Charging System Question

[Dave48]

I have an 81 XS Special that I'm trying to rewire. I have two schematics. One is an original Yamaha schematic and one is a basic schematic I printed from a query on this forum.
The question I have is: both schematics show three white wires from the generator/alternator to the voltage rectifier/regulator. The Yamaha schematic shows two additional wires, a brown (voltage wire) and a green wire going to the rec/reg. What is the purpose of these two wires? I know the three white wires are the generator charge coils. The basic schematic does not show these two additional wires.
Also, why are there two voltage wires (1 red-1brown) connected to the rectifier/regulator?
My understanding of charging systems is you have the charging coils in the generator/alternator going to the rectifier, converting the voltage to unregulated DC, then to the regulator for regulated DC, then to the battery for charging. What are all these extra wires for?
Dave

 

[EvenmoreXS]

Not exaclty what youre looking for but here is the diagram I created and used.....IT WORKS ! For me anyway..... I did get a great description of exactly how all this works but I dont want to quote it and be wrong so I will try to find my thread and link it here so you can read it. Once understood, ... it makes sense....Stay tuned

 

[XSLeo]

On your stock alternator the three white wires do indeed carry electricity from the stator to the reg/rec. These wires carry AC voltage. The rectifier half of the reg/rec converts this AC to a more useable DC voltage.
Also on your stock system you have a field coil inside the rotor. This field coil uses power from the battery to create a magnetic field that as the rotor spins the stator creates electricity. The regulator half of your reg/rec controls the current flow through the rotor. If you look on your stock diagram you will see that the brown wire feeds battery voltage to both the reg/rec and one of the brushes on the stator.
The brown and green wire to the alternator are wires to the brushes.
Now when you turn on the key, battery voltage goes to the brushes on the brown wire, from the one brush through the rotor, out the other brush then through the green wire to the reg/rec.
Battery voltage also goes to the reg/rec. This is for voltage sensing. Now with the key on, the battery gets drawn down a bit by the electrical system. Below the reg/rec's preset voltage of 14.5. Senceing the low voltage the reg/rec gro8unds the green wire to let current pass through the rotor. Now when you start your bike, the strong magnetic field of the spinning rotor excites the stator into creating AC voltage.
As before, thus AC flows to the reg/rec, gets converted to DC and gets sent to the battery on the red wire. The black wire goes to ground to complete the circuit.
This flow of DC charges the battery. As the battery voltage rises, it will at some point reach the reg/recs preset voltage of 14.5 volts. The reg/rec now senses full battery charge and shuts of the flow of current in the rotor, thus stopping the charge.
It repeats the on/off cycle thousands of times a minute to keep the battery charged.
This is called a field excited alternator.
Now on your simplified diagram if the reg/rec doesn't have the green and brown wires to the stator then you have a PMA or Permanent Magnet Alternator.
This type of alternator doesn't use a field coil. It has permanent magnets for the magnetic field to excite the stator to create the AC voltage. The PMA reg/rec does the same AC to DC conversion.
The way it controls the output is different. On a PMA the permanent magnet can't be turned on/off like the electro magnet of the stock system. This causes the PMA to put out the max current all the time.
The reg/rec controls the output by shunting excess voltage to ground. Now as the voltage rises on starting, when it reaches 14.5 volts this shunt starts to bypass voltage to ground. So anytime the out put is over 13.5 volts powers gets shunted to ground.
If your simplified diagram is for a PMA. You can't use that diagram with your stock alternator.
In the 'Some Wiring Diagrams" thread scroll down to #4 it shows a very basic diagram of a point system. It also has the later combo reg/rec parts in a box, just swap the early box for the later. It also has the TCI in a box, if you are using the TCI just swap the points box out for the TCI.
If you are running a Pamco just wire it in after the engine stop switch.
Leo

 

[EvenmoreXS]

On your stock alternator the three white wires do indeed carry electricity from the stator to the reg/rec. These wires carry AC voltage. The rectifier half of the reg/rec converts this AC to a more useable DC voltage.
Also on your stock system you have a field coil inside the rotor. This field coil uses power from the battery to create a magnetic field that as the rotor spins the stator creates electricity. The regulator half of your reg/rec controls the current flow through the rotor. If you look on your stock diagram you will see that the brown wire feeds battery voltage to both the reg/rec and one of the brushes on the stator.
The brown and green wire to the alternator are wires to the brushes.
Now when you turn on the key, battery voltage goes to the brushes on the brown wire, from the one brush through the rotor, out the other brush then through the green wire to the reg/rec.
Battery voltage also goes to the reg/rec. This is for voltage sensing. Now with the key on, the battery gets drawn down a bit by the electrical system. Below the reg/rec's preset voltage of 14.5. Senceing the low voltage the reg/rec gro8unds the green wire to let current pass through the rotor. Now when you start your bike, the strong magnetic field of the spinning rotor excites the stator into creating AC voltage.
As before, thus AC flows to the reg/rec, gets converted to DC and gets sent to the battery on the red wire. The black wire goes to ground to complete the circuit.
This flow of DC charges the battery. As the battery voltage rises, it will at some point reach the reg/recs preset voltage of 14.5 volts. The reg/rec now senses full battery charge and shuts of the flow of current in the rotor, thus stopping the charge.
It repeats the on/off cycle thousands of times a minute to keep the battery charged.
This is called a field excited alternator.
Now on your simplified diagram if the reg/rec doesn't have the green and brown wires to the stator then you have a PMA or Permanent Magnet Alternator.
This type of alternator doesn't use a field coil. It has permanent magnets for the magnetic field to excite the stator to create the AC voltage. The PMA reg/rec does the same AC to DC conversion.
The way it controls the output is different. On a PMA the permanent magnet can't be turned on/off like the electro magnet of the stock system. This causes the PMA to put out the max current all the time.
The reg/rec controls the output by shunting excess voltage to ground. Now as the voltage rises on starting, when it reaches 14.5 volts this shunt starts to bypass voltage to ground. So anytime the out put is over 13.5 volts powers gets shunted to ground.
If your simplified diagram is for a PMA. You can't use that diagram with your stock alternator.
In the 'Some Wiring Diagrams" thread scroll down to #4 it shows a very basic diagram of a point system. It also has the later combo reg/rec parts in a box, just swap the early box for the later. It also has the TCI in a box, if you are using the TCI just swap the points box out for the TCI.
If you are running a Pamco just wire it in after the engine stop switch.
Leo

It doesn't get much better than that.....if any......I think leo wrote that same thing to me a year ago.....

Infinite wisdom........or at least a big shit load of it.

 

[Dave48]

Leo
Thank you very much. That is what I needed to know.
Dave

 

[XSLeo]

I did a write up on this a while ago. If you look up in the tech section under the electrical you will find it. "Explanation of the Basic Electrical System" is the link.
I started with the points system then covered the later TCI system differences.
Leo