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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.
Using the above example, if a battery rated for 100 ampere-hours at a 20-hour rate has a Peukert constant of 1.2 and is discharged at a rate of 10 amperes, it would be fully discharged in time (), which is approximately 8.7 hours. It would therefore deliver only 87 ampere-hours rather than 100.
The coulomb is defined as the quantity of charge that passes through the cross section of an electrical conductor carrying one ampere for one second. [6] This unit was proposed in 1946 and ratified in 1948. [6] The lowercase symbol q is often used to denote a quantity of electric charge.
The sum of the molecular masses of the reactants is 642.6 g/mole, so theoretically a cell can produce two faradays of charge (192,971 coulombs) from 642.6 g of reactants, or 83.4 ampere-hours per kilogram for a 2-volt cell (or 13.9 ampere-hours per kilogram for a 12-volt battery).
An integrating current meter calibrated in ampere-hours or charge. There is also a range of devices referred to as integrating ammeters. [6] [7] In these ammeters the current is summed over time, giving as a result the product of current and time; which is proportional to the electrical charge transferred with that current.
The volt-ampere (SI symbol: VA, [1] sometimes V⋅A or V A) is the unit of measurement for apparent power in an electrical circuit. It is the product of the root mean square voltage (in volts) and the root mean square current (in amperes). [2] Volt-amperes are usually used for analyzing alternating current (AC) circuits.
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As of the 2019 revision of the SI, the ampere is defined by fixing the elementary charge e to be exactly 1.602 176 634 × 10 −19 C, [6] [9] which means an ampere is an electric current equivalent to 10 19 elementary charges moving every 1.602 176 634 seconds or 6.241 509 074 × 10 18 elementary charges moving in a second.