 These systems use a transistor to switch the charging current to the coil off and on at the appropriate times.This eliminated the problem of burned and worn points, and provided a hotter spark because of the faster voltage rise and collapse time in the ignition coil.The DC-CDI module is powered by the battery, and therefore an additional DC/AC inverter circuit is included in the CDI module to raise the 12 V DC to 400-600 V DC, making the CDI module slightly larger.