Capacitive discharge ignition systems are typically abbreviated to CDI. Instead of using the inductance of the ignition coil to store energy, the 12V supply from the battery is stepped up to around 400-500V and this is stored in a capacitor. To fire a spark, the energy of the capacitor is released into the ignition coil that simply acts as a transformer to step the voltage up.
Tech Articles
Capacitive Discharge Ignition Systems
March 25th, 2010Detonation
April 14th, 2007Not too technical, but pretty funny.
Inductive Ignition Systems
April 14th, 2007This is the type of ignition fitting to almost every production vehicle made today. It is also referred to as a transistor ignition systems. An igniter is used to supply a high current ground for the coils negative terminal (rather than breaker points as used in old ignition systems). Wiring of an igniter and coil is shown below.
