Basic Electricity and Electronics

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.

Current

Voltage and Current

Simple Circuits

A simple circuit consists of

1. A

power source

such as a battery, alternator, or generator.2. A load

is 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-ground

circuit

, the vehicles frame or body serves as an electrical conductor.

A cable is used to connect the frame to the negative battery terminal.

Prevents having to use two wire circuits.

The body and/or frame must be iron or steel for this to work.

Frame-Ground Circuit

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.

Open and Short Circuits

Electrical Switch

A

switch

is normally used to open and close a circuit

Fuses and Ckt Breakers

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.

Relays

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.

Testing Fuses

Troubleshooting Tools

A

jumper wire

is handy for testing switches, relays, wires, solenoids, and other electrical components

Terminals

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 Construction

Battery Hack

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.

Battery Terminals and Cables

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.

Battery Problems

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.

Battery Post Cleaning

Battery Terminal Cleaning

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.

Side Post Adapters

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.

By connecting the last negative jumper cable to a ground away from battery, any spark will be further away from the explosive battery gas.

Do not short jumper cables together or connect them backwards. This could cause serious damage to the charging or computer systems.

Do not assume that red wire connected to the battery is + or the black is -.

If the cables begin to get hot, discontinue the boost immediately: the cables are not heavy duty enough to do the job.

Once the disabled car is running, first remove the negative cable from the engine block of the problem car, then remove the negative cable from the other car.

Finally, remove the positive clamps from both cars.

Jumper Cables

When shopping for booster cables, look for heavy cable with insulated wire that is at least 6 gauge, with 4 gauge being better. (the lower the cable gauge, the thicker the wire).  Make sure that the wire goes all the way through the clamp and is connected directly to the jaw.  If the wire is connected only to the clamp grip, do not buy it.  Good jumper cables will cost more than $20 with professional quality cables costing $30 or more.  There are plenty of cables that cost as little as $5 to $10.  Stay away from those.

Jump Starting

Batteries on newer cars are not always easily accessible, but when this is the case, they will have a battery tap somewhere in the engine compartment. The positive side will usually be clearly marked under a red plastic protective cover.  The negative side may or may not be there, but you can always connect to the engine block or metal brackets that are directly attached to the engine.

Jump Start

Functions of the Charging System

Recharge the battery after engine cranking or after use of the electrical accessories with the engine shut off.

It supplies the cars electricity when the car is running.

Basic Charging System

The

alternator

is the piece that makes the electricity in a running car.

Alternator Construction

Three Types Belts

Charge Indicators

A

charge indicator

informs the driver of the operating condition of the charging system.

An alternator warning light is wired into the charging system so that it will glow when alternator output drops to a specified level.When a charging problem is indicated, you can still drive a short distance to find help unlike an oil pressure or coolant temperature problem which can cause serious engine damage if you continue to drive. The worst that can happen is that you get stuck in a bad location.

Charge Indicators

The voltmeter shows the driver alternator voltage output.

Alternator voltage is usually 13-15 volts.

If the voltage drops below 12.5, it means that the battery is providing some of the current. If this happens for an extended period, the battery will run down and may not have enough of a charge to start the car after shutting it off.

If the voltage ever goes above 15 volts, there is a problem with the voltage regulator.

Charging System Diagnosis

There are four symptoms of charging system problems:

1. Dead battery

2. Overcharged battery- overheats, or frequent water

3. Abnormal noises-grinding, squealing, buzzing4. Indicator shows problems-light glows all the time or there is an incorrect indicator reading.

Alternator Belts

A loose alternator belt may squeal or flap and prevent normal charging.

When inspecting a belt, look for cracks, glazing (hard shiny surfaces), grease or oil contamination, and deterioration.

If needed adjust the belt tension by loosening the alternating mounting and adjusting bolts. Then pry on a strong surface. Serpentine belts have

no adjustment

.

Tighten any other mounting bolts and recheck the belt tension. The belt should deflect

½ inch when pressed with a thumb.

Belt Inspection

Adjusting Belt Tension

Starting System

Starter Parts

Starting Problems

A dead battery is one of the most common reasons the starting system fails to crank the engine.

A

humming noise

that occurs after momentary engine cranking may be to a bad overrunning clutch or a worn pinion gear.A metallic grinding noise

may be caused by broken flywheel teeth or worn pinion gear teeth. The grinding may caused as the gears clash together.

Normal cranking without starting is usually not caused by the starting system.

Starting Headlight Test

A

starting headlight test

will quickly indicate the causes of trouble in a starting system.

Turn on the headlights and try to start the engine. Note any sounds and watch the brightness of the lights.

No cranking with no headlights indicates a dead battery or an open electrical system (blown main fuse).

If the headlights go out when cranking the battery may be weak, the starter bad, or the engine may be at fault.

If the lights stay bright but the engine doesn’t crank properly, a bad ignition switch or neutral safety switch.

This One is Done