8 Basic Electrical (2cr.)

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical College

10-602-101 Automotive Basic Electrical (2cr.)

Presenter: David Schwid


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


Atoms•Atoms consist of three parts:

A. Protons (positively charged)

B. Neutrons (neutral

charged)C. Electrons (negatively charged)


AtomsPositive and negative charges act

like those in a magnet

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical College 5

Electron flowAll electrons do not travel in the same orbit. All electrons do not travel in the same orbit. Some are closer to the nucleus and some are Some are closer to the nucleus and some are farther away. The electrons in the outer orbits farther away. The electrons in the outer orbits are sometimes called “free” electrons.are sometimes called “free” electrons.

The outer ring is called a valance ring and the The outer ring is called a valance ring and the electrons in the outer orbits may also be electrons in the outer orbits may also be called valance electrons.called valance electrons.

Elements with 1-3 valance electrons are Elements with 1-3 valance electrons are usually good usually good conductors.conductors.

Elements with 4 valance electrons are Elements with 4 valance electrons are semi-semi-conductors.conductors.

Elements with 5 or more valance electrons Elements with 5 or more valance electrons are usually good are usually good insulators.insulators.


ElectricityDefinition- Flow of Electrons

6


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


Semi-Conductor• Allow small amount of electricity to flow

– 4 electrons in outer orbit• Human body is a semi conductor

8


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


Section 2: Lesson 1

Conductors/InsulatorsConductors are materials Conductors are materials

that allow current to flow that allow current to flow easily. easily.

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


AC/DC


Direct Current• 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


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.


Lesson 3:Electromotive Force

VoltageVoltage 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)


Amps• Current

– Number of electrons that flow past a point in one second

– Measured in Amperage

• Hint- (think Gallons per Minute)

15

Amperage is how we measure electron flow or current. One ampere or amp is 6.25 billion billion electrons past one point in one second!


Characteristics of Current• When current flows

through a conductor, it generates heat and magnetism. Energy is only transformed, it is never lost.


Resistance• Resistance is the opposition to flow of

electrons in a conductor. • Measured in ohms (Ω)• Hint- (think water facet)


Resistance• There are several factors that affect the

resistance of a conductor. They are:– Diameter

– Length

– Material

– Temperature


WiresSome 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.


Wire Size


Wire Stripping & Crimping


Soldering


Connectors and Terminal Repair


Lesson 5: Laws

Ohm’s Law


Ohm’s Law


Ohm’s Law


Ohm’s Law


Voltage Unknown

E= I x R


Resistance Unknown

R= E / I


Current Unknown

I= E / R


Simple Circuit• Three things

– Power supply– Conductor– Load


Series CircuitCurrent is the same throughout the

circuit.


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.


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


Parallel Circuit RulesThe 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.


Parallel Circuits– The voltage applied to each branch is

the same.


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


Parallel Branch Amperage As more branches are added, more

amperage flows.


Series-Parallel CircuitCalculate 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


Circuit Faults• Open- Break in Circuit• Short- Two positive wires touching• Short to Ground- positive wire touching

ground• High resistance- Bad connection

40


Open•No completed path to ground

– Series circuit– Parallel Circuit


Short to Ground•Before the load

– Protection device opens– Why?– Resistance decreased– Current increased


Short to Ground•After the load

– Load stays on if ground side switched

– If close to intended ground, no noticeable effect


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


Too Much Resistance•Dirt or Corrosion

– As resistance increases– Current flow decreases– Voltage needed to operate load drops

in another part of the circuit


Reading the Meter• Types

– Digital• Manual Ranging• Auto Ranging

– Analog• Analog has low

internal impedance/allowing more current to flow

• Do Not Use on any computer controlled circuits


Units of MeasureM = MEGA or 1,000,000

K = KILO or 1,000m = MILLI or 1/1000th

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


Mega Mega stands for one million and is abbreviated with a capitalletter M. One mega ohm equals one million ohms. To convertany value from mega ohms to ohms, move the decimal point sixplaces to the right. For example, 3.5 mega ohms will convert to3,500,000 ohms.

Kilo 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.


Milli Milli stands for one thousandth and is abbreviated by the lowercase letter m. A milli ampere is one-thousandth 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.

MicroMicro 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.


Reading the Meter

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


Lesson 2:Circuit Protection

Devices designed to open the Devices designed to open the circuit in the event of too much circuit in the event of too much current flow.current flow.

FuseFuse

Fusible LinkFusible Link

Circuit BreakerCircuit Breaker


Switches


RelaysA 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


RelaysA 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.


RelaysWhen 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.


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

http://www.wisc-online.com/objects/index.asp?objID=AMT2304

http://www.wisc-online.com/objects/index.asp?objID=AMT2304

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical College 57 Voltage Testing1. Available Voltage (Potential)2. Voltage Drop (Consumption)Options:Milli-Volts D/C D/C VoltageA/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 PORTBlack Lead: COM PORT


Amperage Testing

A/C or D/C Amperage

Options:Milli-Amps/AmpsMicro-Amps

Red Lead: Amp Port (10 amp max)or milli-amp / micro amp portBlack Lead: COM Port

Always hooked in SeriesAmperage must be flowing to measure

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical College 59 Amp Testing Inductive Clamp or “Pick-Up”Capable of reading 400 Amps

Place around 1 wire -Not required to place inseries

Amperage must be flowing to measure

Dial set to D/C mV scale

Red Lead: Voltage PortBlack Lead: COM Port

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical College 60 Resistance TestingOptions:Ohm (Electrical Path Quality)Continuity (Path only)

The lower the reading the better the path quality

OL means “OVER LIMIT” of the meterto 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 groundSource**Red Lead: Ohm PortBlack Lead: COM Port


Diode Testing

Performs a continuity test with a higheroutput voltage to “Turn On” the diode.

The meter will read the voltage output

Red Lead: Volt/Ohms/Continuity PortBlack Lead: COM Port


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.


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.


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.


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.


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.


Splice

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


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.


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.


SwitchSwitches 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).


Battery

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


Motor

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


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.


Blower Motor Circuits• Power flow in

High Speed– Feed Power– Switched

Power– Switched

Ground– Hard Ground


Blower Motor Circuits• Power flow in

Medium High (M2) Speed – Feed Power– Switched

Power– Switched



Power Window Circuits• Power flow

with switches off.– Feed Power– Switched

Power– Switched

Ground– Hard

Ground



with L.F. up.– Feed Power– Switched

Power– Switched

Ground– Hard

Ground



with L.F. down.– Feed Power– Switched

Power– Switched

Ground– Hard

Ground



with R.F. control down.– Feed Power– Switched

Power– Switched

Ground– Hard

Ground


• What voltages should you read at the given points?

• Where should you place the leads?

Power Window Circuit Diag.


Wiper Motor Circuit• Power flow

with the wipers in low.– Feed Power– Switched

Power– Switched




with the wipers in high.– Feed Power– Switched

Power– Switched




with the wipers going to park.– Feed Power– Switched

Power– Switched




with the wipers parked.– Feed Power– Switched

Power– Switched



Wiper Motor Circuit Diag.• What

voltages should you read at the given points?

• Where should you place the leads?



• An automotive battery is an electrochemical device

• It produces and stores direct current electricity


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.


Battery Parts


Discharging• Changes chemical energy into electrical

energy• Stored energy is released

ChargingElectrical energy is converted to

chemical energyEnergy is stored until needed


Lead-Acid Battery Cell

Electrolyte causes a chemical reaction between the plates, producing 2.1 volts


Battery Element

Most automotive batteries havesix elements


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


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.


Battery Voltage


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)


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


Battery Cycling


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!


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.


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


• Does not use removable filler caps• Calcium is used to make the plates,

reducing gassing• Reduced water loss decreases service

requirements


Batteries BATTERY STATE OF CHARGE

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical CollegeCharge Indicator

Changes color to show the general state of charge of

the battery


Battery Terminals

Means of connecting the battery to the

vehicle’s electrical system


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


Battery Cables

A. Post-typeB. Side terminalC. Braided groundD. 90º post-typeE. Solenoid to

starter


Cable Connections

Negative grounds engine block and positive connects

to electrical system

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical CollegeWet- and Dry-Charged Batteries

• 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


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


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!


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!


Temperature Versus Efficiency


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



Battery Problems

Visually inspect batteries for these kinds of problems


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


Battery Leakage Test


Battery CleaningWash with baking soda and water, and do

not let debris enter filler openings


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


Battery Terminal Test


• 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.

Voltage Drop


Voltage Drop• Unplanned voltage drop

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


Removing Battery Cables

Different methods of

removal

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical CollegeCleaning Battery Posts and Cable Ends

Rotate female end

of brush on post

Use male end ofbrush on cable

end


Reconnecting Battery Cables

Before reconnecting, coat connection with

petroleum jelly or white grease


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

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical CollegeBattery Drain TestTypically maximum 10 milliamps (mA)


Battery Chargers• Force current back into the battery to

restore the charge on the plates• Change 120 volts AC to 14–15 volts DC


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

Auto. Basic Electrical Auto. Basic Electrical Milwaukee Area Technical CollegeMilwaukee Area Technical CollegeFast Charger• Forces high current flow into battery• Allows engine start from a low battery in

a few minutes


• 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


Jumper Cable ConnectionRun the engine in the vehicle with the live

battery while cranking the other one


• Measures the current output under load• Determines actual battery performance• Used on batteries with open circuit

voltage of 12.4 volts or higher


Load TesterThe most accurate

method of determining battery condition


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


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


Load Test ResultsIf the reading is below the voltage in the

chart, the battery is probably bad


Micro-Type Testers• The new standard for batter

y testing (Click for L.O.)• 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.

http://www.wisc-online.com/objects/framz.asp?objID=AMT1804

http://www.wisc-online.com/objects/framz.asp?objID=AMT1804


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


3 Minute Charge TestBattery charger and voltmeter are both

connected to the battery

Documents

8 Basic Electrical (2cr.)