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Basic Electricity and Electronics. Objectives. Explain the principles of electricity. Identify basic electric terms and components. Perform fundamental electrical tests. Describe the basic parts of an automotive battery. Discuss safety precautions with working on batteries.
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Basic Electricity and Electronics
Objectives • Explain the principles of electricity. • Identify basic electric terms and components. • Perform fundamental electrical tests. • Describe the basic parts of an automotive battery. • Discuss safety precautions with working on batteries. • Jump start a car using a second battery. • List the basic parts of the charging system. • Test charging system output with a voltage meter. • Describe starter drive operation
Voltage • Voltage is the force, or electrical pressure, that causes electron flow. • This is similar to how water pressure causes water to squirt out of a garden hose. • Voltage is measure in volts.
Current • Current is the flow of electrons from one atom to another. Current may be AC or DC. All automotive electricity is DC. • Just as water flows through a garden hose, electrons flow through a wire in a circuit. • Current is measured in amperes, or amps for short. • An increase in voltage causes an increase in current flow. A decrease in voltage causes a decrease in current flow.
Simple Circuits • A simple circuit consists of • 1. A power source such as a battery, alternator, or generator. • 2. A loadis an electrical device that uses electricity. • 3. Conductors such as wires or metal parts, that carry current between the power source and the load.
Simple Circuits Current can only flow through the system as long as there is a complete path to and from the battery
Frame-Ground Circuit In a one wire circuit or a frame-groundcircuit, the vehicles frame or body serves as an electrical conductor. The body and/or frame must be iron or steel for this to work. A cable is used to connect the frame to the negative battery terminal. Prevents having to use two wire circuits.
Magnetic Field • A magnetic field can be created using electricity. • Whenever current flows through a wire a magnetic field is created. • Magnetism is also used to create electricity. If a wire (conductor) is passed through a magnetic field, an electric current will be generated in the wire. This is called induction. • Magnetism is used to operate many things in an automobile.
Electrical Terms • Open Circuit- a circuit that has an “open” somewhere in it breaking the circuit. No current can flow through the circuit. • Closed circuit- a complete circuit that allows current to flow. • Short circuit- a short is an accidental connection that results in excessive current flow.
Electrical Switch • A switch is normally used to open and close a circuit
Fuses • There are three basic types of fuses used in automobiles: • 1. A cartridge fuse is a small glass cylinder with metal terminals at each end – used in older 70’s cars • 2. A blade fuse has two blades sticking out and is used in most of today’s cars. • 3. An in-line fuse mounts in a small plastic case in one of the circuit wires. It is mostly used on aftermarket accessories. • Fuse rating is given in amps. When replacing a fuse, ALWAYS replace it with a fuse of the same rating.
Circuit Protection- Fuses • Fuse- a fuse has a link that will melt and burn in half to stop current and prevent further circuit damage.
Relays • A relay is an electrically operated switch. • It allows a small dash switch to control another circuit from a distant point.
Fuses are located throughout the entire vehicle. Common locations include the engine compartment, behind the left or right kick panels, or under the dash. Fuses are usually grouped together and are often mixed in with other components like relays, circuit breakers, and fuse elements.
Fuse / relay block covers usually label the location and position of each fuse, relay, and fuse element contained within.
Troubleshooting Tools • A test light is used to quickly check a circuit for voltage.
Troubleshooting Tools • A jumper wire is handy for testing switches, relays, wires, solenoids, and other electrical components
Electronics • Electronics refers to any electrical component , assembly, circuit, or system that uses solid state devices. • Solid State means these devices have no moving parts to wear out. • Solid state components are much faster than electrical components.
Lights • Lights burn out with age. • Light bulbs come in lots of different types so the easiest way to get the right replacement is to take the old one into a parts place and let them match it. • Headlights are replaceable through the back of the light. Don’t touch the halogen bulb with your fingers. The oil will shorten the bulb life.
Battery Principles • An automotive battery is an electro-chemical device that produces and stores electricity. • A battery produces DC voltage which flows in one direction only. • When discharging, chemical energy is changed into electrical energy. • When charging, electrical energy is converted in chemical energy.
Battery Terminals and Cables • Battery terminals provide a means of connecting the battery plates to the car’s electrical system. • Either two round posts or two side posts are used. • The positive post (marked +) is larger than the negative post (marked - ) • The side posts have female threads that accept a special bolt with an easily rounded 8mm head. • The positive battery cable is normally red and connects to the starter. • The negative cable is normally black and connects to ground.
Battery Functions • Operate the starting motor, ignition system, electronic fuel injection system, and other electrical devices during engine cranking and starting. • Supply all electrical power when the engine is not running. • Help the charging system provide loads when current demands exceed the output of the alternator. • Store energy (electricity)for extended periods.
Battery Charge Indicator • A battery charge indicator, also called the battery eye or test indicator shows the general charge condition of the battery.
Temperature Affects As battery temperature drops, battery power is reduced. At low temperatures, the chemical action inside the battery is slowed. Also the motor oil is thicker increasing the amount of current needed to crank the engine.
Battery Precautions • The automotive battery requires special handling. The electrolyte inside the battery is a mixture of sulfuric acid and water. Sulfuric acid is very corrosive; if it gets on your skin it should be flushed with water immediately; if it gets in your eyes, you should immediately flush them thoroughly with water and see a doctor right away. In this situation, time is critical. • If you work with a battery, you should have a mild solution of baking soda and water on hand and wash with that. • Sulfuric acid will eat through clothing, so it is advisable to wear old clothing when handling batteries. • It is also advisable to wear goggles and gloves while servicing the battery. • When charging, the battery will emit hydrogen gas; it is therefore extremely important to keep flames and sparks away from the battery.
Battery Maintenance • A dead battery is a very common problem. Even though the lights and horn might work, there is not enough “juice” (current) in the battery to operate the starter. • Battery maintenance should be done periodically: • Checking the electrolyte level or the indicator eye. • Cleaning battery terminal connections. • Cleaning the battery top. • Checking the battery hold down and tray. • Inspecting for physical damage to the case and terminals.
Cleaning Top of Case Baking soda and water neutralize and remove the acid-dirt mixture.
Battery Terminal Test • A battery terminal test quickly checks for a poor connection between the battery cables and terminals. • Crank the engine. • Put your hands on the terminals and feel for heat. • Any sign of heat indicates a poor connection. • This applies to any poor electrical connection.
Checking Battery Electrolyte • Unlike older batteries, maintenance free batteries do not need periodic electrolyte under normal conditions. • If the level is low in an older battery, fill the cells to the correct level using distilled water.
Battery Chargers • A battery charger is used to re-energize a dead battery. • A slow charger, also called a trickle charger, feeds a small amount of current into the battery. Charging time is longer (about 12 hrs at 10 amps). • However the chemical action inside the battery is improved as the active material is better plated. • A fast charge or boost charger forces a high current flow into the battery for rapid recharging. • If possible, slow charging should be done after a fast charge
Charging A Battery • Before connecting a charger to a battery, make sure the charger is turned off. If a spark ignites any battery gas it could explode. • Make sure that you do not reverse the charger connections on the vehicles charging system or electronics could be damaged. • If you suspect a battery of being frozen (caused by a dead battery in cold weather), do not charge it. Charging a frozen battery can rupture the case and cause an explosion. Allow the battery to thaw first.
The more common reasons for a dead battery are: • Forgetting the headlights turned on after you park the car. • Forgetting a reading light or courtesy light turned on. This is easy to do since most cars have a feature that delays turning off the interior lights after you leave the car, so that you don't notice that you left a light turned on. • A corroded or loose connection between the battery and the cables attached to it. • A defective interior or trunk lamp switch that leaves the bulb lit. • A defective charging system that does not replenish the battery's charge. • An old battery that has lost its ability to maintain a full charge. Batteries have a life expectancy of 3 to 5 years.
Dead Battery • If you aren’t sure what caused your battery to be dead, the first thing you can do is check the battery connections. Touching battery terminals with your hand will not give you a shock since we are dealing with only 12 to 14 volts and it would take more than that before you would feel it. • If however, you touch the battery terminal with anything metal and allow the metal to come into contact with any metal on the car, you will get a severe spark that could cause injury and possibly ignite the hydrogen gas causing an explosion. • Grab each terminal and feel if the connection is loose on the battery. If you notice that one of the terminals is loose, just by moving it, you may be able to establish a good enough connection to start the car by pushing down and twisting the terminal.
Jump Starting • In emergency situations it may be necessary to jump start a vehicle by connecting another battery to the discharged battery. • Connect the red jumper cable to the positive terminal of the dead battery. • Then the red jumper cable to the good battery. • Connect the black jumper to the good battery. • Find a place on the dead car to connect the other negative clamp away from the battery, either on the engine block or a metal bracket that is directly attached to the engine. You most likely will see some small sparking. If you get a big spark, there is something not connected properly.
