Step Up Voltage

One purpose of the ignition system is to step up low voltage supplied by the battery to a high voltage at the spark plug. High voltage is needed to ignite the air-fuel mixture in the combustion chamber. Some of the ignition system components carry low voltage (12-volts, the primary circuit) while others support high voltage (10,000 to 100,000 volts, the secondary circuit). High voltage is created with a coil, a step up transformer.