

The battery makes up a substantial cost of BEVs, which unlike for fossil-fueled cars, profoundly manifests itself as a price of range. As of 2018, the few electric cars with over 500 km of range such as the Tesla Model S are firmly in the luxury segment. Since the late 1990s, advances in battery technology have been driven by demands for portable electronics, like laptop computers and mobile phones. The BEV marketplace has reaped the benefits of these advances both in performance, energy density. The batteries can be discharged and recharged each day. According to Mitsubishi president Osamu Masuko, the battery cost for the Mitsubishi i-MiEV was cut in half between 2009 and 2011. The cost of electric-vehicle batteries was reduced by more than 35% from 2008 to 2014.The predicted market for automobile traction batteries is over $37 billion in 2020.In terms of operating costs, the price of electricity to run an EV is a small fraction of the cost of fuel for equivalent internal combustion engines, reflecting higher energy efficiency. The cost of replacing the batteries dominates the operating costs.

Kilowatt hour

The kilowatt hour (symbol kWh, kW⋅h or kW h) is a unit of energy equal to 3.6 megajoules. If energy is transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt hours is equal to the power in kilowatts multiplied by the time in hours. The kilowatt hour is commonly used as a billing unit for energy delivered to consumers by electric utilities.

Mah (disambiguation)

Mah is the moon figure of Zoroastrianism.

Mah also may refer to:

An alternative spelling of Ma (surname)

mAh, milli ampere-hour, a unit of electric charge

Ljubljana Marshes, occasionally named Mah, meaning "moss" in SloveneLanguages:

Mah, also known as Mann language of West Africa

mah, code for Marshallese language of the central Pacific

Mariner 8

Mariner-H (Mariner Mars '71), also commonly known as Mariner 8, was (along with Mariner 9) part of the Mariner Mars '71 project. It was intended to go into Mars orbit and return images and data, but a launch vehicle failure prevented Mariner 8 from achieving Earth orbit and the spacecraft reentered into the Atlantic Ocean shortly after launch.

Mars 1

Mars 1, also known as 1962 Beta Nu 1, Mars 2MV-4 and Sputnik 23, was an automatic interplanetary station launched in the direction of Mars on November 1, 1962, the first of the Soviet Mars probe program, with the intent of flying by the planet at a distance of about 11,000 km (6,800 mi). It was designed to image the surface and send back data on cosmic radiation, micrometeoroid impacts and Mars' magnetic field, radiation environment, atmospheric structure, and possible organic compounds.After leaving Earth orbit, the spacecraft and the Molniya (rocket) booster fourth stage separated and the solar panels were deployed. Early telemetry indicated that there was a leak in one of the gas valves in the orientation system so the spacecraft was transferred to gyroscopic stabilization. Sixty-one radio transmissions were held, initially at two-day intervals and later at five days in which a large amount of interplanetary data were collected.

On 21 March 1963, when the spacecraft was at a distance of 106,760,000 km (66,340,000 mi) from Earth on its way to Mars, communications ceased, probably due to failure of the spacecraft's antenna orientation system. Mars 1 closest approach to Mars probably occurred on June 19, 1963 at a distance of approximately 193,000 km (120,000 mi), after which the spacecraft entered an orbit around the Sun.

Memory effect

Memory effect, also known as battery effect, lazy battery effect, or battery memory, is an effect observed in nickel-cadmium and nickel–metal hydride rechargeable batteries that causes them to hold less charge. It describes the situation in which nickel-cadmium batteries gradually lose their maximum energy capacity if they are repeatedly recharged after being only partially discharged. The battery appears to "remember" the smaller capacity.

Motorized wheelchair

A motorized wheelchair, powerchair, electric wheelchair or electric-powered wheelchair (EPW) is a wheelchair that is propelled by means of an electric motor rather than manual power. Motorized wheelchairs are useful for those unable to propel a manual wheelchair or who may need to use a wheelchair for distances or over terrain which would be fatiguing in a manual wheelchair. They may also be used not just by people with 'traditional' mobility impairments, but also by people with cardiovascular and fatigue-based conditions.

Oliver B. Shallenberger

Oliver Blackburn Shallenberger (May 7, 1860 – January 23, 1898) was an American electrical engineer and inventor. He is associated with electrical inventions related to alternating current. He is most noted for inventing the first successful alternating current electrical meter, the forerunner of the modern electric meter. This was critical to general acceptance of AC power.


SPURV, or Self-Propelled Underwater Research Vehicle, was an Autonomous Underwater Vehicle built in 1957 at the University of Washington's Applied Physics Laboratory. The research and development of this vehicle was funded by the United States Office of Naval Research (ONR), and it became the US Navy’s first autonomous underwater vehicle (AUV). The navy used a total of 7 SPURV vehicles until 1979.

Sensor node

A sensor node, also known as a mote (chiefly in North America), is a node in a sensor network that is capable of performing some processing, gathering sensory information and communicating with other connected nodes in the network. A mote is a node but a node is not always a mote.[1]

Silver-cadmium battery

A silver-cadmium battery is a type of rechargeable battery using cadmium metal as its negative terminal, silver oxide as the positive terminal, and an alkaline water-based electrolyte. It produces about 1.1 volts per cell on discharge, and about 40 watthours per kilogram specific energy density. A silver-cadmium battery provides more energy than a nickel-cadmium cell of comparable weight. It has higher life cycle expectancy than silver-zinc cells, but lower terminal voltage and lower energy density. However, the high cost of silver and the toxicity of cadmium restrict its applications.

The first silver-cadmium batteries were developed by Waldemar Jungner around 1900, who used them in a demonstration electric car and whose company commercially manufactured the cells. These original cells suffered from short life, and it was not until 1941 that an improved separator material was developed to prevent migration of the silver oxide within the cell. Renewed commercial development occurred during the 1950s, to take advantage of the better cycle life of the silver-cadmium system compared to silver-zinc. Like other silver-oxide battery systems, silver-cadmium batteries have relatively flat voltage during discharge. However, high-rate performance is not as good as for silver-zinc batteries. To preserve the operating life of cells, they may be shipped "dry" and the end-user adds electrolyte just before use.

The positive electrode is made of sintered silver powder pasted onto a silver grid as current collector; the silver oxide may be formed in a separate process or may be formed on first charging of the cell. The cadmium negative electrode is formed of a pasted grid. Electrolytes are solutions of potassium hydroxide in water. Cells are provide with vent caps to prevent reaction of the electrolyte with carbon dioxide in the air. Theoretically as little of two grams of silver are required for each ampere-hour of capacity, but practical cells require between 3 and 3.5 grams. Because the charging voltage is higher than the discharge voltage, the watt-hour efficiency of a silver-cadmium cell is about 70%; ampere-hour efficiency is about 98%. The usual recommended charging method is constant-current charging at a 10 or 20 hour rate, (restoring the capacity of the battery over 10 or 20 hours), and cut off of charging at 1.6 volts per cell. Cells are commercially manufactured from 2 to 2500 ampere-hours capacity, but are often customized for particular uses.

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