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