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What Voltage Is the Battery in a Car?

by Andrea Stein

A car battery refers to a form of rechargeable battery used to provide power in the form of electric energy to the starter motor, ignition system and lights in a car. Car batteries must supply a certain level of voltage to carry out this function.

Nominal Voltage

Car batteries generate a nominal 12-volt potential difference, or the voltage supplied by two points in an electric field. These 12 volts occur via the connection of six galvanic cells, or cells that are electrochemical in nature and draw energy from chemical reactions occurring within the cell. Each galvanic cell provides 2.1 volts, and combine to generate 12.6 volts in the car battery at full charge.

Charging System

During engine cranking, a car’s charging system restores charge to the battery. The voltage regulator contained in this the system supplies an average voltage amount of between 13.8 to 14.4 volts. The voltage provided to the car battery decreases as the battery recharges.

Battery Failure

Battery faults, or loss of charge, results from such causes as broken terminals, low electrolytes or damaged internal connections due to corrosion. An internal battery fault typically necessitates replacement of the car battery unit.

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