Lesson Notes By Weeks and Term v4 - SHS 3
INTRODUCTION TO VEHICLE TECHNOLOGY
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INTRODUCTION TO VEHICLE TECHNOLOGY
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Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 5
Grade code: 3.1.2.LI.2
Strand code: 1
Sub-strand code: 2
Content standard code: 3.1.2.CS.1
Indicator code: 3.1.2.LI.2
Theme: AUTOMOTIVE TECHNOLOGY
Subtheme: INTRODUCTION TO VEHICLE TECHNOLOGY
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Welcome, students. Every day, we see and use vehicles like private cars, trotros, buses, and Aboboyaas (tricycles). But have you ever wondered what brings them to life? Beyond the engine, a vehicle has a complex "nervous system" – its electrical system. This system powers everything from the lights that keep us safe at night to the radio that plays our favourite hiplife tunes and the horn we use on busy roads in Accra or Kumasi. Understanding these systems is not just for mechanics ('fitters'); it's crucial for any driver to identify problems early and ensure safety on our roads. Today, we will explore the four fundamental parts of this electrical system.
The electrical system of a vehicle is a closed circuit with its own power source. It is responsible for starting the engine, powering all the lights, charging the battery, and operating all the accessories. We will focus on four key sub-systems. A. The Charging System
This is the heart of the vehicle's electrical power generation. Its main job is to recharge the battery and provide electricity to all other systems when the engine is running. Think of it like this: the battery is like a power bank used to start the car, but the charging system is like the ECG grid that powers everything while the car is "on" and recharges the power bank at the same time.
Key Components: The Battery: Function: A chemical device that stores electrical energy in the form of Direct Current (DC). In most cars, it's a 12-volt battery. Its primary job is to provide the powerful burst of electricity needed to turn the starter motor and start the engine. When the engine is off, the battery powers everything (e.g., radio, interior lights). The Alternator (Dynamo in very old cars): Function: This is the vehicle's own power plant. It is driven by a belt (the fan belt or serpentine belt) connected to the engine's crankshaft. As the engine runs, it spins the alternator, which converts mechanical energy into electrical energy. It produces Alternating Current (AC) which is then converted (rectified) to Direct Current (DC) to be used by the car. Analogy: The alternator is like the Akosombo Dam for the car. The engine's motion is the water flow, and the alternator is the turbine generating electricity. The Voltage Regulator: Function: This is the 'brain' of the charging system. Its job is to monitor the battery's charge level and control the alternator's output. If it didn't exist, the alternator would keep pumping electricity into the battery until it overcharged and got damaged (like overfilling a bucket with water). It ensures the voltage stays at a safe level, typically between 13.5 and 14.5 volts.
How It Works (Step-by-Step): Engine Off: The battery is the sole power source. Starting: The battery delivers a high current to the starter motor. Engine Running: The engine belt spins the alternator. The alternator starts generating electricity. Power Distribution: The electricity from the alternator now takes over. It powers all the electrical systems (lights, radio, A/C) and sends any excess current back to the battery to recharge it. Regulation: The voltage regulator constantly checks the system's needs and tells the alternator to produce more or less electricity. B. The Lighting System