1. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI Navigation Instructions You will need to become familiar with these buttons to navigate this lesson. The forward button will go forward one screen. Click this button when you are ready to proceed from this screen. Notice the cursor change. The back button will go back one screen. When your mouse cursor changes to a pointed hand, a click will cause an action.

2. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI DC CDI Systems

3. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI Objective  The participants will identify the components and their function of a Battery Powered Capacitor Discharge Ignition system. This will be demonstrated by the participants completing a written exam with 80 percent accuracy.

4. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI DC CDI Systems  In the world of personal watercraft the ignition system design has been exclusively self-powered capacitor discharge ignition (AC CDI) systems.  Today, due to new standards of pollution control, the AC CDI system is being replaced by a battery powered CDI (DC CDI) system, which is one of the most efficient ignition systems available today.

5. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI DC CDI Systems (cont’d)  The DC-CDI ignition system is similar to an AC CDI system except that the battery is used as the source instead of an AC source (exciter) coil.  In addition, except for the DC-DC converter, the DC- CDI ignition control module is identical to the AC CDI unit.

6. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI DC CDI Systems (cont’d)  There is a capacitor in the black box that's charged to several hundred volts by a DC to DC converter (electronic oscillator) that steps up the 12 volts DC from the battery.

7. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI Capacitor Charge Battery Volt (12v). 220 Volts 220 volts capacitor charge

8. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI DC CDI Systems (cont’d)  Then, at the right time, a switch (magnetic) that's actuated by a disk on the end of the crankshaft puts out a pulse that causes the SCR (also in the black box) to dump the capacitor's several hundred volts into the coil.

9. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI Ignition Pulse Generator 2 ~ 3 Volts

10. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI Capacitor Discharge 220 volts 220 volts capacitor discharge Inducing voltage into the secondary coil

11. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI DC CDI Systems (cont’d)  The coil (acting as a transformer) takes the 220 volt pulse and transforms it to approximately 30,000 volts for the spark plug.

12. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI Secondary Current Loop 30 Kv spark

13. DC CDI Theory ©UTI, Inc.SEA DOO DC CDI End