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?Alternators 101?
I will attempt to take a layman thru a quick synopsis of alternator theory, as there has been much discussion on the message board about this subject matter.
When an electric current is passed through a conductor, a magnetic field is generated around that conductor. The reverse is also true, in which a conductor which moves across a magnetic field develops a voltage.
Current will flow if a complete electrical path is provided.
This is the principle of ElectroMagnetic Induction (EMI), and is one method of inducing a voltage in a wire that is either cutting or being cut by a magnetic field.
To further illustrate this physics principal, imagine two bar magnets placed end to end, the North Pole on one magnet facing the South Pole on the other magnet. You now have a magnetic field that is present in the space between the magnets.
Passing a length of wire through this space will create a voltage. This is termed an induced voltage.
How much induced voltage is dependent on the length of the wire that is passing thru the magnetic field, and how fast that wire is passed through that magnetic field.
The wire moving through the field can have different shapes. It might be a straight wire, or perhaps a coil or loop of wire, or even loops of wire. The longer the wire passing through the magnetic field, the greater the voltage induced on that wire.
An increase in the magnetic field produces an increase in the induced voltage. Also, the greater the speed at which the wire moves thru the magnetic field, the greater the voltage.
It doesn?t much matter if you move the wire or move the magnetic field, both activities will generate a voltage. If the magnetic field is increased, an increased voltage will be induced, if the magnetic field is reduced, a reduced voltage will be induced.
This is because of the magnetic fields physical properties, they have lines of magnetic force that flow from the North Pole to the South Pole.
The magnetic field that is developed and surrounds a current-carrying conductor can be visualized as spreading in a radial pattern outward from the conductor. Much like ripples of water when a stone is dropped into water.
Now, just as in magnets, like charges repel each other, and unlike charges attract each other.
Those magnetic lines repel each other, the stronger ones are the ones nearest the magnetic poles, since they repel other lines of magnetic force, other lines are moved further away, and so on and so forth.
So, getting back to how all of this works, we find that we can manipulate the speed, the distance, or the magnetic field strength applied, in order to manipulate the induced voltage.
If we increase the magnetic field, then the conductor cuts through more lines of force for a given distance traveled. A stronger magnetic field has its lines of magnetic force more tightly bound. Increasing the number of lines of magnetic force that are cut in a given distance and time, increases the induced voltage.
The laws of physics also indicate that changing the angle of the conductor that is passed through a magnetic field will influence the induced voltage.
A 90-degree angle has been shown to create the greatest induced voltage. By 90-degrees, we are referring to perpendicular, like a knife slicing a bread loaf. The further one deviates from this 90-degree angle, the smaller the induced voltage. This is similar to slicing that loaf of bread, if we cut it at an angle, the knife has to travel longer to cut thru the same vertical distance of the loaf, and transferring this ?bad analogy? to the alternator, magnetic lines of force can be cut at 90 degrees, and thus travel a shorter distance in a given period of time. Thus they cut more magnetic lines of flux, thus generating increased voltages.
Another interesting physics property to note is that if we pass the conductor back and forth thru the magnetic field, the voltages that are induced will be of opposite polarities from each other.
One direction thru a magnetic field will induce a positive voltage, and reversing that same conductor (the opposite way) thru the magnetic field produces an induced voltage that is of the opposite polarity. Even though there is no change in the conductor, or the magnetic field, only in the direction of travel.
So, moving a conductor back and forth thru a magnetic field causes voltage to be induced and the voltages will be of opposite polarities of each other.
In review of these basics, we can state the following?
The greater the speed of a conductor that is moving thru a magnetic field, the greater the induced voltage.
The longer the conductor, the greater the induced voltage.
The denser the magnetic field, the greater the induced voltage.
The closer to 90 degrees that the conductor cuts across the magnetic lines, the greater the voltage.
Another way to put all this is to simply state that:
The induced voltage is directly proportional to the rate of speed of the conductor cutting through the magnetic lines of force, all other things being equal.
In this sense, the rate of speed can also be tied to the number of magnetic lines of force that the conductor passes thru in a given time frame. Increasing the speed or length of the conductor or magnetic field strength will all result in increasing the induced voltage.
The same can be said of the opposite, reduce any of the properties mentioned, and the induced voltage will be reduced in direct proportion.
If the conductor that the magnetic field is passing through is part of an electronic circuit, then current will flow in proportion to the induced voltage. The induced voltage creates the current flow, and if you can find a way to prevent the voltage from rising, then the current has to increase, limit the current and the voltage needs to rise.
An alternator has a coil of wire wound around a Ferro-resonate material. In this manner, an electro magnet is created, because voltage is applied to this coil, current flows thru it, and they create a magnetic field. This magnetic field is polarized, which simply means that it has a North Pole and a South Pole.
When a current-carrying wire is wound into a number of loops to form a coil, the resulting magnetic field is the sum of all of the single loop magnetic fields added together. Increase the loops making up the coil, and you increase the magnetic field.
In review, the rotor of an alternator has an iron core, which is called an armature. This rotor or armature has copper wire wrapped around it. Passing 12Vdc to this coil of wire, results in current flow, which in turn produces a magnetic field and magnetizes the iron core, thus making the field (magnetic) denser. The rotor is heavy and is supported in the alternator housing via front and rear bearings that support a shaft, outside the alternator, a pulley is mounted on this shaft, to engage the alternator belt, which is driven by the pulley on the crankshaft.
So, now we have a dense magnetic field and as the engine speed of the vehicle increases, we can see how the density of that magnetic field increases.
Here is a hint?want to know if the Brushes on the alternator need replacing, put a screwdriver against the alternator, being careful not to get it hung up on anything, and check out the magnetism that the alternator puts out. With time, you can ?feel? the difference in magnetism intensity, and judge ?good? brushes and ?bad? brushes.
The stator of the alternator is made up of three loops or coils of wire that are mounted to the housing of the alternator, which are stationary. The rotating magnetic field whirls through these coils of wires inducing a voltage. Now, since this rotating mass is changing the angles of the field strength (magnetic field) as it rotates, the induced voltage and the current that these stator loops carry vary accordingly.
Each stator loop coil creates a 360-degree voltage that is known as a sine wave. The induced voltage gradually increase until the angle is at 90 degrees (peak inducement), and as the angles decrease again, the voltage decrease correspondingly; until the magnetic field begins to approach another set of stator loops or coils of wire, and the process starts all over for that particular loop coil.
In our alternator example, we have three loops of wire, and these three loops are placed such that a sine wave in each loop is generated. A complete revolution of the rotor assembly, which is 360 degrees of revolution, gives us three overlapping voltages that are 120 degrees apart (360 divided by 3 equals 120). The configuration of the windings causes these Alternating Current (AC) sine waves to overlap each other,
Once the AC voltages are created, we need to modify them because our Jeeps run on 12Vdc. The battery is responsible for supplying power to the electrical loads, and the alternator is responsible for keeping the charge rate of the battery within design limits.
These overlapping sine waves have their negative going voltages chopped off by diodes, and thus we end up with a series positive humps of DC voltage.
Electronic components in the regulator circuit smooth out this voltage, in order to generate the 13.5Vdc to 14.5Ddc, required by the battery for topping off its charge.
We are generating the AC voltage needed, in order to rectify or alter it, to produce a voltage that is sufficient to charge a battery.
The alternator is a three-phase generator with a built-in rectifier circuit consisting of six diodes in a full-wave bridge rectifier circuit.
In essence the diodes are solid-state switches with no moving parts, making them maintenance-free.
When they fail, they usually short.
When the rectified DC from each of the three-phase windings is added together or superimposed upon each other, the positive peaks overlap to produce a much cleaner DC with much less ripple.
Lead-acid auto batteries last longer when charged with pure DC than high ripple rectified DC. Three-phase windings were designed into alternators to produce DC of great purity.
As the pulley is rotated by a belt, (connected to the automobile engine's crankshaft), the rotor is spun past a stationary set of three-phase windings that make up the stator.
Recall that changing the magnetic field will change the induced voltage. Automotive engineers take advantage of this fact by altering the field strength of the alternator (rotor assembly) in order to correspondingly change the output of the alternators DC voltage.
Speaking of the rotor, you may be wondering how in the heck do we get reliable electrical connection to a rotating assembly?
The engineering folks used a clever set of copper "rings" incorporated into the shaft of the rotor assembly. Stationary ?carbon brushes" are held in firm contact with these ?slip rings? by spring pressure. This supplies the voltage required by the rotor assembly to create the magnetic field.
Many modern alternators are equipped with built-in "regulator" circuits that automatically switch battery power on and off to the rotor coil to regulate output voltage.
It is the regulators that control all of this rectifying and modulation of the field strength, in modern day alternators. Some regulators are designed so that the field strength is such that it will not produce an output in the stator windings until a minimal threshold level is overcome.
That is why some vehicles need to have the engines revved, so the alternator ?kicks in?.
If you lend that vehicle to a very soft-footed individual, it is conceivable that they will not exceed this threshold in the daily driving and you will be chasing your tail around trying to diagnose a phantom problem.
The operator is at ?fault? here, and needs to get up on the freeway once and awhile.
This seldom happens, but stranger things have happened.
Some of the alternators used are the Delcotron 10-SI with 3 cooling vents
0 amps at 1200 alternator rpm
23 amps at 1600 alternator rpm
60 amps at 5000 alternator rpm
Some of the alternators used are the Delcotron 12-SI with 6 cooling vents
0 amps at 1600 alternator rpm
30 amps at 2000 alternator rpm
70 amps at 6000 alternator rpm
The CS-130 105 amp Delco alternator
50 amps at 1600 alternator rpm
100 amps at 4000 alternator rpm
The SI moniker stands for System Integral or internal regulation.
The rest of this post refers to the Delco CS units
I happen to like the CS series of Delco alternators; they utilize a pulse width modulation scheme to control the magnetic field strength by pulsing the power to the rotor 400 times per second, and thereby control the field (magnetic).
The duty cycle (how long the pulse stays on and off) can be controlled in order to create a ?soft start? capability that is easy on things like electronics and computers and such.
It is next to impossible to know if a PLIS or a PLFS regulator is in the unit, you have to take the case apart and check the part numbers on the regulator.
Although testing via resistance and voltmeters can detect most variations, the test set up is best left to a test bench.
There are at least 14 aftermarket regulators for the CS alternators that I know of. The voltage regulator has 4 posts that supply various signals.
The terminals on the CS130 series alternator are as follows?
P-terminal can provide a 12V square wave to determine alternator speed, used by some ECM?s.
L-terminal is the lamp connection, with the lamp being fed by the ignition circuit, some regulators require a 35-ohm resistance inline with this circuit if no lamp is used, and otherwise alternator damage will ensue.
F/I-terminal has several duties depending on the specific regulator, some regulators have a resistor that is internally connected between the Field and Lamp terminal. Another regulator uses the F/I terminal to provide field duty cycle information to the vehicles Electronic Control Module or computer. These regulators are not interchangeable, but for our Jeeps, it hardly matters. For ECM related vehicles it can be of paramount importance.
S-terminal is a heavier gauge wire that is connected to the battery.
Since this is an electronic computer chip, always disconnect the battery before servicing, and do not EVER remove the battery cable when the engine is running. You may just destroy the regulator?s computer chip.
CS-Series alternators use diodes within the rectifier plate known as avalanche diodes. Original Equipment designs use avalanche diodes in both positive and negative plates with a forward voltage of 0.9V @ 100 Amps and an avalanche voltage of less than 40 volts.
We don?t need to go into Epitaxial Planar Diode structure, just suffice it to say that the OEM regulators are tested and function the best.
Most of the CS regulators use Application Specific Integrated Circuits (ASIC). And more to the point, Application Specific Voltage Regulator computer designed chips that are encased in a plastic housing.
Removing the top of the plastic case will reveal the surface mount technology integrated circuit designed chip inside.
A word about aftermarket products and alternators purchased at the automotive after-market stores.
In the VAST majority of cases, the only things that go wrong on alternators are the brushes wearing out (resulting in a weak magnetic field, this can be easily checked by placing a screwdriver against the alternator case), and the regulator/rectifier or diodes going bad.
The diodes almost always short out, this is why the battery drains and in the morning the vehicle does not start.
When the regulator goes, generally overcharging or undercharging are the symptoms, and if you have the ?L?-terminal connected to an interior lamp, the lamp will glow, giving you a fault indication.
So?brushes are cheap, 10 bucks will usually suffice, and diodes are not expensive either.
The regulators usually ship with new brush assemblies, and the regulator circuit is mounted on a heat sink and can be replaced, most brush/regulator assemblies cost under $35 dollars.
I will point out that unsoldering the lead connections of the stator field coil wires can be ?problematic? if not done correctly.
Otherwise that is all that needs to be replaced when overhauling these units, the regulator and the brushes.
Makes you wonder where all that other money is going, to get a re-built alternator, that is using some cheap aftermarket regulator that cost $5 dollars in quantity, which is the reason that it failed in the first place.
Well, there is my rant on the subject?
I will attempt to take a layman thru a quick synopsis of alternator theory, as there has been much discussion on the message board about this subject matter.
When an electric current is passed through a conductor, a magnetic field is generated around that conductor. The reverse is also true, in which a conductor which moves across a magnetic field develops a voltage.
Current will flow if a complete electrical path is provided.
This is the principle of ElectroMagnetic Induction (EMI), and is one method of inducing a voltage in a wire that is either cutting or being cut by a magnetic field.
To further illustrate this physics principal, imagine two bar magnets placed end to end, the North Pole on one magnet facing the South Pole on the other magnet. You now have a magnetic field that is present in the space between the magnets.
Passing a length of wire through this space will create a voltage. This is termed an induced voltage.
How much induced voltage is dependent on the length of the wire that is passing thru the magnetic field, and how fast that wire is passed through that magnetic field.
The wire moving through the field can have different shapes. It might be a straight wire, or perhaps a coil or loop of wire, or even loops of wire. The longer the wire passing through the magnetic field, the greater the voltage induced on that wire.
An increase in the magnetic field produces an increase in the induced voltage. Also, the greater the speed at which the wire moves thru the magnetic field, the greater the voltage.
It doesn?t much matter if you move the wire or move the magnetic field, both activities will generate a voltage. If the magnetic field is increased, an increased voltage will be induced, if the magnetic field is reduced, a reduced voltage will be induced.
This is because of the magnetic fields physical properties, they have lines of magnetic force that flow from the North Pole to the South Pole.
The magnetic field that is developed and surrounds a current-carrying conductor can be visualized as spreading in a radial pattern outward from the conductor. Much like ripples of water when a stone is dropped into water.
Now, just as in magnets, like charges repel each other, and unlike charges attract each other.
Those magnetic lines repel each other, the stronger ones are the ones nearest the magnetic poles, since they repel other lines of magnetic force, other lines are moved further away, and so on and so forth.
So, getting back to how all of this works, we find that we can manipulate the speed, the distance, or the magnetic field strength applied, in order to manipulate the induced voltage.
If we increase the magnetic field, then the conductor cuts through more lines of force for a given distance traveled. A stronger magnetic field has its lines of magnetic force more tightly bound. Increasing the number of lines of magnetic force that are cut in a given distance and time, increases the induced voltage.
The laws of physics also indicate that changing the angle of the conductor that is passed through a magnetic field will influence the induced voltage.
A 90-degree angle has been shown to create the greatest induced voltage. By 90-degrees, we are referring to perpendicular, like a knife slicing a bread loaf. The further one deviates from this 90-degree angle, the smaller the induced voltage. This is similar to slicing that loaf of bread, if we cut it at an angle, the knife has to travel longer to cut thru the same vertical distance of the loaf, and transferring this ?bad analogy? to the alternator, magnetic lines of force can be cut at 90 degrees, and thus travel a shorter distance in a given period of time. Thus they cut more magnetic lines of flux, thus generating increased voltages.
Another interesting physics property to note is that if we pass the conductor back and forth thru the magnetic field, the voltages that are induced will be of opposite polarities from each other.
One direction thru a magnetic field will induce a positive voltage, and reversing that same conductor (the opposite way) thru the magnetic field produces an induced voltage that is of the opposite polarity. Even though there is no change in the conductor, or the magnetic field, only in the direction of travel.
So, moving a conductor back and forth thru a magnetic field causes voltage to be induced and the voltages will be of opposite polarities of each other.
In review of these basics, we can state the following?
The greater the speed of a conductor that is moving thru a magnetic field, the greater the induced voltage.
The longer the conductor, the greater the induced voltage.
The denser the magnetic field, the greater the induced voltage.
The closer to 90 degrees that the conductor cuts across the magnetic lines, the greater the voltage.
Another way to put all this is to simply state that:
The induced voltage is directly proportional to the rate of speed of the conductor cutting through the magnetic lines of force, all other things being equal.
In this sense, the rate of speed can also be tied to the number of magnetic lines of force that the conductor passes thru in a given time frame. Increasing the speed or length of the conductor or magnetic field strength will all result in increasing the induced voltage.
The same can be said of the opposite, reduce any of the properties mentioned, and the induced voltage will be reduced in direct proportion.
If the conductor that the magnetic field is passing through is part of an electronic circuit, then current will flow in proportion to the induced voltage. The induced voltage creates the current flow, and if you can find a way to prevent the voltage from rising, then the current has to increase, limit the current and the voltage needs to rise.
An alternator has a coil of wire wound around a Ferro-resonate material. In this manner, an electro magnet is created, because voltage is applied to this coil, current flows thru it, and they create a magnetic field. This magnetic field is polarized, which simply means that it has a North Pole and a South Pole.
When a current-carrying wire is wound into a number of loops to form a coil, the resulting magnetic field is the sum of all of the single loop magnetic fields added together. Increase the loops making up the coil, and you increase the magnetic field.
In review, the rotor of an alternator has an iron core, which is called an armature. This rotor or armature has copper wire wrapped around it. Passing 12Vdc to this coil of wire, results in current flow, which in turn produces a magnetic field and magnetizes the iron core, thus making the field (magnetic) denser. The rotor is heavy and is supported in the alternator housing via front and rear bearings that support a shaft, outside the alternator, a pulley is mounted on this shaft, to engage the alternator belt, which is driven by the pulley on the crankshaft.
So, now we have a dense magnetic field and as the engine speed of the vehicle increases, we can see how the density of that magnetic field increases.
Here is a hint?want to know if the Brushes on the alternator need replacing, put a screwdriver against the alternator, being careful not to get it hung up on anything, and check out the magnetism that the alternator puts out. With time, you can ?feel? the difference in magnetism intensity, and judge ?good? brushes and ?bad? brushes.
The stator of the alternator is made up of three loops or coils of wire that are mounted to the housing of the alternator, which are stationary. The rotating magnetic field whirls through these coils of wires inducing a voltage. Now, since this rotating mass is changing the angles of the field strength (magnetic field) as it rotates, the induced voltage and the current that these stator loops carry vary accordingly.
Each stator loop coil creates a 360-degree voltage that is known as a sine wave. The induced voltage gradually increase until the angle is at 90 degrees (peak inducement), and as the angles decrease again, the voltage decrease correspondingly; until the magnetic field begins to approach another set of stator loops or coils of wire, and the process starts all over for that particular loop coil.
In our alternator example, we have three loops of wire, and these three loops are placed such that a sine wave in each loop is generated. A complete revolution of the rotor assembly, which is 360 degrees of revolution, gives us three overlapping voltages that are 120 degrees apart (360 divided by 3 equals 120). The configuration of the windings causes these Alternating Current (AC) sine waves to overlap each other,
Once the AC voltages are created, we need to modify them because our Jeeps run on 12Vdc. The battery is responsible for supplying power to the electrical loads, and the alternator is responsible for keeping the charge rate of the battery within design limits.
These overlapping sine waves have their negative going voltages chopped off by diodes, and thus we end up with a series positive humps of DC voltage.
Electronic components in the regulator circuit smooth out this voltage, in order to generate the 13.5Vdc to 14.5Ddc, required by the battery for topping off its charge.
We are generating the AC voltage needed, in order to rectify or alter it, to produce a voltage that is sufficient to charge a battery.
The alternator is a three-phase generator with a built-in rectifier circuit consisting of six diodes in a full-wave bridge rectifier circuit.
In essence the diodes are solid-state switches with no moving parts, making them maintenance-free.
When they fail, they usually short.
When the rectified DC from each of the three-phase windings is added together or superimposed upon each other, the positive peaks overlap to produce a much cleaner DC with much less ripple.
Lead-acid auto batteries last longer when charged with pure DC than high ripple rectified DC. Three-phase windings were designed into alternators to produce DC of great purity.
As the pulley is rotated by a belt, (connected to the automobile engine's crankshaft), the rotor is spun past a stationary set of three-phase windings that make up the stator.
Recall that changing the magnetic field will change the induced voltage. Automotive engineers take advantage of this fact by altering the field strength of the alternator (rotor assembly) in order to correspondingly change the output of the alternators DC voltage.
Speaking of the rotor, you may be wondering how in the heck do we get reliable electrical connection to a rotating assembly?
The engineering folks used a clever set of copper "rings" incorporated into the shaft of the rotor assembly. Stationary ?carbon brushes" are held in firm contact with these ?slip rings? by spring pressure. This supplies the voltage required by the rotor assembly to create the magnetic field.
Many modern alternators are equipped with built-in "regulator" circuits that automatically switch battery power on and off to the rotor coil to regulate output voltage.
It is the regulators that control all of this rectifying and modulation of the field strength, in modern day alternators. Some regulators are designed so that the field strength is such that it will not produce an output in the stator windings until a minimal threshold level is overcome.
That is why some vehicles need to have the engines revved, so the alternator ?kicks in?.
If you lend that vehicle to a very soft-footed individual, it is conceivable that they will not exceed this threshold in the daily driving and you will be chasing your tail around trying to diagnose a phantom problem.
The operator is at ?fault? here, and needs to get up on the freeway once and awhile.
This seldom happens, but stranger things have happened.
Some of the alternators used are the Delcotron 10-SI with 3 cooling vents
0 amps at 1200 alternator rpm
23 amps at 1600 alternator rpm
60 amps at 5000 alternator rpm
Some of the alternators used are the Delcotron 12-SI with 6 cooling vents
0 amps at 1600 alternator rpm
30 amps at 2000 alternator rpm
70 amps at 6000 alternator rpm
The CS-130 105 amp Delco alternator
50 amps at 1600 alternator rpm
100 amps at 4000 alternator rpm
The SI moniker stands for System Integral or internal regulation.
The rest of this post refers to the Delco CS units
I happen to like the CS series of Delco alternators; they utilize a pulse width modulation scheme to control the magnetic field strength by pulsing the power to the rotor 400 times per second, and thereby control the field (magnetic).
The duty cycle (how long the pulse stays on and off) can be controlled in order to create a ?soft start? capability that is easy on things like electronics and computers and such.
It is next to impossible to know if a PLIS or a PLFS regulator is in the unit, you have to take the case apart and check the part numbers on the regulator.
Although testing via resistance and voltmeters can detect most variations, the test set up is best left to a test bench.
There are at least 14 aftermarket regulators for the CS alternators that I know of. The voltage regulator has 4 posts that supply various signals.
The terminals on the CS130 series alternator are as follows?
P-terminal can provide a 12V square wave to determine alternator speed, used by some ECM?s.
L-terminal is the lamp connection, with the lamp being fed by the ignition circuit, some regulators require a 35-ohm resistance inline with this circuit if no lamp is used, and otherwise alternator damage will ensue.
F/I-terminal has several duties depending on the specific regulator, some regulators have a resistor that is internally connected between the Field and Lamp terminal. Another regulator uses the F/I terminal to provide field duty cycle information to the vehicles Electronic Control Module or computer. These regulators are not interchangeable, but for our Jeeps, it hardly matters. For ECM related vehicles it can be of paramount importance.
S-terminal is a heavier gauge wire that is connected to the battery.
Since this is an electronic computer chip, always disconnect the battery before servicing, and do not EVER remove the battery cable when the engine is running. You may just destroy the regulator?s computer chip.
CS-Series alternators use diodes within the rectifier plate known as avalanche diodes. Original Equipment designs use avalanche diodes in both positive and negative plates with a forward voltage of 0.9V @ 100 Amps and an avalanche voltage of less than 40 volts.
We don?t need to go into Epitaxial Planar Diode structure, just suffice it to say that the OEM regulators are tested and function the best.
Most of the CS regulators use Application Specific Integrated Circuits (ASIC). And more to the point, Application Specific Voltage Regulator computer designed chips that are encased in a plastic housing.
Removing the top of the plastic case will reveal the surface mount technology integrated circuit designed chip inside.
A word about aftermarket products and alternators purchased at the automotive after-market stores.
In the VAST majority of cases, the only things that go wrong on alternators are the brushes wearing out (resulting in a weak magnetic field, this can be easily checked by placing a screwdriver against the alternator case), and the regulator/rectifier or diodes going bad.
The diodes almost always short out, this is why the battery drains and in the morning the vehicle does not start.
When the regulator goes, generally overcharging or undercharging are the symptoms, and if you have the ?L?-terminal connected to an interior lamp, the lamp will glow, giving you a fault indication.
So?brushes are cheap, 10 bucks will usually suffice, and diodes are not expensive either.
The regulators usually ship with new brush assemblies, and the regulator circuit is mounted on a heat sink and can be replaced, most brush/regulator assemblies cost under $35 dollars.
I will point out that unsoldering the lead connections of the stator field coil wires can be ?problematic? if not done correctly.
Otherwise that is all that needs to be replaced when overhauling these units, the regulator and the brushes.
Makes you wonder where all that other money is going, to get a re-built alternator, that is using some cheap aftermarket regulator that cost $5 dollars in quantity, which is the reason that it failed in the first place.
Well, there is my rant on the subject?
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