Flow of Battery Power

The electrical system is what makes everything work!

Components of the Electrical System

Components of the Electrical System

Do you ever wonder how the electrical system works? Let me explain it to you…

The components of the electrical system consist of:

  • Battery
  • Alternator
  • Lights
  • Wiring
  • Ignition Switch
  • Starter
  • Fuses
  • Gauges
  • ECU (electronic control unit)

The electrical system is what makes everything work!

Battery voltage from a fully charged battery is distributed throughout the vehicle by way of wires. These wires vary in thickness and composition. The heaviest WIRING is devoted to the starter system. The starter uses more amperage than any other component in the car.  The battery voltage is supplied to the starter through FUSES when the IGNITION SWITCH is turned to the start position. After cranking for approximately 3-5 seconds, the engine starts. After the RPM stabilizes, the alternator charges the battery at approximately 13.5 volts. The power is also distributed to other components such as the lights, A/C system, Radio, etc.

The supply of voltage to the ECU is reduced to 5 volts DC. The Electronic Control Unit is merely a computer, similar to the one you have at home, that monitors all systems on the car.  Whenever a discrepancy is detected, the self diagnosis function in the ECU determines which component is malfunctioning and isolates that component from the system. At the same time the ECU inputs a signal in place of that component so that the car will still function. At the same time, it turns on the engine check light to signal the driver that something has malfunctioned in the system. A diagnostic computer will tell the technician which component has malfunctioned and reset the ECU after repairs have been performed.

The ALTERNATOR is a device that converts mechanical energy into electrical energy. A belt drives a rotating mass called the rotor inside the alternator that is surrounded by coils of wire and magnets. As the rotor rotates it induces a voltage of about 110 volts AC. A voltage regulator built into the alternator changes the voltage to about 13.5 volts DC and regulates that electrical current to the battery. From the battery, current is distributed to all electrical components in the car through various fuses. A fuse is a small length of wire inside a plastic case that will melt if the electrical current load exceeds a certain preset value, thereby protecting that component.

The STARTER is a device to convert electrical energy to mechanical energy. Voltage is supplied to a coil on the starter motor through the ignition switch. This motor is positioned on the engine near the flywheel. A gear engages the teeth on the flywheel, rotating the engine. After the engine is running the starter is disengaged. Hybrid vehicles have no need for a starter. The  hybrid motor that supplies power to the engine is used to start the engine. A hybrid vehicle uses power from a separate battery to power the hybrid electric motor. This battery pack is configured to produce approximately 144 volts DC to the electric motor between the engine and the transmission. When the car is accelerated, the power pack is used to help power the car up to speed. When cruising speed is reached, or engine breaking is being used to slow the car down,  the motor between the engine and transmission becomes a generator, recharging the battery pack.

The wiring is routed throughout the vehicle. It is usually hidden from view to protect it from harm. The wiring consists of various types of metal conductors and terminals. Some systems are more critical  than others, so this wiring is coated with gold, such as the airbag system, to insure continuous contact, free of corrosion. The body of the car is the path to ground for all the circuits. The wiring is so durable and insulated from external factors, that you can spray the engine compartment with water and not harm any circuits.

On year 2000 and newer vehicles, the wiring acts as a communication medium for the various computers in the car. When the car is turned off, the computers communicate for a short time to ensure all circuits are functioning properly, then the computers nearly shut down. Any touch will “wake up” the computers again.

The gauges function to keep the driver aware of conditions surrounding the vehicle. The speedometer is driven by a speed pulser in the transmission. The tachometer is driven by the ignition system. The various gauges have sensors on and around the engine to keep the driver informed at all times.

The maintenance reminder has evolved. Starting from the 04 Acura and 06 Honda, the maintenance reminder has been designed to give a little more information. The maintenance reminder system keeps tabs on conditions that require a needed service. Through a series of sensors and information stored in the Electronic Control Module, the maintenance minder looks at such variables as driving habits, elapsed mileage, and environment to determine the best time to perform maintenance, showing the information on the dash display. The indicator now shows percentage of oil usage left in the engine.  The system automatically moves up maintenance reminders to coincide with other services. For instance, if a tire rotation is scheduled for 7500 miles and an oil change is due at 9000 miles, the system will delay the tire rotation and move up the oil change to 8300 miles. Oil changes, and related services may come sooner or later depending on the customers driving habits. An engine running at freeway speeds or stop and go driving changes the maintenance requirements and therefore indicated maintenance.

For another humorous opinion, checkout the Smoke Theory perspective.

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