Electronics (Gas Engines)

A gas scooter capacitor discharge ignition (CDI) system consists of a battery, CDI module, rectifier, ignition coil, and spark plug.

How It Works
In a DC CDI system, the 12 volt output provided by the scooter battery is increased to 400-600 volts by a transformer inside the CDI module, which in turn charges a high voltage capacitor (a device that stores electrical energy). The rectifier prevents the capacitor from discharging prior to ignition (turning the key).

Upon ignition, the rectifier stops charging the capacitor, allowing the capacitor to transfer the 400-600 volt high voltage charge to the ignition coil.

The ignition coil then increases the 400-600 volts to 20,000-40,000 volts, sufficient to jump the gap in the spark plug. The spark plug provides a spark in the engine combustion chamber, providing an explosion, and the engine comes to life.