Lesson Notes By Weeks and Term v3 - Senior Secondary 3
Electrical parts
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Electrical parts
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Subject: Autopart Merchandizing
Class: Senior Secondary 3
Term: 1st Term
Week: 7
Theme: Automobile Parts
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List electrical part/ components of an automobile Identify the electrical parts State the functions of the electrical parts.
The electrical system of an automobile is responsible for generating, storing, and distributing electrical energy to power all the vehicle's electrical components.
It can be broadly categorized into: Starting System: Initiates engine rotation.
Charging System: Generates electricity and maintains battery charge.
Ignition System: Ignites the fuel-air mixture in the engine cylinders.
Lighting System: Provides illumination and signaling.
Accessory System: Powers all other electrical features (e.g., radio, wipers, power windows). This section details common electrical parts, their descriptions, and functions. 2.
1. The Battery Description: A rectangular lead-acid electrochemical cell (or sometimes Lithium-Ion in modern vehicles) usually located in the engine bay or boot. It has two terminals, a positive (+) and a negative (-).
Function:
1. Stores chemical energy and converts it into electrical energy.
2. Provides the initial surge of electrical power to the starter motor to crank the engine.
3. Supplies power to vehicle accessories when the engine is off.
4. Acts as a voltage stabilizer for the entire electrical system.
Relevance: Essential for starting the vehicle; a weak or dead battery is a common cause of vehicle breakdown in Nigeria. 2.
2. Alternator Description: A cylindrical device, typically mounted on the side of the engine and driven by a serpentine belt connected to the engine crankshaft. It usually has cooling fins and electrical connectors.
Function:
1. Generates alternating current (AC) electricity (which is then converted to direct current, DC, by built-in rectifiers) to power the vehicle's electrical systems once the engine is running.
2. Recharges the vehicle's battery.
Relevance: Crucial for maintaining vehicle operation and preventing battery discharge; a faulty alternator can leave a driver stranded. 2.
3. Starter Motor (Commonly referred to as "Kick Start" in Nigerian parlance)
Description: A powerful electric motor, cylindrical in shape, usually located near the engine's flywheel/flexplate housing. It often has a smaller cylindrical component attached to it, which is the solenoid.
Function:
1. Uses a large amount of current from the battery to rotate the engine's crankshaft, initiating the combustion process and getting the engine to start.
2. The solenoid pushes the starter gear (bendix gear) to engage with the engine's flywheel and simultaneously completes the circuit for the starter motor.
Relevance: Directly responsible for engine ignition; a non-functional starter motor means the vehicle cannot be started electrically. 2.
4. Spark Plugs Description: Small, ceramic-insulated components with a metal shell and a central electrode, threaded at one end to screw into the engine cylinder head. Modern engines may use a coil-on-plug design where each spark plug has its individual ignition coil.
Function:
1. Ignites the compressed air-fuel mixture in the combustion chamber through an electrical spark, driving the engine's pistons.
Relevance: Critical for engine power and fuel efficiency; worn-out spark plugs can lead to misfires and poor fuel economy, a common issue in many Nigerian vehicles. 2.
5. Fuses and Relays Fuses: Description: Small, replaceable safety devices, often blade-type (plastic with two metal prongs) or cartridge-type, housed in fuse boxes located in the engine bay or dashboard. They come in various colours, each indicating a specific amperage rating.
Function: Protect electrical circuits and components from damage due to excessive current (overload or short circuit) by melting and breaking the circuit.
Relays: Description: Small electromagnetic switches, typically cube-shaped plastic boxes with multiple metal pins at the bottom, found in fuse/relay boxes.
Function: Allow a low-current control circuit to switch a high-current power circuit. This protects the main switches (like the ignition switch or headlight switch) from carrying heavy currents, thus prolonging their life. For example, the horn, headlights, or fuel pump often use relays.
Relevance: Essential for electrical system safety and component longevity; a blown fuse is a common troubleshooting point for non-functioning accessories. 2.
6. Wiring Harness Description: A bundled assembly of electrical wires, cables, and connectors that transmits electrical power and signals throughout the vehicle. These bundles are often wrapped in tape or conduit for protection.
Function: Provides the complete electrical infrastructure, connecting all electrical components (battery, alternator, sensors, lights, etc.) to each other and to the control units. * Relevance: For example, the horn, headlights, or fuel pump often use relays.
Relevance: Essential for electrical system safety and component longevity; a blown fuse is a common troubleshooting point for non-functioning accessories. 2.
6. Wiring Harness Description: A bundled assembly of electrical wires, cables, and connectors that transmits electrical power and signals throughout the vehicle. These bundles are often wrapped in tape or conduit for protection.
Function: Provides the complete electrical infrastructure, connecting all electrical components (battery, alternator, sensors, lights, etc.) to each other and to the control units.
Relevance: The backbone of the vehicle's electrical system; damaged wiring can cause various electrical malfunctions. 2.
7. Lighting Components (Headlights, Tail Lights, Indicators)
Description: Assemblies containing bulbs (incandescent, halogen, LED, or HID) and reflectors, located at various points on the vehicle exterior and interior.
Function:
1. Headlights: Provide illumination for driving at night and increase vehicle visibility.
2. Tail Lights: Indicate the rear of the vehicle, particularly at night.
3. Brake Lights: Illuminate brightly when brakes are applied, signaling deceleration to following vehicles.
4. Indicator Lights (Turn Signals): Flash to signal an intended turn or lane change.
Relevance: Critical for road safety, especially given varying road conditions and visibility in Nigeria. 2.
8. Sensors Description: Small electronic devices found throughout the engine and chassis, designed to monitor specific physical conditions (e.g., temperature, pressure, speed, oxygen levels) and convert them into electrical signals.
Function: Provide real-time data to the Engine Control Unit (ECU) or other control modules, enabling precise control over engine performance, emissions, and other vehicle functions.
Examples include: Oxygen (O2) Sensor Crankshaft Position Sensor Coolant Temperature Sensor Vehicle Speed Sensor Relevance: Modern vehicles rely heavily on sensors for optimal performance and fuel efficiency, issues with which are common complaints in the Nigerian auto market. 2.
9. Engine Control Unit (ECU) / Powertrain Control Module (PCM)
Description: The "brain" of the vehicle, a sophisticated computer module typically located in the engine bay or under the dashboard, with multiple electrical connectors.
Function: Processes data from various sensors and uses pre-programmed maps to control critical engine functions (e.g., fuel injection timing, ignition timing, idle speed, emissions control) and often automatic transmission functions. * Relevance: Central to the operation of modern vehicles; faults can lead to significant performance issues and increased emissions. This section outlines practical activities to deliver the lesson effectively. 3.
1. Teacher Activities: Introduction (10 minutes): Begin by asking students to brainstorm why their phones or flashlights need batteries. Link this to how cars, which are much larger, also need power to operate.
Introduce the topic: "Electrical Parts of an Automobile" and state the learning objectives. Prompt students to list any electrical components they already know in a car.
Presentation and Explanation (30 minutes): Using diagrams, charts, pictures, or actual physical components (if available in the school workshop or from a local mechanic), present each electrical part covered in the "Key Concepts and Explanations" section. For each part (Battery, Alternator, Starter Motor, Spark Plugs, Fuses, Relays, Wiring Harness, Lights, Sensors, ECU), explain: Its physical appearance and typical location in a vehicle. Its primary function using simple, clear language. Its importance to the vehicle's operation, with examples relevant to common vehicle types in Nigeria (e.g., Toyota Camry, Mercedes Benz, commercial buses). Emphasize the interrelationship between different components (e.g., battery powers starter, alternator recharges battery). Demonstration and Identification (25 minutes): If actual parts are available (Alternator, Starter Motor, Battery, Spark Plugs, Fuses, Relays), physically display them. Guide students to identify each part by pointing out its unique features, shape, size, and typical mounting points. Specifically demonstrate how to identify the "Alternator" and "Kick Start" (Starter Motor) as per the evaluation guide. Explain how they look, feel, and where they're typically found. Use large, clear pictures or video clips if physical parts are not available. Interactive Q&A and Discussion (15 minutes): Pose questions to check for understanding. Encourage students to ask questions about parts they find confusing or have seen before. Facilitate a short discussion on the importance of genuine electrical parts versus substandard alternatives often found in Nigerian markets.
Activity Supervision (As needed): Circulate among students during group activities, providing guidance and clarifying misconceptions. 3.
2. Student Activities: Brainstorming (10 minutes): Participate in the initial brainstorming session, listing known electrical car parts. Active Listening and Note-Taking (30 minutes): Pay close attention to the teacher's explanations and descriptions of each electrical part. Take comprehensive notes, including the name, description, and function of each component. Observation and Identification (25 minutes): Observe the physical demonstration of electrical parts. Practice identifying the parts, especially the Alternator and Starter Motor, when shown by the teacher. If in groups, discuss distinguishing features.
Q&A and Discussion (15 minutes): Engage in the question-and-answer session. Ask clarifying questions. Share personal experiences or observations related to vehicle electrical parts (e.g., a time their car battery died). Group Work (Optional, if parts are plentiful): In small groups, students match physical components (or pictures) to their names and functions. One student describes a part, and others try to identify it and state its function. These questions are designed to reinforce understanding of the performance objectives, with immediate feedback through provided solutions.
Question 1: List three (3) electrical components that are absolutely necessary for an automobile engine to start and run.
Solution: Battery: Provides the initial power to crank the engine.
Starter Motor (Kick Start): Cranks the engine to initiate combustion.
Alternator: Charges the battery and powers the vehicle once the engine is running. (Accept Spark Plugs/Ignition System components for engine running after starting).
Commentary: This question checks objective 1 and 3 (listing and stating function implicitly). It highlights the core components for vehicle operation.
Question 2: Imagine you are a salesperson at a major auto parts dealer in Ladipo market, Lagos. A customer asks for the part responsible for "charging the car battery while driving." a) What is the name of this electrical part? b) Describe its typical appearance so the customer can recognize it.
Solution: a) The name of this electrical part is the Alternator. b)
Appearance: It is typically a cylindrical component, often mounted on the side of the engine block. It usually has cooling fins around its body and is driven by a serpentine belt connected to the engine's crankshaft. It will have several electrical connections.
Commentary: This assesses objective 2 (identification through description) and objective 3 (understanding function). It also places the learning in a relevant Nigerian context.
Question 3: You observe a vehicle having difficulty starting. When the driver turns the key, there's only a clicking sound, and the engine doesn't crank. Which two electrical components are most likely involved in this starting issue, and what are their primary roles in the starting process?
Solution: The two most likely electrical components involved are the Battery and the Starter Motor (Kick Start).
Battery: Its primary role is to provide the large surge of electrical current needed to power the starter motor. A weak or dead battery might not supply enough current, leading to only a clicking sound.
Starter Motor (Kick Start): Its primary role is to use the battery's power to physically rotate the engine's crankshaft. A faulty starter motor (or its solenoid) might fail to engage or rotate the engine even with sufficient battery power.
Commentary: This question combines objectives 1 and 3, requiring students to link components to a common fault scenario, demonstrating practical understanding.
Local Auto Repair and Maintenance: Students will observe these electrical parts daily in mechanic workshops across Nigeria, from the common battery terminal corrosion found in commercial vehicles (e.g., danfo buses) to the replacement of faulty alternators in private cars. Understanding these parts allows them to communicate effectively with mechanics or even perform basic diagnostic checks. This knowledge is directly applicable in any Nigerian community where vehicles are repaired. Autopart Merchandizing Business in Nigeria: The ability to correctly identify and explain the function of electrical parts is crucial for success in the competitive Nigerian autopart market (e.g., Ladipo market in Lagos, Ariaria market in Aba). A knowledgeable merchandizer can accurately recommend parts, avoid selling incorrect components, and build customer trust. This directly impacts the economic livelihood of individuals and supports the local economy by ensuring the supply of vital vehicle components.
Vehicle Safety and Performance: Many electrical components, such as headlights, brake lights, horn, and ABS sensors, are directly related to vehicle safety. Understanding their functions helps students appreciate the importance of maintaining these systems for personal safety and the safety of other road users, especially given the varying road conditions and traffic laws compliance in Nigeria. A well-functioning electrical system also contributes to optimal engine performance and fuel efficiency, which is highly valued due to fluctuating fuel prices.