Starter motor's

Starter motor bench testing and repair.

In this exercise we first have to do a no load bench test to determine that the starter motor is working before we begin. The starter that we used for this no load test resulted in a voltage of 11.20v the minimum specification for voltage is no less than 11v, the current of this starter on the no load test is 56.1Amps the specifications for this test is 30-50Amps the result is just slightly out of the range but acceptable.

Next we proceed to disassemble the starter motor, after disassembling the starter we visually inspect the armature first for overheating; there appears to be no overheating.

Next we check the armature for signs of burning; there appears to be no burning on the armature.

Then we inspect the armature for signs of physical damage; there appears to be no sign of any physical damage on the armature.

finally we check for polling; there is no visual sign of unnatural polling on this armature, this concludes that visually the armature appears to be in good condition.

We then test for a ground circuit on the armature, we receive a infinity reading from the armature which is the specification.

Now we test for continuity circuit the specification for this is between 0 and 1 Ohms we recorded 0.7Ohms which is within the specification.

The next test is measuring the diameter of the commutator the minimum diameter is between 26.8mm and 31mm, we recorded a result of 30mm which is within the specifications,

the mica undercut specifications is between 0.7mm and 1mm we recorded a 0.7mm result which passes the mica under cut.

Next we tested the armature shaft for run-out to do this we place the armature between 2 "V" blocks then turn it 360 degrees while reading the dial test indicator set up on the armature core.

The specifications for this are 0.0mm to 0.2mm we recorded a result of 0.1mm which is within the specifications.

the alternate method for testing the armature for continuity and ground circuit is to use a 48volt test light.

To do the continuity test you keep one of the probes on 1 segment and move the other probe around each of the segments, the test light should glow in this test to indicate a pass result.

For the ground test you place one probe on any commutator segment and the other on either the armature core or shaft for a pass result the light should NOT  glow.

Our armature recorded the result of a pass for both tests.

Next is an internal short circuit test, for this we first place our armature on the "V" of the growler then we turn the switch on to the growler position, now we hold a hacksaw blade along the armature and rotate the armature, the hacksaw blade didn't vibrate when the armature was rotated indicating that there is no short circuit.

Next we do visual checks on the field coils and pole shoes, first we check for signs of overheating; there are no signs of overheating on the field coils or pole shoes.

Next we check for signs of burning; we determine that there are no signs visually of any burning on the pole shoes or field coils.

Then we check for signs of physical damage; on our field coils  and pole shoes there is no sign of physical damage.

Lastly we check for signs of poling; there does not visually appear to be any sign of unnatural poling on our pole shoes or field coils.

Next we test the field coils for continuity for this test the specifications are between 0 to 0.02 Ohms. we recorded a result of 0.02 Ohms which is within the specifications.

Next we test the field coils for grounding the specification for this is an infinity result, when we tested our field coils we recorded an infinity result.

Now we test the brushes of the starter motor the specifications for this are a minimum length of 5mm for our brushes we recorded; brush 1 at 15mm, brush 2 at 20mm and brush 3 at 14mm.

Then we test the brush holder assembly, for this test  the specifications are infinity upon testing we recorded an infinity result.

This is a pull in winding test for this we we connect a 9v power supply between the ignition and starter motor  supply, the specifications for this test are between 8-12Amps we recorded a reading of 12Amps and witnessed a pull-in action from the plunger.

Next we do a hold in test the specifications for this are 5-8Amps on this test we recorded a result of 8Amps and witnessed the plunger remaining in until the power is disconnected.

Now we visually inspect the pinion gear, bushes and the clutch. to do this with the pinion gear we check it for damage and smooth movement along the armature shaft, there appears to be no damage to the pinion gear and the movement is smooth giving us a pass result. Next we check the bushes by inserting the end of the armature shaft into the end housing and check for bush clearance, the bushes have clearance and no sign of physical damage giving a pass result. Finally we check the clutch to do this we turn the pinion gear  in the direction of the motor rotation, the clutch was free wheeling wich indicates it is working correctly.

After re-assembling the starter motor we test it again for a final no-load test, the voltage specifications are no less than 11 volts, we recorded a result of 11.70v for the no-load test the specifications for the current should be between 30-50Amps we recorded a result of 54.1Amps which is just slightly out of the range but acceptable.

We used a mitsubishi starter motor. Model number 30281 for these test.

Batteries

In this exercise we are inspecting batteries;
we are testing a conventional lucas battery with a 400 CCA rating
Battery number 128HD
we did an electrolyte test using a hydrometer.

The battery showed no signs of swelling (swelling is caused by over charging of the battery).

For safety in this exercise  we should not that the nearest sink in the room is on the far side of the room from the door and that safety glasses are to be worn during this exercise.

apon testing the electrolytes we attained the following results

Cell 1: High reading

Cell 2: High reading

Cell 3: High reading

Cell 4: High reading

Cell 5: High reading

Cell 6: High reading

The O.C.V was 6.60v on a 20v scale, which results in the battery being less than 25% charged

as the battery needs to be atleast 50% charged we have to charge our battery before any more tests can be done so we put our battery on the battery charger.

The voltage of a 50% charged battery is 12.4v, After charging the battery we did an electrolyte specific gravity test on it the hydrometer test gave the readings:

Cell 1: 1.250

Cell 2: 1.250

Cell 3: 1.225

Cell 4: 1.210

Cell 5: 1.250

Cell 6: 1.250

The gravity variation of this battery is 0.04.

The allowable variation is 0.25-0.50, this concludes that our battery cell variation was a pass result.

Next is a battery load test, for this test the battery needs to be atleast 50% charged(12.4OCV)
In this exercise the battery we are using is a conventional lucas battery with a CCA rating of 310.
We are going to apply a load of 155Amps(Half the CCA rating), the voltage held must be atleast 9.6v at 155Amps we will apply the load for a maximum of 15 seconds.
After applying the load of 155Amps for around 15 seconds the voltage held on this battery was 10.6v which was a pass result.

The next test we did was a digital battery test this time we are using a lucas conventional battery model number: NS40210 with a CCA of 310, we saw the "SAE" letters flash across the screen we changed the CCA rating to suit the battery, the CCA rating was successfully changed,
upon testing the digital meter read as a fail for the test this was due to possibly corroded terminal connections or corroded terminals, the OCV on this battery was 12.87v the CCA calculated from the digital meter was 225CCA when comparing to the column provided it indicates that the battery is over-charged.
given the condition of the battery it is advisable that it is replaced as well as the terminal clamps being cleaned with a soda/water solution.

Logic probe

We have self-constructed a logic probe using:
1x Red L.E.D
1xGREEN L.E.D
1x Black wire(2 meters in length)
1x Red wire(2 meters in length)
2x 1K resistors
1x Red alligator clip
1x Black alligator clip
1x 100mm plastic 7mm diameter
Shrink tubing
1x Black 2.4mm diameter 300mm long
1x Red 6.4mm diameter 175mm long
1x Black 12.7mm diameter 125mm long
1x Brass rod 150mm long

Construction:
1st we soldered the 1K resistors and wires together then we soldered the L.E.D's to the resistors of the positive and earth wires respectively.
Next we put the heat shrink over both the wires up to the L.E.D's and proceeded to use the heat gun to shrink the material around the wires.
Next we have to solder the L.E.D's to the brass rod, then we machine the end of the brass rod to a pen like tip.
After that we put heat shrinks over both ends of the brass rod leaving the pen like tip exposed and L.E.D's visible and apply the heat gun.
next we cut a groove out of the plastoc tube approx 5-10mm long and then we put the plastic tube over both wires and position it just behind the L.E.D's then put a large heat shrink over the plastic tube and then apply the heat gun proceed to do the same to the other end still leaving the pen like tip exposed.
Next we solder the alligator clips to the respective wires for positive and earth wires.

To Test:
Attach to a power supply no more than 24v DC
Then touch against positive and negative terminal, the red L.E.D should light up on the positive terminal and the green L.E.D should light up on the earth wire.

The Logic Probe uses a series circuit with 2 one way diodes one allowing flow to the positive and the other allowing flow to the earth

Alternators

OFF CAR ALTERNATOR EXERCISE

In this exercise we disasembled a alternator that was off a toyota camry. We then performed tests on the various components of the alternator, the first test was to check if there was a circuit through the slip ring this was done using a digital multimeter the result of the reading was infinity. The next test was to find the internal resistance this was done using a multimeter the specifications for results was anywhere between 2-6 Ohms we got a reading of 2.8 Ohms on our slipring our tests conclude that the slip ring is operating correctly.
The next component tested in the alternator is the stator, the stator is measured from the common(the point which has the most wires connected) the stator was tested for resistance

from point A to D the resistance was 0.2 Ohms which is within the specification range of 0 Ohms to 0.2 Ohms from point A to C the resistance was 0.1 Ohms also within the specification range
from point A to B the resistance was 0.0 Ohms
the final test on the stator was from the common to the earth to test for a circuit the result was an infinity reading meaning there is no circuit.
The stator's purpose is to act as the conducter in the alternator when the car is running .

The next component tested was the rectifier, it was tested for voltage drop on the positive diode first
the specifications where between 0.5-0.7VD
at point 1 the reading was 0.512VD
at point 2 the reading was 0.486VD
at point 3 the reading was 0.500VD
on this test point 2 failed to meet the specifications.
The next test was a positive diode test, all 4 points measured as infinity which was the specifications.

The negative diode test with the negative lead on earth measured as infinity which was the specification as seen below:

The next test was the voltage drop for the negative diode
at point 1 the reading was 0.518VD
at point 2 the reading was 0.513VD
at point 3 the reading was 0.527VD
on this test there where no points that failed.
The purpose of the rectifier is to turn alternating current to direct current for the motor vehicle

The next test was a transpo-regulator test which is desinged to test an alternators regulator.
The spec's for our test are:
part number: IN225
field setting: A
voltage: 12v
set point spec: 14.5v
in the test the short circuit light was off, the warning light was on and stayed on and the field light was flashing continuously the setpoint voltage read as 14.5 which was a pass result.

the purpose of the voltage regulator is to keep the voltage at the required level for the load on the alternator and to stop it producing voltage when it is not needed.

The last test was done on the alternator brushes testing there length both brushes measured at 7.5mm each the specification are at 4mm each so a pass resuly, the point of the brushes is to supplly electricity to the slip rings

ON CAR ALTERNATOR TESTING

In this exercise we performed various tests on an alternator that was still attached to the vehicle,
the first thing we did was a check for saftey things such as is the vehicle in park/neutral?, is the hand break applied?, etc apon checking the engine and charging system i recorded that the mazda 323 engine that i was using  is chain driven, the teeth all have good length on them the chain is properly tensioned and runs across the alternator correctly. We then carried out a "no load" test the OCV was measured at 12.6v the regulator volt spec was 14.5v and the regulator voltage reading was 13.8v, the "no load" ampere output was 9.6 amperes which is withing the specification range for a carburetted engine of between 5 to 12 ampere's.

In the "load" test we used a induction multimeter, we started buy adjusting the RPM to 2,500 we then put a load on the alternator the ampere reading we got was 21.9 ampere's and the charge voltage under load was 12v which was a failed test this is most likely due to the engine having old and tired components.

We performed a voltage drop test on the engine.
The first point was between the battery positive and alternator output while the engine was running, giving a result of 0.13VD the specifications here was a volt drop below 0.20VD.
The second point was between the battery negative and the alternator body while the engine was running, giving a result of 0.16VD the specifications here where also a volt drop below 0.20VD.
the total voltage drop across the engine was 0.29VD the specification was for a total voltage drop below 0.40VD

Overall the engine proved to be in an electrically well kept state

Saftey

Personal protection equipment is the equipment that each individual uses to protect themselves from any possible accident or injury that may occur to themself, this equipmen includes things such as overalls, steelcap boots, saftey glasses and gloves. In auto-electrical work the biggest danger is electricution, this can be avoided by making sure that the ignition is off when doing electrical work on it and also making sure that all mains for power are correctly earthed and contain a circuit breaker.

Circuits

There are three types of  circuits; circuits in series, circuits in parallel and combined circuits.

Series and parallel circuits respectively are known as individual circuits, where as a combined circuit is one in which there are one or multiple series and parallel components to the circuit as a whole.

In a series circuit that has a twelve volt supply the components are all runing off the one voltage so as the current flows through the circuit and across the components the voltage of the components drop for example if you have two light bulbs in a series circuit such as this one:

The light bulbs or components both use six of the twelve volts availible to the total circuit, this is because there is less current due to more resistance in the circuit. When compared to a single bulb in series causes the two bulbs in this circuit to be dimmer.

In a parallel circuit that has a twelve volt supply the components are using the whole twelve volts each so when we look at this three bulb circuit wired in parallel:

We can see that the three bulbs are brighter than the bulbs in series this is because the bulbs are each drawing the maximum availible voltage from the supply although they are still limited by there individual wattage of the bulbs, in a parallel circuit the components draw a consistant amount of current which is higher than that of the series circuit due to less resistance.

In a combined circuit we have series and parallel components to the whole circuit respectively.Of note in the combined circuit when calculations are needed you are to work out the total resistance of the parallel component of the circuit first. with ths kind of circuit there is a share of voltage between the components of the combined circuit, in this type of circuit if we have a twelve volt circuit with two bulbs in parallel and three more bulbs in series in the whole circuit the bulbs in parallel will use the maximum availible voltage each and the bulbs in series will share the remaining volts between them. An example of this is the double filiment bulbs in brake lights where when driving at night if one of the filiments blows the other will still be lit when the headlights are on but will go out when the brake pedal is applied.