03DelcoRemy Diagnostic Manual130004222020

Page 6 EXAMPLES DP-1014 .450 2.3 0.00 COIL DIODE DIGITAL DIGITAL OL FIGURE 1-9. Digital Ohmmeter CAUTION On 24-volt systems, use only a carbon pile specifically designed for 24-volt use. A 12-volt carbon pile could be damaged if used in a 24-volt circuit. 1-25. THE BASIC HEAVY-DUTY ELECTRICAL SYSTEM. Today’s basic heavy duty electrical system (See Figure 1-1) consists of batteries (usually three or four, but up to eight connected), a starter, an alternator, a magnetic switch, an ignition switch, a push-button switch, and the required wiring. The batteries provide the high current required by the starter. The magnetic switch controls the battery current to the starter solenoid. The ignition and push-button switches activate the magnetic switch, which in turn energizes the starter. If all functions work properly, the engine will crank. 1-26. The mechanical energy of the running engine provides the power for the alternator. The alternator creates the electrical energy needed to recharge the batteries and power the vehicle’s electrical accessories and loads. DP-1015 FIGURE 1-10. Carbon Pile 1-27 . How well the electrical system components are matched will determine in a large part how effectively and efficiently the system will operate. Another important factor in system design is that system wiring must be adequate to carry the current required by each circuit. 1-28. HEAVY DUTY SYSTEM BATTERIES. The battery, or batteries, in the heavy duty electrical system are devices for storing energy. They convert chemical energy into the electrical energy needed to operate the starter. With the engine running, the alternator supplies electrical energy to the batteries, which they convert into chemical energy and store for later use.