CDI Full Form

Capacitor discharge ignition (CDI), which is also known as the Thyristor ignition system. It is a type of automotive electronic ignition system widely used in outboard motors, motorcycles, lawnmowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It is developed to replace the inductive discharge ignition (IDI) system in which a high induction coil is placed, which takes a long charging time. It is not perfect for high-speed vehicles/engines (small engines, racing engines, and is more suitable for rotary engines). But the Capacitive- discharge ignition (CDI) uses a capacitor discharge current in the coil to fire the spark plug.

( Fig. Capacitor discharge ignition (CDI) system)

Working of CDI

The CDI module includes circuits like a mini transformer & the main capacitor, charging & triggering. The system voltage could be increased from 250V - 600V through a power supply. After that, the flow of electric current will be there toward the charging circuit so that the capacitor can be charged. To run an automobile engine, we need to give the spark inside the cylinder to burn the fuel; so that engine can be started. A capacitor is used to give the electrical energy to the spark plug to perform all these operations. A capacitor discharge ignition works in the engine of an automobile by passing the electrical current into a capacitor. This type of ignition builds up discharge very quickly. A CDI ignition starts with generating a charge and storing it before sending it to the spark plug to ignite the engine. This electric power passes through CDI which has an ignition coil that helps it boost the power by acting like a transformer and allowing the energy to pass through it instead of catching any of it. After the current reaches a very high range up to 25000V- 30000V and is sent to the spark plug to generate the spark and run the vehicle (engine).