ALTERNATOR FUNCTIONAL TESTING

How does the alternator operates.

Let me first discuss the electro mechanical operation of an alternator using a separate voltage regulator.

An alternator has a winding called the ROTOR, since it is a winding there are two ends , one will received a positive current from battery and the other goes to the ground or body of the car. This rotor rotates within an the center of a winding again called the STATOR.  Some stator windings has three ends, each of this ends goes to the positive side of  a diodes, that means , there are three diodes , of course one side of the diode is grounded. .  There are another three diodes where its negative end is connected to the positive of the previous diode mentioned.  The positive side of these additional diodes is connected to each other or lump into one terminal,  this terminal now goes to the battery  to charge that battery.

When the rotor rotates a magnetism occurred and electricity is produced by the STATOR in each three terminal  but on AC mode, the last three diodes mentioned above rectifies that AC power into DC power , the car battery being DC. 

HOW DOES IT OPERATES.

There is a voltage regulator with two separate windings , each of which has contact points that swings to a two fixed metal  contact .  this regulator has  SIX  terminal wires that goes outside  broken down as ff:

   FIRST WINDING 
     1.  came from a fixed metal  where one side of the movable contact point of one of the winding is temporarily connected.   This wire goes to the fuse box.
      2.  came from another fixed metal which is grounded ,in tandem with the one mentioned in number 1 above. This wire goes to the negative side of the ROTOR winding of ALTERNATOR.
     3.  came from the other end of the resister mentioned in no. 1. that wire goes to the positive side of the ROTOR WINDING
      
SECOND WINDING

     4.  came from a fixed metal which is grounded where one side of the movable contact is temporarily connected.  That wire goes to  a bulb or pilot light to supply that bulb with negative.
      5.  came from the end of a winding , that wire goes to one terminal of the STATOR WINDING  in the alternator.
   6.   came from the a fixed metal in tandem with the one in no. 4, that wire goes to the fuse box also.

INTERNAL WIRING CONNECTION OF THE VOLTAGE REGULATOR
    1. the wire mentioned in number 2 above , is connected to the other end of a FIRST WINDING.
   2. The other end of the first winding goes to the fixed metal mentioned in number 4.
  3. the other end of the secondary winding mentioned in no.5 goes to the fixed metal contact mentioned no. 2.
 -     
 THREE WIRES OF THE voltage regulator is connected to the alternator , ONE to positive side of ROTOR,  SECOND to negative of ROTOR, 3RD, goes to the STATOR WINDING.

 when the ALTERNATOR ROTATES,  the movable contact of the SECOND WINDING transfers to the other side of the fixed metal, it transfers because of the positive current supplied from the AC produced by the STATOR. The bulb looses a negative supply so it becomes dead,     the rotor produces magnetism and the STATOR produces  AC current , passes thru the rectifier diode and out as DC current then goes out to the battery for charging
There will come a time that the battery will be fully charged with high current  carried by the wire from fuse box that goes to the fixed metal of the SECOND WINDING where the positive of the winding of the FIRST WINDING  is connected .
In this instance the movable contact of the FIRST WINDIng transfers to the negative side of the fixed metal contact., in this case the wire that goes to the positive of rotor is converted to negative hence the charging process is cut.  If the battery looses that high current due to usage, that contact point goes back to positive. then the cycle continues..


HOW TO TROUBLE SHOOT THIS CHARGING SYSTEM

IF AN AMPERE GAUGE and  VOLTAGE REGULAR ARE USED.
1.  the ampere gauge  fails to deflect indicative of no charging.

A QUICK CHECK CAN BE USED AS FOLLOWS:

1.  run the engine, , get a short wire, insert that wire on the center of the six terminal socket located on the side of the plastic socket has a notch or curved side.
2. scratch the other end of the wire to a good ground, if with spark, meaning, your rotor winding is ok. if no spark , your rotor  winding is cut open or sorted.
3. if  with SPARK,, diode, or loose connection of the three terminal ends of the STATOR is open.
4. remove the single wire connected to the rear end of the alternator, START THE ENGINE, get a piece of wire, connect the wire end to the rear end nut of the alternator, and the other end, scratch to a good ground, if no spark , then DIODE is dead or STATOR winding is burned or loosely connected.


    How to trouble shoot.  CHECK FIRST IF THE ALTERNATOR BELT IS CUT OR SLIDING.
1.  remove the nut in the alternator where the wire that goes to the ampere gauge, or to the fuse , or to ignition switch, or to positive battery  is connected. Remove also the wire in it. Start the engine, get a one foot wire, connect to the NUT mentioned  then scratched the other end to a good ground ,  there must be a  spark , IF SO, your alternator is producing electricity , of no spark,  so  maybe the wire you just remove is cut open, or your ampere gauge is defective.....NO SPARK. then maybe the stator not producing current. .
2.  remove the voltage regulator,  at its back , using the six terminal socket , locate the wire that comes from the rear end of alternator MARK  N , (neutral), start the engine, using the one foot wire, insert that wire to the terminal of the N  and one end scratch to a ground,  there must be spark,  If so, your ROTOR IS OK,  if no spark, maybe the ROTOR winding is open or shorted or some loose connection on STATOR  WINDING.  
3. RUN the engine ,   while the voltage regular is removed , locate at the back,  the wire that came from the end of the resistor that goes to the ALTERNATOR   MARK   F.  Using that short wire, insert it on the six terminal socket for F , scratch it to a ground , NO SPARK , maybe the fuse is busted, or the wire on the six terminal socket got loose.
4. check for fuse busted or loose connection on the six terminal socket,,,, if  fuse is busted then replace it and run the engine again. , if still not charging.
5. go back to no. 2 above, if  still NO SPARK  then the ROTOR WINDING IS OPEN OR SHORTED, replaced  it.
6 if in no. 4, the fuse is OK , then disassemble the alternator and check if STATOR WINDING is burned or it has loose terninals.  if all OK., then
7. check all diode for an OPEN terminal.
   

    IF A PILOT LIGHT IS USED AND A ELECTRONIC VOLTAGE REGULATOR IS USED.

The pilot light stay lighted.
 1.  Check if alternator belt is cut or sliding., if not.
 2.  while engine is running , open any lights,  remove one terminal of the battery cable,  if the engine still runs, and light stays lighted ,that means the alternator is still producing current to supply the battery .   In this case the engine gets electric power from the alternator.  There is only  something wrong with the wiring of the pilot lamp.

IF YOUR BATTERY IS PRESUMED WORKING WELL AND YET THE ENGINE DOES NOT CRANK FASTER (  after using it )  BUT WHILE USING A FUULY CHARGED BATTERY , THE ENGINE STARTS THEN SOMETHING IS WRONG WITH THE ALTERNATOR.

1. Get a voltmeter,  set it to 50Volts DC.
2. Get a good battery, Start the engine .
3. Open the headlights, the aircon, Measure the voltage being produced by the battery using the voltmeter
4.  If the reading falls below 12, your alternator is defective. The reading should be at least 13 and above.