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Auto. Basic Electrical

Milwaukee Area Technical College

10-602-101 Automotive Basic Electrical (2cr.) Presenter: David Schwid


Auto. Basic Electrical

Milwaukee Area Technical College

Lesson 2: Atoms •Smallest part of an element •Still has all the characteristics of that element •Can be solid, liquid, or gas.


Auto. Basic Electrical

Milwaukee Area Technical College

Atoms •Atoms consist of three parts: A. Protons (positively charged) B. Neutrons (neutral charged) C. Electrons (negatively charged)


Auto. Basic Electrical

Milwaukee Area Technical College

Atoms Positive and negative charges act like those in a magnet


Auto. Basic Electrical

Milwaukee Area Technical College

Electron flow All Allelectrons electronsdo donot nottravel travelininthe thesame sameorbit. orbit. Some Someare arecloser closerto tothe thenucleus nucleusand andsome someare are farther fartheraway. away. The Theelectrons electronsininthe theouter outerorbits orbits are aresometimes sometimescalled called“free” “free”electrons. electrons. The Theouter outerring ringisiscalled calledaavalance valancering ringand andthe the electrons electronsininthe theouter outerorbits orbitsmay mayalso alsobe be called calledvalance valanceelectrons. electrons. Elements Elementswith with1-3 1-3valance valanceelectrons electronsare are usually usuallygood goodconductors. conductors. Elements Elementswith with44valance valanceelectrons electronsare aresemisemiconductors. conductors. Elements Elementswith with55or ormore morevalance valanceelectrons electrons are areusually usuallygood goodinsulators. insulators.

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Auto. Basic Electrical

Milwaukee Area Technical College

Electricity Definition-

Flow of Electrons

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Auto. Basic Electrical

Milwaukee Area Technical College

Conductors • Allow the flow of electricity • Contain atoms with free electrons – 1 to 3 electrons in the outer orbit

• Free electrons are not locked in orbit around the nucleus – electrons can be forced to move from one atom to another

• Copper, gold, and silver are good conductors


Auto. Basic Electrical

Milwaukee Area Technical College

Semi-Conductor • Allow small amount of electricity to flow – 4 electrons in outer orbit

• Human body is a semi conductor

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Auto. Basic Electrical

Milwaukee Area Technical College

Insulators • Resist the flow of electricity • Contain atoms with bound electrons – 5 to 8 electrons in the outer orbit

• Bound electrons will not leave their orbit around the nucleus • Plastic, rubber, and ceramics are good insulators


Auto. Basic Electrical

Milwaukee Area Technical College

Section 2: Lesson 1 Conductors/Insulators

Conductors are materials that allow current to flow easily. Insulators are materials that are very resistant to current flow. Insulators are used to prevent an unwanted current path.

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Auto. Basic Electrical

Milwaukee Area Technical College

AC/DC

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Auto. Basic Electrical

Milwaukee Area Technical College

Direct Current

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• Direct Current only flows in one direction. • For the purposes of this course, we will say it only flows from positive to negative. Conventional (current) theory


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Milwaukee Area Technical College

Alternating Current

• Alternating Current flows back and forth from positive to negative and from negative to positive. • A/C is produced by a magnetic field passing through a conductor.

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Auto. Basic Electrical

Milwaukee Area Technical College

Lesson 3:

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Electromotive Force Voltage Voltage is the “Electrical Pressure� Voltage is what pushes the electrons through the conductor. It can also be referred to as Potential Difference. Hint: (think water pressure)


Auto. Basic Electrical

Milwaukee Area Technical College

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Amps • Current – Number of electrons that flow past a point in one second – Measured in Amperage • Hint- (think Gallons per Minute)

Amperage Amperageisishow howwe wemeasure measureelectron electronflow flowor or current. current. One Oneampere ampereor oramp ampisis6.25 6.25billion billionbillion billion electrons electronspast pastone onepoint pointininone onesecond! second!


Auto. Basic Electrical

Milwaukee Area Technical College

Characteristics of Current • When current flows through a conductor, it generates heat and magnetism. Energy is only transformed, it is never lost.

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Milwaukee Area Technical College

Resistance

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• Resistance is the opposition to flow of electrons in a conductor. • Measured in ohms (Ω) • Hint- (think water facet)


Auto. Basic Electrical

Milwaukee Area Technical College

Resistance

• There are several factors that affect the resistance of a conductor. They are: – Diameter – Length – Material – Temperature

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Auto. Basic Electrical

Some examples of different wires. – Solid Copper is almost never used. – Hi-Flex 266 used in ABS. – Multi-Stranded is the most common. – Twisted & Shielded used in signal and communications. – Ribbon Wire for space savings.

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Wires

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Milwaukee Area Technical College

Wire Size

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Milwaukee Area Technical College

Wire Stripping & Crimping

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Milwaukee Area Technical College

Soldering

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Milwaukee Area Technical College

Connectors and Terminal Repair

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Auto. Basic Electrical

Milwaukee Area Technical College

Lesson 5: Laws Ohm’s Law

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Auto. Basic Electrical

Milwaukee Area Technical College

Ohm’s Law

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Auto. Basic Electrical

Milwaukee Area Technical College

Ohm’s Law

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Auto. Basic Electrical

Milwaukee Area Technical College

Ohm’s Law

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Milwaukee Area Technical College

Voltage Unknown

E= I x R

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Milwaukee Area Technical College

Resistance Unknown

R= E / I

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Milwaukee Area Technical College

Current Unknown

I= E / R

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Milwaukee Area Technical College

Simple Circuit • Three things – Power supply – Conductor – Load


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Milwaukee Area Technical College

Series Circuit Current is the same throughout the circuit.

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Milwaukee Area Technical College

Series Circuit Rules If voltage remains constant and resistance increases, amperage flow will decrease. If voltage remains constant and resistance decreases, amperage flow will increase.

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Milwaukee Area Technical College

Parallel Circuits The total resistance of a parallel circuit will always be less than the resistance of any of it’s branches.

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Milwaukee Area Technical College

Parallel Circuit Rules The total resistance of a parallel circuit will always be less than the resistance of any of it’s branches. The voltage applied to each branch is the same. The current flow through the branches will be different if the resistance is different. The voltage dropped across each branch will be the same.

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Milwaukee Area Technical College

Parallel Circuits – The voltage applied to each branch is the same.

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Auto. Basic Electrical

Milwaukee Area Technical College

Parallel Circuits The current flow through the branches will be different if the resistance is different.

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Milwaukee Area Technical College

Parallel Branch Amperage As more branches are added, more amperage flows.

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Milwaukee Area Technical College

Series-Parallel Circuit Calculate the total resistance of the parallel circuit first, using the appropriate formula. Add that to the total resistance of the series portion of the circuit. This will give us the total resistance of the circuit. – Now we can calculate the total circuit current flow, because we know what the source voltage is. I=E/R

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Milwaukee Area Technical College

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Circuit Faults • Open- Break in Circuit • Short- Two positive wires touching • Short to Ground- positive wire touching ground • High resistance- Bad connection


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Milwaukee Area Technical College

Open •No completed path to ground – Series circuit – Parallel Circuit

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Milwaukee Area Technical College

Short to Ground •Before the load – – – –

Protection device opens Why? Resistance decreased Current increased

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Milwaukee Area Technical College

Short to Ground •After the load – Load stays on if ground side switched – If close to intended ground, no noticeable effect

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Milwaukee Area Technical College

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Short to Power

•One or more circuits may operate strangely – Figure 8-3, view A, both switches control both loads – Figure 8-3, view B, short to ground


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Milwaukee Area Technical College

Too Much Resistance •Dirt or Corrosion – As resistance increases – Current flow decreases – Voltage needed to operate load drops in another part of the circuit

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Milwaukee Area Technical College

Reading the Meter •

Types –

Digital • •

Manual Ranging Auto Ranging

Analog •

Analog has low internal impedance/allowi ng more current to flow Do Not Use on any computer controlled

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Auto. Basic Electrical

Milwaukee Area Technical College

Units of Measure M = MEGA or 1,000,000 K = KILO or 1,000 m = MILLI or 1/1000th

2.5 M ohms = 2,500,000 ohms .250 M ohms = 250,000 ohms

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Auto. Basic Electrical

Mega

Kilo

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Mega stands for one million and is abbreviated with a capital letter M. One mega ohm equals one million ohms. To convert any value from mega ohms to ohms, move the decimal point six places to the right. For example, 3.5 mega ohms will convert to 3,500,000 ohms. Kilo means one thousand and is abbreviated with a lowercase letter k. A kilo ohm is equal to 1,000 ohms. To convert any value from kilo ohm to ohms, move the decimal point three places to the right. For example, .657 kilo ohms will covert to 657 ohms.

Base Units

Base units are standard units without a prefix. Volts, ohms, and amperes are the primary base units used in electronics. Prefixes are added to base units to change the unit of measurement.


Auto. Basic Electrical

Milli

Micro

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Milli stands for one thousandth and is abbreviated by the lowercase letter m. A milli ampere is onethousandth of one ampere. To convert any value from milli amperes to amperes, move the decimal point three places to the left. For example, 0.355 milli amps will convert to .000355 amps. Micro means one millionth and is abbreviated by the symbol u. A microampere is equal to one millionth of an amp. To convert any value from microamperes to amperes, move the decimal point six places to the left. For example, 355 microamperes will covert to .000355 amps.

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Auto. Basic Electrical

Milwaukee Area Technical College

Reading the Meter

You must know what to expect before taking the reading…….or you’re wasting your time!

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Auto. Basic Electrical

Milwaukee Area Technical College

Lesson 2: Circuit Protection Devices designed to open the circuit in the event of too much current flow. Fuse Fusible Link

Circuit Breaker

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Milwaukee Area Technical College

Switches

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Auto. Basic Electrical

Milwaukee Area Technical College

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Relays A relay is an electric switch that uses a small current to control a larger current. A relay consists of an electromagnet, an armature, and a set of contacts. Some may also contain a clamping diode or resistor. An example of a relay is an A/C clutch relay


Auto. Basic Electrical

Milwaukee Area Technical College

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Relays A control circuit (primary circuit) is used to provide current to the electromagnet. The electromagnet is energized and pulls the armature toward it. The movement of the armature closes the normally open contacts (secondary circuit). When the contacts close they provide a path for current to reach the load.


Auto. Basic Electrical

Milwaukee Area Technical College

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Relays When the electromagnet is de-energized, current reverses and produces a voltage spike. This spike results from the collapsing of the magnetic field around the coil. Voltage spikes can damage electronic components. To prevent this spike, a clamping diode or resistor is wired in parallel with the relay coil, providing a path for this current to return back to the coil without causing harm to the electronic components.


Auto. Basic Electrical

Milwaukee Area Technical College

56

Section 3: Lesson 1 Electrical Measurement DVOM Setup Click on the Following Link for an animated learning object about:

Wisc-Online: Digital Multimeter/Ohmmeter Measurement Connections


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Voltage Testing

1. Available Voltage (Potential) 2. Voltage Drop (Consumption) Options: Milli-Volts D/C D/C Voltage A/C Voltage Always hooked in parallel Reads the voltage difference between the lead ends Amperage must be flowing to measure Voltage Drop Red Lead: Voltage/Ohm PORT Black Lead: COM PORT

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Milwaukee Area Technical College

Amperage Testing A/C or D/C Amperage Options: Milli-Amps/Amps Micro-Amps Red Lead: Amp Port (10 amp max) or milli-amp / micro amp port Black Lead: COM Port Always hooked in Series Amperage must be flowing to measure

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Auto. Basic Electrical Amp Testing Inductive Clamp or “Pick-Up”

Capable of reading 400 Amps Place around 1 wire Not required to place in series Amperage must be flowing to measure Dial set to D/C mV scale Red Lead: Voltage Port Black Lead: COM Port

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Resistance Testing Auto. Basic Electrical

Options: Ohm (Electrical Path Quality) Continuity (Path only)

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The lower the reading the better the path quality OL means “OVER LIMIT” of the meter to read (check the scale the meter is set at) OL means “NO Path of electricity” **The wire or component must be isolated from the power and ground Source** Red Lead: Ohm Port Black Lead: COM Port

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Auto. Basic Electrical

Milwaukee Area Technical College

Diode Testing Performs a continuity test with a higher output voltage to “Turn On” the diode. The meter will read the voltage output Red Lead: Volt/Ohms/Continuity Port Black Lead: COM Port

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Auto. Basic Electrical

Milwaukee Area Technical College

Lesson 1: Symbol Identification Common Symbols

Symbols are used to represent various electrical components. These are referred to as schematic symbols and are used extensively in automotive publications for diagnosing electrical concerns.

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Milwaukee Area Technical College

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Ground Symbol

Because automotive circuits share a common ground, that is, a return path to the battery, a special ground symbol is used to simplify circuit diagrams.


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Milwaukee Area Technical College

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Circuit Protection

Circuit breakers and fuses are two types of circuit protection devices. They are designed to create an open If the specified amount of amps are exceeded.


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Milwaukee Area Technical College

Resistors

Resistors are used to limit current, divide voltage, and in certain applications, generate heat. There are a variety of resistors classified into two main categories: fixed and variable.

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Milwaukee Area Technical College

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Wire and Wire Symbols

Wire is the most common type of conductive material used to connect components. Wire is available in different sizes called gauge size.It is also available in both round and flat types. This is the symbol for wires that cross, but are not connected.


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Milwaukee Area Technical College

Splice

This is the symbol for wires that cross and are connected at a splice.

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Continuation / Optional

A wavy line means a wire is to be continued somewhere else in the circuit. Typically, these lines are used to show a graphically shortened wire.


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Milwaukee Area Technical College

Continuation

An arrow symbol at the end of a wire with a letter inside of it indicates a wire continues as labeled on another page. For example, this wire connects to the generator, but it is shown on another page. The symbol is then repeated on that page. The arrow indicates the direction of current flow.

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Auto. Basic Electrical

Milwaukee Area Technical College

Switch Switches are most commonly used to control a circuit by either allowing or restricting voltage flow. Switches can be mechanical, or electromechanical, or electronic. Switches can be in a multiple of different configurations, such as SPST (single pole, single throw).

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Milwaukee Area Technical College

Battery

A battery provides a source voltage for an electrical/electronic circuit. Most batteries work by the conversion of a chemical reaction into electricity.

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Milwaukee Area Technical College

Motor

A motor provides the conversion of electrical potential into a moving mechanical energy.

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Milwaukee Area Technical College

Light Bulb

A light bulb converts electrical energy into a radiant light. The filament resists electrical flow and heats up, causing the filament to glow.

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Blower Motor Circuits

• Power flow in High Speed – Feed Power – Switched Power – Switched Ground – Hard Ground


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Milwaukee Area Technical College

Blower Motor Circuits

• Power flow in Medium High (M2) Speed – Feed Power – Switched Power – Switched Ground – Hard Ground


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Power Window Circuits

• Power flow with switches off. – Feed Power – Switched Power – Switched Ground – Hard Ground

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Milwaukee Area Technical College

Power Window Circuits

• Power flow with L.F. up.

– Feed Power – Switched Power – Switched Ground – Hard Ground

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Milwaukee Area Technical College

Power Window Circuits

• Power flow with L.F. down.

– Feed Power – Switched Power – Switched Ground – Hard Ground

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Milwaukee Area Technical College

Power Window Circuits

• Power flow with R.F. control down. – Feed Power – Switched Power – Switched Ground – Hard Ground

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Power Window Circuit Diag.

• What voltages should you read at the given points? • Where should you place the leads?


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Milwaukee Area Technical College

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Wiper Motor Circuit

• Power flow with the wipers in low. – Feed Power – Switched Power – Switched Ground – Hard Ground


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82

Wiper Motor Circuit

• Power flow with the wipers in high. – Feed Power – Switched Power – Switched Ground – Hard Ground


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83

Wiper Motor Circuit

• Power flow with the wipers going to park. – Feed Power – Switched Power – Switched Ground – Hard Ground


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Milwaukee Area Technical College

84

Wiper Motor Circuit

• Power flow with the wipers parked. – Feed Power – Switched Power – Switched Ground – Hard Ground


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Milwaukee Area Technical College

Wiper Motor Circuit Diag. • What voltages should you read at the given points? • Where should you place the leads?

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Auto. Basic Electrical

Milwaukee Area Technical College

• An automotive battery is an electrochemical device • It produces and stores direct current electricity


Auto. Basic Electrical

Milwaukee Area Technical College

Batteries The battery provides the electricity to power all systems of the vehicle when the engine is not running. When the engine is running, the charging system supplies all the electricity to power the systems of the vehicle and the battery helps to stabilize voltage for the entire electrical system.


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Milwaukee Area Technical College

Battery Parts


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Milwaukee Area Technical College

Discharging • Changes chemical energy into electrical energy • Stored energy is released

Charging Electrical energy is converted to chemical energy Energy is stored until needed


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Milwaukee Area Technical College

Lead-Acid Battery Cell Electrolyte causes a chemical reaction between the plates, producing 2.1 volts


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Milwaukee Area Technical College

Battery Element

Most automotive batteries have six elements


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Milwaukee Area Technical College

Battery Voltage • Open circuit cell voltage is 2.1 volts • Cells are connected in series • Battery voltage depends on the number of cells • 12 volt battery has 6 cells - open circuit voltage 12.6 volts • 6 volt battery has 3 cells - open circuit voltage 6.3 volts


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Milwaukee Area Technical College

Batteries BATTERY STATE OF CHARGE Once fully charged, a 12 volt battery will produce 2.1 volts per cell. For example, a 12 volt battery = 2.1 volts x 6 cells = 12.6 volts.


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Milwaukee Area Technical College

Battery Voltage


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Milwaukee Area Technical College

Cell Action (Charging) • Alternator causes free electrons to be deposited on the negative (–) plate • This causes the plates to have a difference in potential (voltage)


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Milwaukee Area Technical College

Cell Action (Discharging)

• Load is connected across the terminals • Current flows through the load to equalize the difference in charges on the plates • Excess electrons (current) move from the negative plate through the load to the positive plate


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Milwaukee Area Technical College

Battery Cycling


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Milwaukee Area Technical College

Electrolyte • Mixture of sulfuric acid and distilled water • Poured into each cell until plates are covered • Warning: causes serious burns or blindness, if it comes in contact with your skin or eyes!


Auto. Basic Electrical

Milwaukee Area Technical College

Batteries BATTERY STATE OF CHARGE: With a maintenance possible battery, the technician can check the charge in each cell with a hydrometer. A hydrometer measures the specific gravity of the electrolyte. If the battery is fully charged it will have a specific gravity of 1.265. The lower the specific gravity the weaker the charge.


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Milwaukee Area Technical College

Hydrometer Check • • • •

Measures specific gravity (SG) Compares weight of electrolyte to water Water has a SG of 1.0 Electrolyte in a fully charged battery is more dense with a SG of 1.265 to 1.299 • As a battery becomes discharged, electrolyte has a higher percentage of water, and a lower SG


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• Does not use removable filler caps • Calcium is used to make the plates, reducing gassing • Reduced water loss decreases service requirements


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Batteries BATTERY STATE OF CHARGE


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Milwaukee Area Technical College

Charge Indicator

Changes color to show the general state of charge of the battery


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Milwaukee Area Technical College

Battery Terminals Means of connecting the battery to the vehicle’s electrical system


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Milwaukee Area Technical College

Two-Battery Systems • Parallel – connected negative to negative – connected positive to positive – two 12 volt batteries produce 12 volts, high current

• Series – connected positive to negative – two 12 volt batteries produce 24 volts


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Milwaukee Area Technical College

Battery Cables A. Post-type B. Side terminal C. Braided ground D. 90ยบ post-type E. Solenoid to starter


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Milwaukee Area Technical College

Cable Connections Negative grounds engine block and positive connects to electrical system


Wet- and Dry-Charged Batteries Auto. Basic Electrical

Milwaukee Area Technical College

• Wet-Charged Battery – Filled with electrolyte and charged at the factory – Very common in many locations • Dry-Charged Battery – Contains fully charged elements – Does not contain electrolyte – Leaves the factory in a dry state – Has a long shelf life


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Milwaukee Area Technical College

Cold Cranking Rating

• Determines the current that the battery can deliver for 30 seconds at 0 ºF (-18 ºC) while maintaining terminal voltage of 7.2 volts (1.2 volts per cell) • Expressed as cold cranking amps (CCA) • Indicates ability to crank the engine at cold temperatures • Typical applications: – 305 CCA for small 4 cylinder engine – 450 CCA for 8 cylinder engine


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Milwaukee Area Technical College

Battery Sizes and Ratings • CCA (Cold Cranking Amps) – # of Amps produced in 30 seconds – 0 deg. F – Maintaining at least 7.2V. Don’t confuse CCA with CA!

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Milwaukee Area Technical College

Battery Sizes and Ratings • CA (Cranking Amps) – # of Amps produced in 30 seconds – 32 deg. F – Maintaining at least 7.2V. Don’t confuse CCA with CA!

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Temperature Versus Efficiency


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Milwaukee Area Technical College

Parasitic Loads • Current draw present when engine and ignition are shut off • Computers and clock require constant power • Over prolonged periods, these may discharge the battery enough to prevent starting


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Milwaukee Area Technical College


Auto. Basic Electrical

Milwaukee Area Technical College

Battery Problems Visually inspect batteries for these kinds of problems


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Milwaukee Area Technical College

Battery Leakage Test • Tests for current discharge across the top of the battery • Set a voltmeter to a low voltage range • Use acid-resistant probes • Touch negative lead to negative terminal • Using positive lead, probe top of battery • Clean battery if voltage is above 0 volts


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Milwaukee Area Technical College

Battery Leakage Test


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Milwaukee Area Technical College

Battery Cleaning Wash with baking soda and water, and do not let debris enter filler openings


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Milwaukee Area Technical College

Battery Terminal Test • Tests for poor battery cable connection at battery • Connect negative voltmeter lead to cable end • Connect positive lead to the battery terminal • Disable injection or ignition and crank • Clean connections if voltage is above 0.5 volts


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Milwaukee Area Technical College

Battery Terminal Test


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Milwaukee Area Technical College

Voltage Drop

• Unplanned voltage drop

– An unplanned voltage drop can happen anywhere in a circuit. – In this example “A” represents corrosion in a wire. – The light bulb is dim because the corrosion has consumed too much of the available voltage.

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Voltage Drop

• Unplanned voltage drop

– Many things can cause unplanned voltage drops. Loose connections, corrosion, burned contacts...just to name a few.

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Removing Battery Cables

Different methods of removal


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Milwaukee Area Technical College

Cleaning Battery Posts and Cable Ends

Rotate female end

Use male end of brush on cable


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Milwaukee Area Technical College

Reconnecting Battery Cables Before reconnecting, coat connection with petroleum jelly or white grease


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Milwaukee Area Technical College

Battery Drain Test

• Tests for abnormal current draw with ignition off • Remove battery cable and connect an ammeter in series in the circuit • Disable all lights and clock circuit • Compare ammeter reading to specifications • If reading is high, isolate problem by pulling one fuse at a time


Battery Drain Test

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Typically maximum 10 milliamps (mA)


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Milwaukee Area Technical College

Battery Chargers

• Force current back into the battery to restore the charge on the plates • Change 120 volts AC to 14–15 volts DC


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Slow Charger • Often called a trickle charger • Feeds a small amount of current into battery • Best for long term battery service • Typical slow charge is about 12 hours at 10 amperes


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Fast Charger

• Forces high current flow into battery • Allows engine start from a low battery in a few minutes


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• Connecting a vehicle with a good battery to one with a low battery • Connect positive terminals together with red jumper cable • Connect black jumper cable to a good ground on each vehicle • After starting, remove black cable first • Avoid arcing near the battery


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Jumper Cable Connection Run the engine in the vehicle with the live battery while cranking the other one


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• Measures the current output under load • Determines actual battery performance • Used on batteries with open circuit voltage of 12.4 volts or higher


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Load Tester The most accurate method of determining battery condition

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Milwaukee Area Technical College

Determining Load • Three times the amp-hour rating – 60 amp-hour battery – 60 x 3 = 180 amperes

• One half the cold crank rating – 400 CCA – 400 ÷ 2 = 200 amperes


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Loading the Battery • Turn the load control knob until the ammeter reads the correct amperage • Maintain load for 15 seconds • Read the voltmeter at 15 seconds • Minimum 9.5 volts at room temperature


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Load Test Results If the reading is below the voltage in the chart, the battery is probably bad


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Micro-Type Testers

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• The new standard for battery testing (Click fo • Required by many OEM for warranty • Uses conductance (the ability to conduct current) to measure battery condition • The battery does not need to be fully charged to test.


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3 Minute Charge Test • Determines if the battery is sulphated • Performed if battery is in low state of charge • Charge for 3 minutes at 30-40 amperes • Test voltage while charging • If the voltage goes above 15.5 volts, battery should be replaced


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Milwaukee Area Technical College

3 Minute Charge Test Battery charger and voltmeter are both connected to the battery


8 Basic Electrical (2cr.)