 However, vehicles that use DC-CDI systems have more precise ignition timing and the engine can be started more easily when cold.A CDI system has a short charging time, a fast voltage rise (between 3 ~ 10 kV/μs) compared to typical inductive systems (300 ~ 500 V/μs) and a short spark duration limited to about 50-600 μs.The fast voltage rise makes CDI systems insensitive to shunt resistance, but the limited spark duration can for some applications be too short to provide reliable ignition.