Electric Glossary

A small glossary of commonly used electrical terms

Alternating Current (AC) - A flow of electrons that periodically reverses direction.

Amperage - An electric current's strength measured in amperes (amps).

Battery - A device that produces electricity from a chemical reaction. Some batteries can convert electricity back into chemical energy and are thus rechargeable.

Capacitor - Two conductors separated by an insulator and used to store electrical energy.

Current - A flow of electrons in a wire or between two points having a difference in potential (such as inside a battery).

Direct Current (DC) - A flow of electrons in one direction, from negative to positive.

Electric Machine - An energy-conversion device that can operate as a motor or generator.

ELECTRODE - A terminal for carrying electric current to or from a battery. The negative electrode that carries electrons out of a battery is called an anode. The positive electrode is a cathode.

Electrolyte - A liquid, gel, paste, or solid compound that conducts current inside a battery.

Induction motor - A motor that uses electromagnetic induction (rather than a physical connection between the stator and rotor windings) to induce an electric current in the rotor, thereby eliminating the troublesome rotating conductors called commutators or slip rings.

Kilowatt per Hour (kWh) - An energy unit commonly used to quantify electrical consumption or battery capacity; equivalent to consuming 1000 watts of power for one hour.

Lead-Acid Battery - The oldest type of rechargeable battery, offering low cost and a good power-to-weight ratio. Here, lead-plate electrodes surrounded by a diluted sulfuric-acid electrolyte sit within a plastic case.

Lithium Ion Battery - A battery with a lithium-based compound for an electrolyte, it has a high energy-to-weight ratio and low discharge when not in use, but also tougher heat challenges. Not all chemistries are safe enough for automotive use. Currently, cell shapes are either cylindrical or prismatic.

Nickel-Metal-Hydride Battery - A battery that uses a nickel cathode, a metal anode, and a hydrogen-based electrolyte. It falls between lead-acid and lithium-ion batteries in cost and energy density. Currently the most popular battery type for hybrid applications.

Parallel Hybrid - A hybrid in which an electric motor powers the wheels in collaboration with an internal-combustion engine. Example: Toyota Prius.

Permanent Magnent - A material such as neodymium that produces a strong, persistent magnetic field. Often used to replace copper-wire windings in the rotor.

Regenerative Braking - Operating an electric motor as a generator to slow a vehicle while converting its motion, or kinetic energy, into electricity for recharging the battery.

Rotor - The moving part of an electric machine.

Series Hybrid - Electric current from an engine-driven generator powers an electric motor driving the wheels. There is no mechanical connection between the engine and the wheels. Example: Fisker Karma. The Chevrolet Volt has both parallel- and series-hybrid modes.

stator - The static portion of an electric machine. Usually fitted with copper windings that produce a magnetic field.

Synchronous motor - An AC motor in which the rotor turns at a speed proportional to the supply-current frequency.

Three Phase Motor - By using three AC currents that are evenly spaced but out of phase with one another, power production is more constant and motor vibration is reduced.

Voltage - An electromotive force. Also, the difference in electrical potential between two points.

Watt - A unit of power; 746 watts are equivalent to one horsepower.