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Nope, The rectifier is a three phase bridge, all of the three phase AC (including the negative-going part of the sine wave) is used in making DC! Very efficient! :smile2:

None of the three legs of the alternator go negative with respect to the Bike's ground because there's no ground reference anywhere in the alternator, even the common point of the three phases floats. Thus the negative-going part of the sine wave is referenced to bike's ground thru the negative-rail diodes in the bridge, thus driving the positive-going legs to an even higher output.

I wasnt saying negative pulse referring to the ground, only in reference to the direction of flow within a given winding and the diodes blocking or conducting direction. You say potato, I say tomato....
 

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Automotive electronics are spec'd "nominally" at 13.8V (14 really) and not 12 volts, so you are only 1.3 volts over when reading 15.1 volts. Sensitive low voltage internal circuits will have built-in voltage regulation which is necessary because the input voltage can vary so much. Your electronics will tolerate up to 17 volts all day long.... and if your voltage is THAT high you DO have a problem.
I wonder if Denver or John would explain the floating ground thing. I think I sort of understand it but certainly not very good.
To get started I will tell you what I think and it could be wrong. I know when the alternator spins it makes AC in the form of a sine wave. If the sine wave was in sync with the bike (would this mean it is non*floating?) one half of the sine could be used and one half would be wasted. Does a floating ground make it possible for the sine to actually be shifted to be more positive? So,,,,even when the alternator sine has switched direction and is headed down, some of that wave is still more positive than the bike. Therefore more than half of the sine can be rectified and used to charge the bikes battery. Is any of this right? I know electronice use a lot of floating grounds on cars and trucks. Seems like they use them on a lot of reference signals. Am I even close?:wink2:
 

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You are going to have to forget what you know about a Sinewave single output winding, that has the negative side of the diode tied to "Ground". This will produce only positive going pulses, or "dead air", if you like on the negative going half of the cycle.



With Alternators, the Wye connection, of a 3 phase system, ( floating ground ) is not connected to anything except the the common points of each of the 3 windings in the Alternator and the center of the Diode Stack.



Calling the center Wye connection a "Ground" is very misleading, and really confuses the issue for those who are not in the habit of reading schematics.



The Bridge type Rectifier catches the Negative going pulse, and outputs it to the charging system properly.



It is the output of the Bridge Diode Stack, that actually has the "Ground/Negative" connection, and the Plus ~13.6 VDC output terminal.



you need to follow the schematic closely to see what is going on, just take one leg at at time and note how it finally makes it way to the Plus, and Minus terminals of the Diode Stack.


The output voltage is regulated by controlling the amount of current into the Field of the Alternator, which in turn controls how much magnetism is generated in the poles of the stator. ( frame of an alternator )
 

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OK, you have now established a point of confusion. The "common" connection in a Wye or star connected winding is not ground but common. The"ground" is made by the physical connection of the anodes of 3 diodes to the alternator case( or negative terminal in an isolated output alternator). What about the case of a "delta" connection. It has three common points, each tied to the center point of a pair of diodes (anode of one , cathode of the other). The opposite ends of the diodes become the positive and negative outputs(X3).

Or the Ford alternator with 8 diodes ( 2 tied to common).

I believe that most alternators are now a delta connection, to get higher output currents in a smaller package.
 

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I Hadn't seen the Ford configuration before... Hmmm... Don't see why not - the Additional diodes on the common point are certainly another opportunity to make current!

A buddy of mine was having charging issues on his Moto-Guzzi 1100. I tested the alternator, Surprised me that it only had a SINGLE PHASE output. Found plenty of AC juice there. So that thing must have only a basic 4 diode bridge... Told him he needed a new Rec-Reg module.

John Said:
"You are going to have to forget what you know about a Sinewave single output winding, that has the negative side of the diode tied to "Ground". This will produce only positive going pulses, or "dead air", if you like on the negative going half of the cycle."

Only applies if you are using a single Diode rectifier. With a four diode bridge, you have full-wave output.
 

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Only applies if you are using a single Diode rectifier. With a four diode bridge, you have full-wave output.

True, if we are only referring to a single winding, and no other windings are involved.


I wrote my last post from "memory", and did not consult the manual for the Goldwing's Alternator..... sorry if I side tracked the thread a bit there.


I had forgotten the Goldwing uses a Delta configuration.


I need to sue that 18 wheeler guy again for short changing my memory forever.... :frown2:
 
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