Automotive Electrical Notes PHS Auto 2 Basic notes for auto shop class study and refer back to your...

Automotive Electrical Notes Automotive Electrical Notes PHS Auto 2PHS Auto 2

Basic notes for auto shop classBasic notes for auto shop class

study and refer back to your text bookstudy and refer back to your text book

Electron theory the electrical phenomenon is produced

by a flow of electrons from one area to another.

The flow of electrons is caused by having an excess number in one area, shortage in anothersurplus negativeshort supply positive

Flow of electronsFlow of electrons

Matter

Anything that takes up space and has mass: solid, liquid or gas

Molecule

Smallest portion of matter and retain all original properties of the original matter, it is made up of atoms

Atoms 100 + different types One molecule of water, is made up of one

atom of oxygen, two atoms of hydrogen H20

Atom make up

PROTON - positive charge + ELECTRON - negative charge - NEUTRON - no charge (neutral)

If there are more protons in the atom then electrons, it is a positive charged atom.proton and neutron in center; electrons orbit

Size of atom ?

Bound electrons

Are in the inner orbits, Bound electrons are very difficult to remove from their orbit.

Free electrons

Outer orbits only, one, two or three electrons, are easily knocked out of their orbit

Conductors Have 1-3 electrons in outer orbit, (Free

electrons)easily knocked out of orbit. Materials such as silver, copper, aluminum, gold make good conductors.

Semi-Conductors 4 electrons in outer orbit

Not a good conductor Not a good insulator

Non conductors Insulators, 5 or more electrons in outer

orbit, glass, ceramics, plastics, rubber, fiber, porcelain, paper and wood are common Insulators. Hard to knock the electrons out of orbit if they have a strong magnetic pull to the protons in the nucleus of the atom.

Current

Movement of free electrons through a conductor current flow is measured in amperes(Amps). Must have shortage of electrons at one end, surplus at other one electron does not go the whole distance moves and bumps others.

Voltage (electromotive force, EMF)

Pressure differential causes current to flow, this pressure is known as voltage

Voltage is a measure in volts with voltmeter.

Resistance Caused by electrons bumping into other

atoms, a poor conductor has greater resistance than a good conductor. Poor conductors will heat up (like a heater).

Larger conductors (wire size) offers less resistance then a smaller one,

Resistance is measured in ohms Current will flow in the one path with least

resistance. Current will flow from negative to positive,

negative has surplus of electrons, positive has short supply.

Which way does it flow ? Ask the experts

Circuits Must have a power source. A load (something to operate such as a

light bulb or motor) Wiring for path of electron flow

(Conductor) Switch Circuit protection

Thanks Kevin http://www.autoshop101.com/

Series circuit, only one path for current to flow

Series CircuitSeries Circuit

Parallel circuit, more than one path for current to flow, current flows through all units at once.

Parallel CircuitParallel Circuit

Series parallel, combination of both circuits.

Series ParallelSeries Parallel

Circuit ProblemsCircuit Problems Open circuit, Wire is broken Short to ground, Wire is touching ground Short to voltage, wire is touching a hot

wire. Load device is on even though switch is off.

High resistance, current is being slowed by corrosion or a poor connection

Car frame Acts as a ground wire, some cars like a

corvette have to run ground wires because of fiberglass body

Ground symbol:

Ohms law

Amperes = I - Intensity Volts = E - Electromotive force Ohms = R - Resistance

to find E = I x RI = E / RR = E / I

I X R

E

Ohms laws For Auto Techs

Some Auto Techs will use the following Amperes = A - Amps Volts = V - Volts Ohms = R - Resistance

to find V = A x RA = V / RR = V / A

A X R

V

M, m, K, M, m, K, μμ

PrefixPrefix SymbolSymbol FactorFactor NumericallyNumerically NameName

gigagiga GG 101099 1 000 000 0001 000 000 000 billionbillion

MegaMega MM 101066 1 000 0001 000 000 millionmillion

kilokilo kk 101033 1 0001 000 thousandthousand

centicenti cc 1010-2-2 0.010.01 hundredthhundredth

millimilli mm 1010-3-3 0.0010.001 thousandththousandth

micromicro μμ 1010-6-6 0.000 0010.000 001 millionthmillionth

nanonano nn 1010-9-9 0.000 000 0010.000 000 001 billionthbillionth

MagnetismMagnetism Materials that have this are called MagnetsMaterials that have this are called Magnets Some are NaturalSome are Natural Some are madeSome are made

Magnetic Domains These small sections of a magnet must

all line up to be a strong magnet.If not, they will cancel each other out and the piece of metal will be unmagnetized

Lines of Force Leave north pole, enter south Unlike poles attract Like poles repel Left hand rule, know which way current

flows, fingers point in direction magnetic field is moving

Magnetic fields surround any conductor carrying an electrical current

Lines of Force

magnetic effects of parallel conductors, magnetic effects of conductors with

current flowing in opposite direction, spark plug wires

magnetic field in coils compared to single wire left hand rule for coils thumb points north

soft iron core in coils, lines of force increase several hundred times

Solenoid can be used to push or pull iron core if

off set will be drawn into the middle

Battery Electro Chemical Device

4 functions 1. provides electrical energy to start car. 2. provides electrical energy to ignition system 3. provides electrical energy to accessories when

demands exceed alternators output 4. voltage stabilizer absorbs abnormal voltages

created by electrical components

Top postTop post Side post Side post

side and side and top posttop post

A side and top post is becoming very A side and top post is becoming very common today because it will fit so common today because it will fit so many cars.many cars.

Batteries a little history

Up to 1955 most batteries were 6 volt General Motors started the move to 12

volts, Volkswagen was the last in 1966 to switch over.

By 2010 some cars may have a 42V/14V System. Several problems lie in wait such as cost of the components. Life of batteries & arcing between components.

Battery Construction Elements consist of two groups of

plates one more negative than positive plates

with insulated separators in between usually 9, 11, or 13 plates. 54, 66, or 78

total. case is made of hard rubber (rough

service) or plastic (light service)

one element in each cell, connected to the adjoining element, connected in series, each cell produces about 2.1 volts

case is divided into 6 cells (12.6 volts) case is divided into 3 cells (6.3 volts)

Electrolyte64% water 36% Sulfuric acid

H20-water 64% specific gravity 1.00 H2S04-sulfuric acid 36% specific gravity

1.835 - caution electrolyte 100% specific gravity 1.270

Charged positive plate negative plate

electrolyte H2S04

pb02 pblead peroxide lead

Discharge oxygen and hydrogen form water, lead and sulfate

form lead sulfate pbso4 H20 pbSo4

Charging send electrons through opposite way reversing the cycle

Sulfated plates refer to plates harden with lead sulfate

Slow long charge to correct sulfated plates sometimes can't

Little brown particles floating around can short out battery (flakes off of the sulfated plates )

Batteries can freeze if discharged H2O is water

Charging battery emits oxygen and hydrogen gas - can explode

To replace add distilled water

Battery types WET CHARGE shipped with electrolyte

must charged during storage DRY CHARGE shipped empty

manufacture gives forming charge dries the cell elements and seals it. If you keep moisture out it will remain fully charged for long time. When needed just add electrolyte

Group size Batteries come in many different group sizes. A

battery's group size simply determines it's length, width, height, and terminal configuration

Will have a number like group 75,78 or 24 or 24F, 26, 34

Battery capacity 1) Plate size, the case same size, plates

are different size Larger plates more amps

2) Number of plates 3) Amount of acid in electrolyte and

battery additives increase the sulfuric acid content of battery

Battery capacity rating Cold Cranking Amperes CCA most common

“Number of amperes load of battery will maintain at 0 degrees Fahrenheit for 30 seconds without battery voltage falling below 7.2 volts” (1.2 volts per cell)

Size of engine should be smaller than cold cranking ampere

Do not be misled by CA that’s just Do not be misled by CA that’s just cranking amps. It will give you a higher cranking amps. It will give you a higher reading but it misleads you because it is reading but it misleads you because it is tested at a higher temperature.tested at a higher temperature.

Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).

Recommended Minimum Recommended Minimum battery sizebattery size

4-cylinder 400 CCA

6-cylinder 500 CCA

8-cylinder 575 CCA

Battery checking visual Inspection

Battery checking visual Inspection

Cracked or leaking caseliquid level, add water use distilled water preferred (No minerals) or ice melted out of a freezer

Voltage can discharge across top from post to post

Clean battery top and post and cables, battery hold downs

visual Inspection

Mix baking soda and water to clean batteries

Clean post and cable with a terminal brush or post cutter

Coat all connections with grease or use a spray like NOCO NCP-2 Battery corrosion spray

Cleaning The Battery

Battery leakage test Battery leakage test Voltmeter – lead at negative postVoltmeter – lead at negative post Voltmeter + lead drag across batteryVoltmeter + lead drag across battery

No voltage should be present anywhere if it No voltage should be present anywhere if it is clean the battery.is clean the battery.

Battery Open Circuit Voltage TestBattery Open Circuit Voltage Test Measure what the voltage is with the key off Measure what the voltage is with the key off

Find out it’s state of charge. It is a good Find out it’s state of charge. It is a good starting point, should be at least 12.66 voltsstarting point, should be at least 12.66 volts

12.66 = fully charged12.66 = fully charged 12.4 = 3/4 charged12.4 = 3/4 charged 12.2 = 1/2 charged12.2 = 1/2 charged 12.0 = 1/4 charged12.0 = 1/4 charged

Battery Terminals & BoltsBattery Terminals & Bolts Post or top terminalPost or top terminal Side terminalSide terminal L terminal used on importL terminal used on import MarineMarine

Terminal TestTerminal Test This is the first step.This is the first step. Take a voltmeterTake a voltmeter DVOM (Digital volt ohm DVOM (Digital volt ohm

meter)meter) Turn to DC VoltsTurn to DC Volts Hook up like picture on Hook up like picture on

next page.next page.

Terminal TestTerminal Test This is just a voltage drop test done on This is just a voltage drop test done on

the battery terminals. You must disable the battery terminals. You must disable the ignition and crank over the engine. the ignition and crank over the engine. Should be under .2 volts. Should be under .2 volts. Make sure you do both Make sure you do both terminals Positive & terminals Positive &

NegativeNegative

Battery Drain test

Battery Drain Key off Hook up a ammeter in series reading

should not exceed the following 77 older cars .01 amps, 10 ma

(milliamps) 78-85 .02 amps-.025 amps, 20-25 ma 1986 & newer .05 amps, 50 ma

Testing specific gravity Hydrometer check before adding water

fully charged battery should read 1.270 should not vary more than 50 points between cells if it does recharge and check again

Maintenance free batteries are sealed, cannot get into some. No way to add water or check specific gravity.

Charging batteries

Clean up first Unhook cables - check liquid level Don't charge over 16 volts if plates are

sulfated or if battery has been discharged for some time

Slow charge for a long period 24 hoursdon't allow temperature to exceed 100

Never fast charge batteries

Most batteries in cars are 12 volt with negative ground.

6 volt older cars and 18 wheelers may have positive ground

SAFETY: do not allow battery acid to contact eyes skin or fabrics if you do flush with lots of water, and get teacher or medical help flush eyes for 15 minutes

Jump starting cars positive to positive negative to negative Hook up negative cable last on car with

dead battery on a good ground. Not on the battery. If sparks occur no Hydrogen to blow up

battery date tags

Did You Know Batteries Lose PowerDid You Know Batteries Lose Power While Sitting on the Shelf? While Sitting on the Shelf?

A battery can permanently lose some of its capacity when it's stored in a partly or fully discharged state. Periodic charging during storage can minimize the deterioration, but not all battery distributors and dealers do the necessary charging. That's why you may want to know how to read the date codes, which show when the product was manufactured, on a new product, to help you make sure you're really buying a fresh battery.

So, how do you read a date code?

Most Brands of BatteriesJOHNSON CONTROLS, INC. - INTERSTATE BATTERIES, Motorcraft, East penn - Deka, GNB -Champion, Stowaway:

The letters and numbers are on a sticker affixed to the battery or hot-stamped into the case cover along the top edges of the battery. The ship date codes begin with a letter: A stands for January, B for February and so on (some shipping codes skip the letter I, so it cannot be confused with the number 1. In those cases, J would represent September, K - October, L - November and M - December). The next digit is a number which represents the year the battery was shipped. Therefore, an A6 would mean the battery was shipped in January of 1996.

Exceptions DELCO - Freedom, Voyager, and some Sears brands:The code dates are stamped on the cover, usually near the posts. The first character represents the year (0-9) and the second shows the month (A-M, skipping I). For example, 4CN1 would stand for 1994, March.

EXIDE - Napa Legend, Edge, Power-Tron and Titan:

The fourth or fifth character may be a letter code for the month and the following character a number code for the year (i.e. RO8F3B stands for June 1993)

Last 3 pages © 2000 Interstate Battery System of America, Inc.

Always Disconnect the ground cable first. (Negative Cable on cars)

Always hook up the ground cable last

If you disconnect the positive first and touch ground you will have sparks.

Removing Batteries

Hooking batteries in series Voltage goes up

Hooking batteries in parallel Voltage stays the same amperage goes up

GeneratorGenerator Electromagnetic device, produces

electricity to run accessories and charge battery

If wire is passed through magnetic field voltage is generated

If passed in the opposite directioncurrent flow reversed

To increase volts and amps 1. increase strength of magnetic field 2. increase the speed wire moves

through the magnetic field

Basic AC operation current flows positive, negative

Basic DC operation

Current flows one way, accomplished by split ring

Charging Indicators ammeter

indicator light

Voltage Monitor

Alternator

Alternators

More efficient at lower speeds Lighter - aluminum construction Requires only 2 or 3 amps passing

through slip rings compared to high amperage in D.C. generator

Governs its own maximum current output

Alternator Generators - moving conductor through

stationary field to induce voltage Alternator - a permanent magnet is rotated

inside a stationary conductor

maximum voltage occurs when conductor cuts heaviest lines of force

Parts of a Alternator

The EndThe End

Pictures from SalsIllustrations from ChryslerScanned images from ModernAutomotive Technology and John Deere