Electrical System

 

 

 

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The Starting System

 

The "starting system", the heart of the electrical system in your car, begins with the Battery. The key is inserted into the Ignition Switch and then turned to the start position. A small amount of current then passes through the Neutral Safety Switch to a Starter Relay or Starter Selenoid which allows high current to flow through the Battery Cables to the Starter Motor. The starter motor then cranks the engine so that the piston, moving downward, can create a suction that will draw a Fuel/Air mixture into the cylinder, where a spark created by the Ignition System will ignite this mixture. If the Compression in the engine is high enough and all this happens at the right Time, the engine will start.

 

Battery

The automotive battery, also known as a lead-acid storage battery, is an electrochemical device that produces voltage and delivers current. In an automotive battery we can reverse the electrochemical action, thereby recharging the battery, which will then give us many years of service. The purpose of the battery is to supply current to the starter motor, provide current to the ignition system while cranking, to supply additional current when the demand is higher than the alternator can supply and to act as an electrical reservoir.

The automotive battery requires special handling. The electrolyte (water) 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 it should be flushed with a mild solution of baking soda and water immediately and you should see a doctor as soon as possible. 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.

Because batteries emit hydrogen gas while charging, the battery case cannot be completely sealed. Years ago there was a vent cap for each cell and we had to replenish the cells when the electrolyte evaporated. Today's batteries (maintenance free) have small vents on the side of the battery; the gases emitted have to go through baffles to escape. During this process the liquid condenses and drops back to the bottom of the battery. There's need to replenish or add water to the battery.

Today's batteries are rated in cold cranking amps. This represents the current that the battery can produce for 30 seconds at 0 degrees before the battery voltage drops below 7.2 volts. An average battery today will have a CCA (Cold Cranking Amps) of 500. With the many different makes and models of cars available today, batteries will come in many different sizes, but all sizes come in many CCAs. Make sure you get a battery strong enough to operate properly in your car. The length of the warranty is not indicative of the strength of the battery.

Battery cables are large diameter, multistranded wire which carry the high current (250+ amps) necessary to operate the starter motor. Some battery cables will have a smaller wire, soldered to the terminal, which is used to either operate a smaller device or to provide an additional ground. When the smaller cable burns it indicates a high resistance in the heavy cable.

Even maintenance free batteries need periodic inspection and cleaning to insure they stay in good working order. Inspect the battery to see that it is clean and that it is held securely in its carrier. Some corrosion naturally collects around the battery. Electrolyte condensation contains corrosive sulfuric acid, which eats away the metal of battery terminals, cable ends and battery hold down parts. To clean away the corrosion, use a mixture of baking soda and water, and wash all the metal parts around the battery, being careful not to allow any of the mixture to get into the battery (batteries with top cell caps and vents). Rinse with water. Remove the battery cables from the battery (negative cable first), wire brush the inside of the cable end and the battery post. Reinstall the cables (negative end last). Coat all exposed metal parts( paint or grease can be used) so that the sulfuric acid cannot get on the metal.

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Ignition Switch

The ignition switch allows the driver to distribute electrical current to where it is needed. There are generally 5 key switch positions that are used:

  1. Lock- All circuits are open ( no current supplied) and the steering wheel is in the lock position. In some cars, the transmission lever cannot be moved in this position. If the steering wheel is applying pressure to the locking mechanism, the key might be hard to turn. If you do experience this type of condition, try moving the steering wheel to remove the pressure as you turn the key.
  2. Off- All circuits are open, but the steering wheel can be turned and the key cannot be extracted.
  3. Run- All circuits, except the starter circuit, are closed (current is allowed to pass through). Current is supplied to all but the starter circuit.
  4. Start- Power is supplied to the ignition circuit and the starter motor only. That is why the radio stops playing in the start position. This position of the ignition switch is spring loaded so that the starter is not engaged while the engine is running. This position is used momentarily, just to activate the starter.
  5. Accessory- Power is supplied to all but the ignition and starter circuit. This allows you to play the radio, work the power windows, etc. while the engine is not running.

Most ignition switches are mounted on the steering column. Some switches are actually two separate parts;

The lock into which you insert the key. This component also contains the mechanism to lock the steering wheel and shifter.
The switch which contains the actual electrical circuits. It is usually mounted on top of the steering column just behind the dash and is connected to the lock by a linkage or rod.

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Neutral Safety Switch

This switch opens (denies current to) the starter circuit when the transmission is in any gear but Neutral or Park on automatic transmissions. This switch is normally connected to the transmission linkage or directly on the transmission. Most cars utilize this same switch to apply current to the back up lights when the transmission is put in reverse. Standard transmission cars will connect this switch to the clutch pedal so that the starter will not engage unless the clutch pedal is depressed. If you find that you have to move the shifter away from park or neutral to get the car to start, it usually means that this switch needs adjustment. If your car has an automatic parking brake release, the neutral safety switch will control that function also.

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Starter Relay

A relay is a device that allows a small amount of electrical current to control a large amount of current. An automobile starter uses a large amount of current (250+ amps) to start an engine. If we were to allow that much current to go through the ignition switch, we would not only need a very large switch, but all the wires would have to be the size of battery cables (not very practical). A starter relay is installed in series between the battery and the starter. Some cars use a starter solenoid to accomplish the same purpose of allowing a small amount of current from the ignition switch to control a high current flow from the battery to the starter. The starter solenoid in some cases also mechanically engages the starter gear with the engine.

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Battery Cables

Battery cables are large diameter, multistranded wire which carry the high current (250+ amps) necessary to operate the starter motor. Some have a smaller wire soldered to the terminal which is used to either operate a smaller device or to provide an additional ground. When the smaller cable burns, this indicates a high resistance in the heavy cable. Care must be taken to keep the battery cable ends (terminals) clean and tight. Battery cables can be replaced with ones that are slightly larger but never smaller.

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Starter Motor

The starter motor is a powerful electric motor, with a small gear (pinion) attached to the end. When activated, the gear is meshed with a larger gear (ring), which is attached to the engine. The starter motor then spins the engine over so that the piston can draw in a fuel/ air mixture, which is then ignited to start the engine. When the engine starts to spin faster than the starter, a device called an overrunning clutch (bendix drive) automatically disengages the starter gear from the engine gear.

The Charging System

As mentioned earlier, the BATTERY is the heart of the electrical system in the car. Something has to keep feeding the battery, or it will lose it's voltage and fail to work. This job is left to the charging system. The principal part of the charging system is the ALTERNATOR. It generates and delivers electrical power to the battery and the rest of the vehicles electrical system. This current must be maintained at between 13 and 15 volts, this is the job of the VOLTAGE REGULATOR. Amperage output of the alternator is dependent on the state of charge of the battery. The charging system consists of the battery, which provides field current to the alternator, so that it can function. The battery also controls the amperage output of the alternator. The voltage regulator, which controls the voltage output of the alternator. An ammeter or voltage indicator lamp, to inform the driver of the condition of the system.

 

ALTERNATOR

The alternator uses the principle of electromagnetism induction to produce voltage and current. A magnet, called a rotor, is rotated inside a stationary looped conductor, called a stator, to generate a voltage. The strength and polarity of the voltage is dependent on the direction of rotation, the strength of the magnetic field, the number of conductors and the speed of the rotor inside the stator. This type of generator puts out AC voltage, hence an alternator instead of a generator, while an automobile is operated on DC current. To convert the AC voltage into DC voltage a series of diodes are used. A diode is an electrical one way check valve that allows current to flow in one direction only. By allowing current to flow in only one direction, we are able to convert alternating current to direct current. Another big difference between an AC alternator and a DC generator, is that an alternator will put out a large current flow at low speed, while a generator needs high speed to put out high current flow. As mentioned earlier voltage output is dependent on the strength of the magnetic field. The magnetic field is created by applying current to the stator from the voltage regulator.

 

VOLTAGE REGULATOR

The voltage regulator controls the field current applied to the alternator. When there is no current applied to the field, there is no voltage produced from the alternator. When voltage drops below 13.5 the regulator will apply current to the field and the alternator will start charging. When the voltage exceeds 14.5 the regulator will stop supplying voltage to the field and the alternator will stop charging. This is how voltage output from the alternator is regulated. Amperage or current is regulated by the state of charge of the battery. When the battery is weak, the electromotive force (voltage) is not strong enough to hold back the current from the alternator trying to recharge the battery. As the battery reaches a state of full charge, the electromotive force becomes strong enough to oppose the current flow from the alternator, the amperage output from the alternator will drop to 0, while the voltage will remain at 13.5 to 14.5. When more electrical power is used, the electromotive force will reduce and alternator amperage will increase. It is extremely important that when alternator efficiency is checked, both voltage and amperage outputs are checked. Each alternator has a rated amperage output depending on the electrical requirements of the vehicle.

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Electrical Systems                                                                                    

1. The electrical pressure or Electromotive Force (EMF), which forces electrons through the     circuit is called .                
a) Current        b) Resistance    c) Voltage    d) Amperage

2. EMF, or electrical pressure is measured in:
a) Ohms            b) Volts            c) Amperes        d) Newton Meters    

3. The actual amount of flow of electrons through a circuit is called:
a) Current        b) Resistance    c) Voltage    d) Amperage 

4. Flow of electrons is measured in:
a) Ohms            b) Volts            c) Amperes        d) Newton Meters    

5. Resistance to electron flow through a circuit is called: 
a) Current        b) Resistance    c) Voltage    d) Amperage

6.  Resistance to electron flow through a circuit is measured in:
a) Ohms            b) Volts            c) Amperes        d) Newton Meters    

7. What type of circuit is shown below?

wpe1.jpg (6596 bytes) 

a) Incomplete    b) Complete    c) Series    d) Parallel

8. What does symbol "G" mean? 
a) Ground    b) Load    c) Connection     d) Battery

9.. What type of circuit is shown below?

 wpe3.jpg (7804 bytes) 

a) Incomplete    b) Complete    c) Series    d) Parallel

10. Electricity must have a completed ___________ to travel through.
a) Wire    b) Battery    c) Phase    d) Circuit

Batteries

11. When is the battery not used? 
a) When the engine starts            
b) To power the accessories when the engine is not running
c) Driving down the road at 70kph with low electrical load
d) Driving down the road at 20kph with all the accessories running

12. The case made of:
a) rubber or polypropylene        b) styrene
c) steel                                             d) lead and acid

13. To make the entire volume of each plate active, rather than just the surface the lead is made:
a) solid        b) wavy        c) spongy        d) curved    

14. What is the electrolyte made of what?
a) lead and sulphuric acid    b) water and sulphuric acid
c) acid                                        d) water and hydrochloric acid

15. How many volts does one cell produce?
a) 6 volts        b) 12 volts        c) 2.1 volts        d) 12.6 volts

16. How many cells in a "12 volt" battery? 
a) six        b) twelve        c) two        d) twenty four 

17. By definition, any acid has an excess of:
a) protons        b) electrons        c) neutrons     d) saturated fat

18. This excess gives any acid an overall _______ charge.
a) negative        b) positive        c) Visa account       d) neutrino

19. When a battery is connected into an otherwise complete circuit with an open switch, and that switch is then closed, what happens to the electrons that are saturating the negative plate?
a) they move onto the positive plate discharging the battery
b) they get used up
c) they change into protons, move through the circuit, and do work
d) they move through the circuit, and do work.

20. These electrons are replaced by electrons from the: 
a) electrolyte    b) positive plate    c) negative plate    d) circuit 

21. This makes the electrolyte:
a) stronger        b) last longer        c) older        d) weaker

22. This makes the specific gravity of the electrolyte:
a) stay the same    b) lower    c) higher     d) heavier

23. When does this process stop? 
a) when the specific gravity reaches 1.275
b) when the battery is completely charged
c) when the electrolyte is completely saturated with protons
d) when all the electrons are gone from the electrolyte

24. At this point, the battery is said to be:
a) completely charged
b) new
c) completely gone
d) completely discharged

25. Charging voltage for a 12 volt battery is:
a) 12 volts        b) 12.6 volts        c) 14 volts        d) 16 volts

26. Specific gravity is a comparison of the weight of any liquid to:
a) pure water        b) sea water        c) battery acid        d) beer and wine

27. What is the specific gravity of pure water? 
a) 1.500        b) 1.300        c) 1.000        d) 0.995

28. What is the specific gravity of a fully charged battery? 
a) 1.500        b) 1.300        c) 1.000        d) 0.995

29. Specific gravity is measured with a ___________________
a) Hydrometer        b) Micrometer        c) battery tool        d) specific gravity meter

30 What happens to the power a battery is able to produce as the temperature gets lower?
a) it increases    b) it stays the same    c) it is zero    d) it decreases

31. How is battery power measured?
a) ohms    b) volts    c) cold cranking amps    d) ampere hours

32. What is a maintenance free battery? 
a) a battery that doesn't normally need to have any water added during it's life
b) a battery that doesn't normally need any maintenance during it's life
c) a battery that never needs replacing
d) a battery that never needs charging

33. The first test for a battery is the visual test. Which is not part of a visual check? 
a) Electrolyte level        b) Terminal condition
c) Specific gravity         d) Case integrity

34. How would you check for a dead cell? 
a) battery voltage is zero        
b) Specific gravity of one cell is much lower than all the rest or the battery measures 10 volts with no load 
c) the battery is discharged
d) the battery puts out no energy

35. What would you say about a battery which had a specific gravity of 1.100 in all cells? 
a) the battery needs to be replaced
b) the battery has a dead cell
c) the battery is shot
d) the battery needs to be charged

36. How would you fix the above battery? 
a) charge it            b) replace it
c) polarize it         d) you can't fix it

37. What would you say about a battery with a specific gravity of 1.275 in five cells, and 1.100 in one cell? 
a) the battery needs to be charged
b) the battery has a dead cell
c) the alternator isn't working
d) there is a loose connection

38. How would you fix the above battery? 
a) polarize it        b) charge it        c) replace the electrolyte    d) replace the battery

39. How does a battery become sulfated? 
a) sitting in a discharged state too long    b) saturated electrolyte
b) water in the electrolyte evaporates        d) 

40. What happens inside a battery to make it sulfated?
a) too much sulphuric acid in the electrolyte.
b) sulphuric acid is gone out of the electrolyte.
c) sulphur coats the plates
d) sulphur coats the terminals

41. What is a carbon pile tester? 
a) same as a hydrometer        b) a load tester
c) tests for piles of carbon     d) measures starter load

42. What would you load a 500 amp battery to during a load test? 
a) 500 amps    b) 250 amps    c) 100 amps    d) 50 amps

43. For how long?
a) 10 minutes    b) 1 minute    c) 15 seconds    d) 5 seconds 

44. The voltage should not go below how many volts?
a) 6.1        b) 9.6        c) 12        d) 14

45. Why should the negative terminal always be disconnected first and re- connected last when working on the battery or starter? 
a) to prevent shorting the battery out        b) to prolong its' life
c) so it works better                                       d) to protect the computer

Charging System

46. What three things are needed to produce electricity? 
a) capacitor, coil and diodes.        b) completed circuit, magnetic field and motion
c) battery, alternator, and starter  d) Ben Franklin, Thomas Edison, and Michael Faraday

47. What is the main disadvantage of a generator? 
a) too heavy                                     b) doesn't last very long    
c) produces too much power        d) doesn't produce power at idle

48. In a generator, which  coil rotates as a part of the armature assembly?
a) output coil        b) voltage regulator coil        c) ignition coil        d) field coil

49. In an alternator, which  coil rotates as a part of the armature assembly?
a) output coil        b) voltage regulator coil        c) ignition coil        d) field coil

50. In a generator, which  coil is stationary as part of the stator assembly?
a) output coil        b) voltage regulator coil        c) ignition coil        d) field coil

51.In an alternator, which  coil is stationary as part of the stator assembly?
a) output coil        b) voltage regulator coil        c) ignition coil        d) field coil

52. In and alternator, what goes through the brushes to the armature assembly?
a) output current    b) field current    c) regulator current    d) black current

53. How is AC current produced at the output coils of an alternator, converted to DC current at the output terminal? 
a) rectifying capacitor    b) rectifying diodes    c) transistors        d) an inverter

54. In both alternators and generators, the voltage regulator controls what to control output?
a) output current    b) field current    c) regulator current    d) black current

    Starters.

55. Whenever electricity travels through a wire, what builds up around that wire.
a) a magnetic field        b) a force field        c) the Klingon cloaking device    d) plaque buildup

56. What do unlike magnetic fields do to one another?
a) repel            b) dislike        c) attract        d) ignore

57.What do like magnetic fields do to one another?
a) repel            b) dislike        c) attract        d) ignore  

58.In an electric motor, torque is caused by the "kicking" action created between the field frame and the armature, caused by what?
a) field frame heat        b) like magnetic fields in the field frame and armature         
c) armature inertia        d) commutator and brush friction

59. The torque is made continuous by what?
a) the field frame                             b) the armature and brushes
c) the commutator and brushes    d) a computer

60. In an electric motor, the opposing magnetic fields are created between the field frame coils and what part?
a) armature coils                b) commutator and brushes
c) armature bearings         d) insulators 

61. What two jobs does the solenoid do?  
a) pushes the pinion into mesh with the ring gear, and completes the circuit to the starter motor.
b) engages the overdrive unit, and honks the horn
c) energizes the field frame unit, and spins the armature.
d) pushes the pinion into mesh with the differential, and engages the starter clutch

62. TRUE or FALSE The starter pinion is already spinning when it meshes with the          ring gear.

63. The one way clutch which acts as a safety device to prevent the ring gear from driving the pinion, is called what?
a) centrifugal clutch        b) bendix        c) over-running clutch        d) starter clutch                   

64. What are two advantages of a reduction gear starter? 
a) lighter and uses less current                 b) simpler and cheaper
c) more torque and more expensive        d)  higher cranking RPM and heavier

Troubleshooting

65. What is the electrical trouble shooting tool called that is simply a wire with alligator clips on each end? 
a) test light        b) continuity tester        c) test lead        d) multi meter        

66. The alligator clip on a test light is normally connected to what?
a) ground            b) 12 volts        c) a computer           d) a wire

67. One tail light is out. What is the most likely cause? 
a) burned out fuse        b) burned out bulb        c) broken wire    d) bad ground

68. Both tail lights are out. What is the most likely cause?
 a) burned out fuse        b) burned out bulb        c) broken wire    d) bad ground

69. One tail light is out, there is power at the socket and a new bulb doesn't work. What is the most likely cause?
a) burned out fuse        b) burned out bulb        c) broken wire    d) bad ground

70. Which is not a protection device?
a) fuse        b) switch        c) fusible link        d) circuit breaker

71. Which in not a control device?
a) switch        b) flux capacitor        c) relay        d) variable resistor

72. Where is the fuse panel usually located? 
a) under the dash on the driver's side        b) under the dash on the passenger side
c) behind the passenger side kick panel    d) in the trunk

73. One headlight is out on low beam, but both work on high beam. What is the most likely cause?  
a) a bad ground            b) a faulty circuit breaker or switch
c) a broken wire            d) one filament of a dual filament bulb is burned out

74. One headlight is dimmer than the other. What is the most likely cause?
a) a bad ground            b) a faulty circuit breaker or switch
c) a broken wire            d) one filament of a dual filament bulb is burned out

75. The headlights stay on for a while, and then go off; stay off for a while, then come back on.
a) a bad ground            b) a faulty circuit breaker or switch
c) a broken wire            d) one filament of a dual filament bulb is burned out

76. One headlight is out, a new bulb doesn't work, and there is no power at the socket. What is the most likely cause?
a) a bad ground            b) a faulty circuit breaker or switch
c) a broken wire            d) one filament of a dual filament bulb is burned out

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