CDI Coil

Ignition

109.17
  • EMtron
    • Ignition

Capacitor Discharge Ignition (CDI) Technical Overview

System Fundamentals

CDI systems utilize rapid capacitor discharge (typically 200-600V) through thyristors to generate intense spark pulses. This differs fundamentally from inductive systems by storing energy in capacitors rather than magnetic fields.

Core Components

  • Power Capacitor: 1-5μF high-voltage storage (400V+ rating)

  • Thyristor Switch: 200-1000A peak current handling

  • Step-Up Transformer: 1:100 turns ratio for 20-50kV output

  • Trigger Circuit: Hall-effect or optical crank position sensing

Performance Characteristics

  • Discharge Time: 50-300μs (vs 1-5ms inductive)

  • Spark Temperature: 60,000-100,000K plasma core

  • Recharge Rate: <1ms at 15,000 RPM