Basices of Electrical Systems ch.15
What makes a thermistor different from other variable resistors?
It can change it rating, unlike other resistors that are carefully constructed to maintain their rating within a few ohm's through a range of temperatures.
What would parasitic draw do to the battery?
1. cause the battery to lose its charge overnight or after a few days. 2. Can also deplete the battery and cause various driveability problems 3. the computer may go into its back-up mode 4. set false codes 5. raise idle speeds to compensate for low battery voltage
How to conduct a battery load test?
1. make sure battery is fully charged 2. check battery for CCA rating 3. check the temp of battery, should be around 70 degrees F 4. attach testers battery leads to the correct terminals on battery 5. clamp the testers inductive lead around the testers negative cable 6. turn the knob for the ammeter on the tester until the ammeter reads 0 7. rotate the testers load control knob until ammeter reads one-half of the battery's CCA rating 8. after 15 seconds, read the voltage of the battery and turn the load control off 9. then disconnect the tester's leads
What is the procedure to measure the parasitic drains on a battery?
1. make sure the ignition is off and the key is out of the switch 2. turn off all accessories 3. place the ignition switch and all vehicle accessories in the off position, wait 20 minutes after the ignition is off before testing is recommended 4. disconnect the underhood lamp, if equipped 5. set the DMM to read DC amps 6. zero the ammeter 7. place the probe around negative battery cable or insert the meter in series with the cable 8. read the ammeter 9. if the parasitic load is under 2 amps, change the DMM to read mAmps 10. read the ammeter 11. if the parasitic drain is more than the specified maximum, check the trunk, glove box and interior lights to see if they are on 12. if light was on, remove the bulb and watch the battery drain. if the drain is now okay, check that circuit 13. if the cause of the drain is not the lights, find th eproblem circuit by removing one fuse at a time while watching the ammeter. the reading will drop when the fuse on the bad circuit is removed 14. test the components of that circuit to identify the cause of the drain
How do you perform a battery leakage test?
1. set a voltmeter to a low DC volt range. 2. Connect the negative lead to the battery's negative post 3. then move the meter's positive lead across the top and sides of the battery
What do you do if you get a voltage reading when doing a Battery Leakage Test?
1. the battery should be cleaned and then rechecked 2. if voltage is again measured, the battery should be replaced because the case is porous or cracked
How can you measure current drain on a battery?
1. with a DMM connected in series with the negative battery cable 2. by placing a low current probe around the cable. 3. VAT
What is the specific gravity of water?
1.000
What is the specific gravity of a battery?
1.270
How do you use a basic battery hydrometer to measure the electrolyte's specific gravity?
1.Squeeze the hydrometers bulb, which pulls electrolyte into the tube, the hydrometer float bobs in the electrolyte. 2. the depth at which the float sinks in the electrolyte indicates its relative weight compared to water. 3. The reading is then taken off the scale by sighting along the level of electrolyte.
In a parallel circuit what is the current law?
1.the current on each leg will be different if the resistance values are different 2. the sum of the current on each leg equals the total circuit current
How many power or energy sources are used in the automobiles electrical system?
2
How many types of current are there and what are they?
2 and direct current (DC) and alternating current (AC)
What voltage does each cell in a battery produce?
2.1 volts
What is a normal parasitic drain for most vehicles?
30mA
What should a battery's temperature be between?
60 degrees F and 100 degrees F
What is the electrolyte and water percentage of a fully charged battery?
64% water and 36% sulfuric acid (electrolyte)
In wiring diagrams, when the ground is made through the mounting of the component, the connection is represented in the drawing by what?
A
What machine is used to conduct a battery load test?
A VAT or a battery load tester
How does an AC generator work?
A magnetic field, driven by the crankshaft via a drive belt, rotates through a coil of wire, producing electricity
How is the non cycling or resettable circuit breaker that is reset by depressing a reset button operate?
A spring pushes the bimetal arm down and holds the contacts together. When an overcurrent condition exists and the bimetal arm heats up, the bimetal arm bends enough to overcome the spring and the contacts snap open. The contacts stay open until the reset button is, pushed which snaps the contacts together again.
What is used to indicate the types of fuses and sizes of the fuses?
A three- letter code
What is the difference between the peak positive value and the peak negative value used to measure?
AC voltages
Blade fuses have what codes?
ATC or ATO
What is (AWG)?
American wire gauge
What makes up an electrochemical cell?
two electrodes or plates and electrolyte
In wiring diagrams, how is the ground that is made by a wire that connects to the chassis drawn?
B
A car's battery is a source of what kind of energy?
Chemical energy
Engineers often express current flow in?
Coulomb
When the chassis is used for the ground how does the current flow?
Current passes from the battery, through the load, through the metal frame and back to the battery
A chemical reaction in a battery provides for what?
For an excess of electrons and a lack of electrons in another place.
What is a example of a tapped or stepped resistor?
Heater motor resistor packs, which provide for different fan speeds
What is impedance?
In AC circuit's is the actual resistance of a load
What is a voltage limiter also called?
Instrument voltage regulator (IVR)
What is a momentary switch and give a example of one?
Is a type of SPST switch. Is a spring-loaded contact on the switch that keeps it from closing the circuit except when pressure is applied to the button. An example is a horn switch.
What is a relay?
Is an electric switching device that uses a low current load circuit to switch on or off a high current load circuit
What is voltage?
Is electrical pressure, the force developed by the attraction of the electrons to protons. The pressure that causes current flow
What is a carbon pile and what does it do?
Is on a battery load tester and a VAT, is a variable resistor that will draw current from the battery when the tester is attached to the battery
What is the heart of a vehicle's charging system?
Is the AC Generator
What is the formula for determining the amount of power consumed by a load?
Is the amount of current through the load multiplied by the voltage drop across the load.
What is Voltage Drop?
Is the amount of voltage required to cause current flow through a load.
What is the unit for measuring electrical current?
Is the ampere, usually called the amp
What is electricity?
Is the flow of electrons from one atom to another.
How do manufactures ensure good grounding?
Manufacturers use a network of common grounding terminals and wires
How is one of the no cycling or resettable circuit breakers used?
One is reset by removing the power from the circuit. There is a coil wrapped around a bimetal arm. When there is an excessive current and the contacts open, a small current passes through the coil. This current through the coil is not enough to operate a load but it does heat up both the coil and the bimetal arm. This keeps the arm in the open position until power is removed.
How is Power and Watt's law expressed?
P= I x E, power equals current multiplied by voltage
What does an electrical power source provide?
Provides for a more positive charge and to allow for a continuous flow of electricity, it supplies free electrons
How are the different plate groups separated from touching each other in a battery?
Separators are inserted between them
What does SPST mean and an example of one?
Single-pole, single throw. An example is a hinged-pawl switch
What is Ohm's Law?
That it takes 1 volt of electrical pressure push 1 ampere of electrical current through 1 ohm of resistance.
What is electrical energy?
The release of energy as one electron leaves the orbit of one atom and jumps into the orbit of another.
Do all glass SFE fuses have the same diameter, but the length varies with the current rating?
True
Electricity and magnetism are interrelated and can be used to produce the other? True or False
True
The greater the number of electrons flowing past a given point in a given amount of time, the more current the circuit has. True or False?
True
There are two types of manually resetting circuit breakers. True or False?
True
Voltage does not flow? True or False
True
How does the voltage limiter work?
When the ignition is in the on or accessory position, the heating coil heats the bimetal arm, causing it to bend and open the contacts. When them arm cools down to the point that the contacts close, the cycle is repeated.
Looking at a sine wave on a graph, does the highest positive voltage equal the highest negative voltage?
Yes
When a battery quickly losses its charge, what test must be done?
a battery drain test
What are the two power or energy sources of an automobiles electrical system based on?
a chemical reaction and magnetism
What does it mean when a switch is ganged?
a dotted line that shows that they are mechanically linked
What is a plate group?
a group of plates in a battery that holds a number of plates of the same polarity
What does a voltage limiter contain?
a heating coil, a bimetal arm and a set of contacts
What does the chemical reaction in a battery cause?
a lack of electrons at the positive terminal and an excess at the negative terminal.
What is a SPDT?
a single-pole double- throw switch
What instrument is used to measure voltage?
a voltmeter
What do you do to test a AGM battery with a typical conductance tester?
add 100 to the CCA rating of the battery when asked to enter the rating by the tester. If it is not done, all test results will be wrong
How do you correct the specific gravity when using a hydrometer?
adding or subtracting 4 points (0.004) for each 10 degrees F above or below the standard 80 degrees F
What is a plate strap and another name for it?
also called a lead alloy post, is where the like-charged plates are welded together in a battery
What instrument is used to measure electrical current flow in a circuit?
ammeter
What must be present to have a continuous flow of electricity?
an excess of electrons in one place, a lack of electrons in one place and a path between the two places.
What is an open circuit?
an incomplete circuit
What is a thermistor?
another type of variable resistor that is designed to change its resistance value as its temperature changes
What are parasitic loads?
are current drains that exist when the key is off
What are variable resistors?
are designed to have a range of resistances available through two or more taps and a control
What are fixed value resistors?
are designed to have only one rating, which should not change
What are solenoids?
are electromagnets with movable cores used to change electrical current flow into mechanical movement
How are the plate groups placed in a battery?
are placed alternately within the battery, positive, negative, positive, negative and so on
What are separators composed of?
are porous plastic sheets that allow for a transfer of ions between plates
What are solid wires?
are single-stranded conductors
What are stranded wires?
are the most common and are made up a number of small solid wires twisted together to form a single conductor
In a lead-acid battery, what are the plates like?
are typically flat, rectangular components that are either positive or negative, depending on the active material they hold.
What are resistors used for?
are used to limit current flow in circuits where full current flow and voltage are not needed or desired
How are thermistors used?
are used to provide compensating voltage in components or to determine temperature. As a temperature sensor, the thermistor is connected to a voltmeter calibrated in degrees.
What are both the positive and negative plates like?
are very porous and allow the liquid electrolyte to penetrate freely
Why are they called potentiometers?
because different amounts of potential or voltage can be sent to another circuit. As the sliding contact moves, it picks up a voltage equal to the source minus the amount dropped by the resistor, so far
How does a battery load tester or a VAT work?
both have a voltmeter, ammeter and carbon pile 1. when the tester is connected to the battery the carbon pile will draw current from the battery 2. the ammeter will read the amount of current draw from the battery 3. the maximum current draw from the battery, with acceptable voltage, is compared to the rating of the battery to see if the battery is okay
What are series parallel circuits?
both series and parallel combinations exist in the same circuit
Wire size standards were established by?
by the Society of Automotive Engineers (SAE)
How are fuses rated?
by the current at which they are designed to blow
What are the three basic types of fuses in automotive use?
cartridge, blade and ceramic
What causes parasitic draw?
caused by systems that operate when the engine is not running
Most automotive electrical circuits use the ____ as a conductor for the negative side of the battery through the battery's ground wire.
chassis
Batteries are devices that convert what to what?
chemical energy into electrical energy
What are electrochemical reactions?
chemical reactions that produce electrons
How else is electricity produced?
chemical, photoelectrical, thermoelectrical, photoelectrical and piezoelectrical reactions.
What are circuit breakers and how do they work?
circuit breakers conducts current through an arm made of two types of metal bonded together(bimetal arm). If the arm starts to carry too much current, it heats up. As one metal expands faster than the other, the arm bends, opening the contacts. Current flow is broken.
On a relay what is pin 86?
coil battery
On a relay what is pin 85?
coil ground
On a relay what is pin 30?
common feed, where power USUALLY comes inWhay
What are electronics?
computers and other black box-type items used to control engine and vehicle systems.
What test is the only test that will provide accurate measurements of a battery with low SOC?
conductance test
A fully charged battery new battery will have a high _____ reading anywhere from _____ to ______ of its ________
conductance, 110%, 140%, CCA rating
On a relay what are pins 30 and 87?
connected to power and load
On a relay what are pins 85 and 86?
connected to the coil (control circuit)
What does a lead-acid battery consist of?
consists of grids, positive plates, negative plates, separators, elements, electrolyte, a container, cell covers, vent plugs and cell containers.
What is a series circuit?
consists of one or more resistors connected to a voltage source with only one path for electron flow.
As resistance goes up what happens to current?
current goes down
in series circuit what is the current law?
current is constant
What happens if the control switch is opened in a relay?
current stops flowing in the coil and the electromagnet disappears. This releases the armature, which breaks the power circuit contacts
What are the two types of circuit breakers?
cycling or must be manually reset
Blade or spade fuses were used on what vehicles and how are they constructed?
late-model domestic vehicles and many imports
What happens to the specific gravity of electrolyte as a battery discharges?
decreases
What varies the amount of voltage dropped by a load?
depends on the circuit's current and the resistance of the load
What is electrical current?
describes the movement or flow of electricity
How are tapped or stepped resistors designed?
designed to have two or more fixed values available by connecting wires to several taps of the resistor.
In a series parallel circuit, how do you calculate the values?
determine all values of the parallel circuit(s) first.
What does a Battery Load test determine?
determines how well a battery performs under a load
The amount of electricity consumed by a load is normally called?
electrical power usage or watts
What is inside a battery?
electrodes or plates and electroylte
What are the two most common ways of producing electricity?
electromagnetic induction and chemical reaction
How is electric power expressed and what does it represent?
expressed in watts and represents the rate at which electrical energy is converted to another form of energy
Automotive circuits typically contain what type of resistors?
fixed value, stepped or tapped and variable
Using the frame as a return path or ground eliminates the need for what?
for a separate ground wire at each component
Cells in a battery connected in series-parallel provide what?
for increases in voltage and amperage
What are some types of circuit protection devices?
fuses, fuse links, maxi-fuses and circuit breakers
How are the cells in a battery in series-parallel connection connected?
groups of cells are wired in parallel and then those groups are connected in series
How are cells in a battery in series connection connected?
have the positive terminal of one cell connected connected to the negative terminal of another, the positive terminal of that cell is connected to the negative terminal of another and so on
How many wires do potentiometers have and how are they constructed?
have three connections, one at each end of the resistance and one connected to a sliding contact with the resistor.
How many wires do rheostats have and how are they constructed?
have two connections, one to the fixed end of a resistor and one to a sliding contact with the resistor
The resistance to current flow produces what?
heat
Cells in the battery are connected in series to provide what?
higher voltages
What is the simplest type of switch and what does it do?
hinged-pawl and it either makes or breaks current flow in a single conductor
What does the total resistance in a circuit determine?
how much current will flow through the circuit
When performing a battery leakage test, if you get a reading on the meter what does that mean?
if some voltage is read on the meter, current is leaking out of the battery
What factors affect battery life?
improper electrolyte levels, temperature, corrosion, overcharging, undercharge/sulfation, poor mountung and cycling
Where are fuses located?
in a box or panel usually under the dashboard, behind a panel in the foot well or in the engine compartment
Ceramic fuses are available in how many sizes?
in two sizes, code GBF (small) and the more common code GBC (large)
At the end of doing a conductance test, what will the tester display?
indicate the battery is good, needs to be recharged and tested again, has failed, or will fail shortly, or a code that will need to be looked up in the operating manual before taking any further action
When doing a hydrometer test, more variance than 0.05 is an indication of what?
indication that the battery is bad
In a lead-acid battery, what is lead peroxide (Pb02)?
is a dark brown, crystalline material that is found in the grid of the positive plate
What is a element?
is a group of positive and negative plates
In a lead-acid battery, what is a grid?
is a lead alloy frame that supports the active material of each plate
What is the most common cause of parasitic draw?
is a light that is not turning off- such as the glove box, trunk, or engine compartment light
What is electrolyte?
is a solution of sulfuric acid and water
What is watt-hour rating and how is it calculated?
is determined at 0 F because the batter's capacity changes with temperature. calculated by multiplying a battery's AH rating by the battery's voltage
What is reserve capacity (RC) rating?
is determined by the length of time, in minutes, that a fully charged starting battery at 80 F can be discharged at 25 amps before battery voltage drops below 10.5 volts
How is the current rating determined on blade fuses?
is indicated by the color of the plastic case and is usually marked on the top.
How is impedance measured?
is measured in ohm's
Is a parasitic load normal?
is normal unless it exceeds specifications
How does a NTC thermistor work?
is one in which the resistance decreases with an increase in temperature. Always opposite
How does a PTC thermistor work?
is one in which the resistance increases with an increase in temperature. Always the same
What is cranking amp (CA)?
is similar to CCA and is a measure of the current a battery can deliver at 32 F for 30 seconds and maintain voltage at a predetermined level.
What is Ampere-Hour (AH) rating?
is the amount of steady current that a fully charged battery can supply for 20 hours at 80 F without the cell's voltage dropping below a predetermined level.
What is cold cranking amps (CCA)and how is it determined?
is the common method of rating most automotive starting batteries. Is determined by the load, in amps, that a battery is able to deliver for 30 seconds at 0 F without it's voltage dropping below a predetermined level
What is electromotive force (EMF)?
is the force needed to move the electrons between atoms. Is the pressure that exists between the positive and negative point within an electrical circuit
The is "peek-to-peek"?
is the movement of the AC from its peak at the positive side of the graph to the negative side and then back to the positive peak
How is voltage drop in AC circuit's determined?
is the product of the current and the impedance (Z) of the circuit or load. Expressed as E=I x Z
What is open circuit voltage?
is the voltage measured across the battery when there is no load on the battery
What is specific gravity?
is the weight of a given volume of any liquid divided by the weight of an equal volume of water
A batteries chemical reaction creates what and what does it cause?
it creates an electrical imbalance causing the electrons to flow through the path provided by a wire.
If the battery drains quickly and has passed all other tests, what must be done and what results would this provide?
it may be necessary to monitor the drain overnight. Doing this will verify any problems related to the wake-up modes in the various systems
What can be used to check a relay?
jumper wire, voltmeter, ohmmeter or testlight
What is the most common type of battery?
lead-Acid
A battery load test can be called what?
load or capacity test
The larger the wire's diameter, the ___ the resistance.
lower
What must you do prior to testing a battery?
make sure the battery is fully charged and remove the surface charge,
What is a resistor wire?
manufacturers use this special wire to limit current flow and voltage in a circuit. Looks like a normal wire but is not a good conductor and is marked as a resistor
How can a parasitic draw also be in the electronic system?
many of these systems are designed to periodically monitor conditions; these episodes are called wake-up times. If a electronic system wakes up but does not shut down soon afterwards, it is malfunctioning and will drain the battery
What is a conductor?
materials that have low resistance to current flow, 4 or less electrons in the valance shell
What type of blade fuse is most commonly used?
minifuse
What are some examples of conductors?
most metals, such as copper, silver and aluminum
How can you produce electricity?
moving a wire (conductor) through an already existing magnetic field (such as a permanent magnet)
How does a potentiometer work?
moving the control moves the sliding contact away from one end of the resistance but toward the other end.
How does a rheostat work?
moving the control moves the sliding contact away from or toward the fixed end cap, increasing or decreasing the resistance
What is MPMT?
multiple-pole, multiple- throw switch
What are the two basic types of thermistors?
negative temperature coefficient (NTC) and positive temperature coefficient (PTC)
On a relay what is pin 87A?
normally closed
On a relay what is pin 87?
normally open
What instrument is used to measure resistance?
ohmmeter
What test can be used as a substitute for the hydrometer specific gravity test on maintenance-free sealed batteries with no built-in hydrometer?
open circuit voltage test
What are chassis ground connections?
other parts that have a separate ground wire that connects the body of the part to the frame, engine or transmission
What is a capacitance or conductance test?
performed on batteries, describes a battery's ability to conduct current. It is a measurement of the plate surface available in a battery for chemical reaction
What are the three basic types of blade fuses?
standard blade, minifuse and the maxi fuse
Measuring conductance on a battery provides what?
provides a reliable indication of a battery's condition and is correlated to battery capacity.
What is a parallel circuit?
provides two or more different paths for the current to flow through
The rapid opening and closing of the contacts in the voltage limiter produces what?
pulsating voltage at the output terminal averaging about 5 volts.
In a switch what does the pole refer to?
refers to the number of input circuits made by the switch
In a switch what does the throw refer to?
refers to the number of output circuits
What is a voltage limiter?
restricts voltages to the gauges to a particular amount.
What are two examples of variable resistors?
rheostats and potentiometers
How are cells in a battery connected electrically?
series, parallel or both
When doing a hydrometer test, what must the hydrometer readings be between all the cells?
should not vary more than 0.05 difference between cells
On a graph what does the sine wave show?
shows AC changing in amplitude (strength) and direction
On a graph what would AC current look like?
sine wave
What does it mean when doing a hydrometer test on a battery if the float sinks deeply or high in the electrolyte?
sinks deeply--- the specific gravity is low floats high---- the specific gravity is high
What are the two basic types of wires?
solid and standard wires
How can you determine the state of charge and capacity of a battery?
specific gravity tests, visual inspection of battery with a built-in hydrometer, open circuit voltage tests and the capacity test
Where is the current rating on a ceramic fuse?
stamped on the end cap
What is SOC?
state-of-charge
What kind of voltage does a battery store and when does it release it?
stores DC voltage and releases it when it is connected to a circuit
The vehicles charging system continuously restores the battery's?
supply of electrons
When measuring voltage drop, what does that tell you?
tells how much energy is being consumed by the load
What can affect the specific gravity of a substance?
temperature
What is the electron theory?
that current flows from negative to positive
What is the conventional theory?
that current flows from positive to negative.
What is the hole-flow theory?
that something is moving in both directions
What does the "peek-to-peek" value represent?
the amount of voltage available at a point
During each complete cycle of AC, there are always ____ maximum or peak values, ___ for the positive half-cycle and the other for the negative half-cycle.
two, one
What is the primary source for electrical power in all automobiles?
the battery
What would happen to the battery if the vehicles charging system did not continuously restore the battery supply of electrons?
the battery would run out of electrons or all the protons are matched with an electron making the battery weak
How does the cycling type circuit breaker operate?
the bimetal arm begins to cool once the current to it is stopped. Once it returns to its original shape , the contacts are closed and the power is restored. If the current is still to high, the cycle of breaking the circuit is repeated
When the control switch in a relay is closed is the winding energized or de-energized?
the coil is energized
What can control switches?
the driver or can be self-operating through a condition of the circuit, the vehicle or the environment
In alternating current, how does current flow?
the electrons change direction at a fixed rate
In direct current, how does current flow?
the electrons flow in one direction only
What has made electrical grounding more difficult?
the increased use of plastics and other nonmetallic materials in body panels and engine parts
On a graph what would DC current look like?
the line will be flat, which represents a constant voltage
In a lead-acid battery, what is sponge lead (Pb)?
the material pasted onto the grids of the negative plates
The more positive one side of the circuit is, the more?
the more voltage is present in that circuit
If two loads have the same available voltage, the load with the lowest resistance will use___ power.
the most
Batteries have two terminals, a positive and negative terminal, which is inlet and the outlet?
the negative terminal is the outlet for the electrons and the positive terminal is the inlet for the electrons to get to the protons
As a battery ages what happens to the plate surface and what does it cause to happen?
the plate surface can sulfate or shed active material, which will lower its capacity and conductance
How are the cells in a battery in parallel connection connected?
the positive terminals are connected connected together and all the negative terminals are connected to each other
What is induction?
the process of producing electricity through magnetism
The amount of current that flows in a circuit is determined by?
the resistance in that circuit
If the length of a wire is increased what happens to the wires resistance?
the resistance is increased
The amount of electricity produced depends on a number of things?
the strength of the magnetic field, the number of wires that are passed by the magnetic field and the speed at which the magnetic field moves past the wires
In series circuit what is the voltage law?
the sum of all voltages drops must equal the source voltage
How does a conductance tester measure a battery?
the tester creates a small signal that is sent through the battery and then measures a portion of AC current response.
In a series circuit what is the resistance law?
the total amount of resistance in the circuit is equal to the sum of all the individual resistors.
In a parallel circuit what is the voltage law?
the voltage applied to each leg of the circuit will be dropped across the legs if there are no loads in series with the parallel circuit
What is a ground wire or lead?
the wire that serves as the contact to the chassis
What are some examples of insulators?
thermal plastics
What are insulators?
they resist the flow of current, 5 or more electrons in the valance shell
What two things do switches do?
they turn the circuit on or off or they direct the flow of current in a circuit
Why do major components, such as the engine's block and transmission case, also have a grounding wire connected to the frame?
this provides a ground circuit for parts that are mounted directly to the block or transmission.
What is one watt equal to?
to 1 volt multiplied by 1 ampere
What is the purpose of having a set of negative plates in a battery?
to balance the charge
Cells in a battery connected in parallel provide what?
to increase the amperage of the pack of cells
In a parallel circuit what is the resistance law?
total circuit resistance is always lower than the resistance of the leg with the lowest total resistance
How do you remove the surface charge on a battery?
turning on the headlights with the engine off for at least 3 minutes
When the control switch in a relay is closed, making the winding energized, what does it do to the iron core, the armature and the power circuit contacts?
turns the soft iron core into an electromagnet that then draws the armature down which then closes the power circuit contacts connecting power to the load circuit
What is a cartridge fuse and how is it constructed?
type of circuit protection device, is found on most older domestic cars and a few imports. It is composed of a strip of low temperature melting metal enclosed in a transparent glass or plastic tube
What cars were the ceramic fuses used on and how are they constructed?
used on many European imports and the core is a ceramic insulator with a conductive metal strip along one side
What are fixed resistors used for?
used to decrease the amount of voltage applied to a component, such as a ignition coil
What can conductance be used for?
used to detect cell defects,shorts,normal aging and open circuits, which can cause the battery to fail
What can a VAT be used for?
used to test batteries, starting systems and charging systems
Typically, an automobile uses AC or DC current?
uses DC but some components of the automobile use AC
What does VAT stand for?
volt/ampere tester
AC current constantly changes in what?
voltage and direction
What does a VAT have?
voltmeter, ammeter and a carbon pile
The energy used by a load is measured in what?
volts
What is electromotive force (EMF) measured in?
volts
What are the types of Lead-Acid batteries?
wet cell, get cell, absorbed glass mat (AGM) AND VALVE REGULATED
What is continuity?
when a circuit is complete
When the control switch in a relay is open is there current flowing into the coil and is the windings energized or de-energized?
when open no current flows into the windings so it will be de-energized
What is a closed circuit?
when there is a path that connects the positive and negative terminals of the electrical power source
How can the load or capacity test be performed on a battery?
with the battery either in or out of the vehicle
Can excessive battery drain be measured at another time besides at rest?
yes
Can any number of cells be connected in parallel?
yes as long as each group of parallel cells that are wired in series has the same power output
