Understanding The R/r Inside And Out

[Tightwad]

OK, it has been bugging me for a long time that the Honda R/R has such hard times on our bikes...so I decided to see how they worked, and see if I could come up with another alternative. I am placing this topic here as it isn't really year specific, but is certainly Electrical...and maybe someone will get something out of it. I am not an Electrical Engineer, nor am I a professional. Any advise dispensed is purely theoretical and practical use, with no guarantees of any sort written or implied.

How the charging system works:

The Honda VFR (and most modern motorcycles) employs a 3-phase Permanent Magnet alternator. This means there is a magnet attached to the crank shaft, which rotates around the Stator and creates an electro magnetic field....basically the opposite of an electromagnet. The VFR Stator has 18 "stacks" around which magnetic wire is wound in a precise manner. The more windings the more voltage. The bigger the wire, the more amperage you get. The only limits are space, money, and horsepower.

See this link for understanding how to rewind a stator....yes you can do it if you want (not sure I would want to), the link is for a 2 phase, but the general principles are the same:

http://www.4strokes.com/tech/honda/brpstatr.asp

So then what? We now have an AC producing device, which isn't incredibly useful on a vehicle that uses DC power. We also have a device that is wound in such a way as to produce normal voltages of 65 VAC. Change this to DC and you still have 65 Volts (minus one or so for diode loss of course). Well, we need to change that current to DC current first...so we use diodes in a Bridge Rectifier. By using a diode, which only allows voltage to flow one direction, we can turn AC voltage to DC voltage.

Now 1 diode will give you just DC voltage, but it would be incredibly voltile...as it would go from 0 volts to max volts and then back to zero. That would be for a single phase....for three phases you would go from zero to max, down a bit then back to max(phase 2), then down a bit and back to max again(phase 3), then to zero while the AC current went the other direction. By using the diode bridge, we turn the negative side into DC voltage also, so we get 6 peaks from one cycle....3 that were positive to begin with, and 3 that were negative buy became positive via the diodes....you get a constant high voltage, with little dips between the peaks. These oscillate so fast you can only seem them using an oscilloscope.

This image shows just one phase:

Three phase wired together looks like this:

So the resulting output is:

Congrats...you now have DC voltage! Thats all we need isn't it?

Of course not...that would be too easy. How easy? It would be this easy:

But the problem is, the voltage is not limited. I measured the output I got:

1200 RPM - 28 Volts

2000 RPM - 38 Volts

3000 RPM - 56 Volts

4000 RPM - 78 Volts

5000 RPM - 96 Volts

6000 RPM - 117 Volts

7000 RPM - 138 Volts

8000 RPM - 156 Volts

9000 RPM - 173 Volts

10000 RPM - 192 Volts

My meter only reads to 200, so I stopped here. This means we need an effective way to reduce the output to a usable level....ie 12-15 volts at max. The way it is currently done is by shunting the excessive current to ground. directly from the stator....when output voltage exceeds need, the phase in action goes to ground. This is a similar design to what is used in most Motorcycle Regulator/Rectifiers today:

By using an SCR (Silicone Controlled Rectifier) we can control when the grounding happens. SCR's are pretty cool...when set correctly you can trigger them just by touching them....like those touch lamps everyone has played with at some point. Is this the best method? No one seems to have a better one. What is the side effect? The side effect is heat, and lots of it....thus we need a way to bleed off the heat, thus the importance of a good heat sink, including cooling fins and airflow.

Stay tuned, as my next step will be to re-create the circuit above and create controlled output!

Edited January 8, 2011 by HispanicSlammer
edited to feature photo on homepage

[alwaysaware]

I thought that I had a clear understanding of how the electrical system on the bike worked before reading this post. Now I'm all confused trying to interpret your schematics. Thanks for that posting it was very informative. :fing02:

[Tightwad]

I thought that I had a clear understanding of how the electrical system on the bike worked before reading this post. Now I'm all confused trying to interpret your schematics. Thanks for that posting it was very informative. :fing02:

Whups, I was trying to help people understand better through my research. The schematic posted (last picture) is the inner workings of your R/R. The Monitor wire may or may not exist...some are internally monitored and some are externally monitored.

[CitizenOfDreams]

Bravo Tightwad, nice explanation.

How about a crash course in thermodynamics now (for those of us who tie-wrap a CPU fan to the rectifier/regulator thinking it will drastically help cooling it)?

[Bad Boy]

I would like to know what causes the stator to overheat and melt.

[Guest Gap Trash]

YOU PEOPLE make me feel dumber all the time.

[blkcruzer]

I would like to know what causes the stator to overheat and melt.

1200 RPM - 28 Volts

2000 RPM - 38 Volts

3000 RPM - 56 Volts

4000 RPM - 78 Volts

5000 RPM - 96 Volts

6000 RPM - 117 Volts

7000 RPM - 138 Volts

8000 RPM - 156 Volts

9000 RPM - 173 Volts

10000 RPM - 192 Volts

It is dumping about 175-180 volts that are extra and grounding them @ 10k, there is your source of heat!!

[Steve128]

YOU PEOPLE make me feel dumber all the time.

+1

[Bad Boy]

I would like to know what causes the stator to overheat and melt.

1200 RPM - 28 Volts

2000 RPM - 38 Volts

3000 RPM - 56 Volts

4000 RPM - 78 Volts

5000 RPM - 96 Volts

6000 RPM - 117 Volts

7000 RPM - 138 Volts

8000 RPM - 156 Volts

9000 RPM - 173 Volts

10000 RPM - 192 Volts

It is dumping about 175-180 volts that are extra and grounding them @ 10k, there is your source of heat!!

It is the rectifier that is dumping the excess electricity and creating heat. What I want to know is what would cause 3 stators to melt down?

[Guest Gap Trash]

How does a R/R work? Hows a rainbow made? whys the sky blue? how does a posi track rear end on a plymouth work? It just does.

[CitizenOfDreams]

I would like to know what causes the stator to overheat and melt.

Excessive heat - which is caused by excessive current - which is (as I understand) often caused by a short circuit in the rectifier/regulator.

[Guest benisonfire]

How does a R/R work? Hows a rainbow made? whys the sky blue? how does a posi track rear end on a plymouth work? It just does.

+9000

[fastrc46]

Awesome post! Very well done :fing02:

[Tightwad]

I would like to know what causes the stator to overheat and melt.

Excessive heat - which is caused by excessive current - which is (as I understand) often caused by a short circuit in the rectifier/regulator.

My non-professional opinion....

The R/R is the "weak link" as it has the most parts that CAN fail. Stators by themselves rarely fail because they are just a bit of metal with wire wrapped around it. The R/R on the other hand is full of bits and pieces that all need to work correctly. Besides the Diode Bridge, there are 18 other electrical components in the schematic I posted. Most likely to fail is the Diode Bridge (no charging) or the SCR (Shorts to ground, creating tons of heat). If the Stator is melting, which would be an incredible amount of heat, or just getting hot enough that the wire covering melts....covering is rated to ~133 C, or 271 F, it would most likely be because the R/R is not shorting the power to ground correctly.

[Tightwad]

How does a R/R work? Hows a rainbow made? whys the sky blue? how does a posi track rear end on a plymouth work? It just does.

My problem is that I have never been good at accepting "it just does" as a valid answer, but those dang Posi-tracks still have me baffled.

[chrisford]

Is the excess voltage sent out via one of the wires to the connector? If so wouldnt increased corrosion/dirt/muck (creating poor contact) in said connector increase resistance there by increasing heat to said connector there by MELTDOWN? So wouldnt the connector be the weakest link?

If excess voltage is not sent out via one of the wires then wouldnt increase resistance in the connector still cause increase heat via increased resistance still causing MELTDOWN of the connector, so the connector is still the weakest link?

Now if the previous questions are completely wrong i'll accept any and all tongue lashings :unsure:

[Bad Boy]

I would like to know what causes the stator to overheat and melt.

Excessive heat - which is caused by excessive current - which is (as I understand) often caused by a short circuit in the rectifier/regulator.

My non-professional opinion....

The R/R is the "weak link" as it has the most parts that CAN fail. Stators by themselves rarely fail because they are just a bit of metal with wire wrapped around it. The R/R on the other hand is full of bits and pieces that all need to work correctly. Besides the Diode Bridge, there are 18 other electrical components in the schematic I posted. Most likely to fail is the Diode Bridge (no charging) or the SCR (Shorts to ground, creating tons of heat). If the Stator is melting, which would be an incredible amount of heat, or just getting hot enough that the wire covering melts....covering is rated to ~133 C, or 271 F, it would most likely be because the R/R is not shorting the power to ground correctly.

Thanks for this informative thread. I am with you, I want to understand this so I can prevent stator #4 failure when I am several days away from home. I think this is understandable so far. I understand electrical theory enough to be dangerous but not enough to solve this.

Here are questions. As the stator operates, what happens to the stator when the power demand or resistance of the R/R is excessively high or low? Would either condition heat the stator?

At a given rpm does the stator put out a constant wattage or is it dependent on the R/R resistance.

I would guess the R/R resistance or draw from the stator should be fairly constant and what power is not used by the bike is wasted in heating the R/R. As the bike draws more current there would be less heat at the R/R and when the bike draws more current (amps) than available the system voltage would drop.

[Guest VFR_NZ]

The R/R is the "weak link" as it has the most parts that CAN fail. Stators by themselves rarely fail because they are just a bit of metal with wire wrapped around it.

This is correct. This is why it is better to run with full load on the electrical system ie lights ON, then the regulator only has to disipate a small amount of power. The rectifier section will not create much heat because on on resistance of the diodes is very low.

A very good post.

Wayne

In New Zealand

[Guest sandman]

How does a R/R work? Hows a rainbow made? whys the sky blue? how does a posi track rear end on a plymouth work? It just does.

My problem is that I have never been good at accepting "it just does" as a valid answer, but those dang Posi-tracks still have me baffled.

It works on the principle of PFM.

Pure F-ing Magic!

Now you know. :unsure:

[Guest VFR800Boy]

Good topic, and one close to all our hearts..

Almost 5 years ago my 98 VFR800 had the R/R fix done by a local genius (City Auto Electrics in Coburg)

Now I hear a buzzing noise from behind the side cover.

Is it the reg/rect? Has anyone else experienced this?

[turtlecreek]

I would like to know what causes the stator to overheat and melt.

Excessive heat - which is caused by excessive current - which is (as I understand) often caused by a short circuit in the rectifier/regulator.

My non-professional opinion....

The R/R is the "weak link" as it has the most parts that CAN fail. Stators by themselves rarely fail because they are just a bit of metal with wire wrapped around it. The R/R on the other hand is full of bits and pieces that all need to work correctly. Besides the Diode Bridge, there are 18 other electrical components in the schematic I posted. Most likely to fail is the Diode Bridge (no charging) or the SCR (Shorts to ground, creating tons of heat). If the Stator is melting, which would be an incredible amount of heat, or just getting hot enough that the wire covering melts....covering is rated to ~133 C, or 271 F, it would most likely be because the R/R is not shorting the power to ground correctly.

Thanks for this informative thread. I am with you, I want to understand this so I can prevent stator #4 failure when I am several days away from home. I think this is understandable so far. I understand electrical theory enough to be dangerous but not enough to solve this.

Here are questions. As the stator operates, what happens to the stator when the power demand or resistance of the R/R is excessively high or low? Would either condition heat the stator?

At a given rpm does the stator put out a constant wattage or is it dependent on the R/R resistance.

I would guess the R/R resistance or draw from the stator should be fairly constant and what power is not used by the bike is wasted in heating the R/R. As the bike draws more current there would be less heat at the R/R and when the bike draws more current (amps) than available the system voltage would drop.

being a simple mechanical convertor, yes the stator puts out constant wattage at constant rpm. r/r decides what to do with it (waste it/send to electrical system)

i believe your statement about heat to be correct to a degree. power transfered to the electrical system still creates heat in the r/r as it is not 100% efficient, but less heat as the heat is not created in the electrical system devices that are consuming the power instead of being dumped to ground in the r/r. however, the available system voltage does NOT drop as that is the exact goal of the r/r. only when your system draw is so high that the r/r can no longer produce enough power will the voltage drop.

[wrestler]

YOU PEOPLE make me feel dumber all the time.

What's up Gap!!!

[Tightwad]

I now have 98% of the parts needed to make my own R/R, and test some theories. More to come on this topic as I actually do something.

On a side note, I now know how to make an adjustable low amperage voltage regulator, which I needed to correctly set the on-off point of the R/R. I also obtained some high-amp parts that will hopefully not fry something.

[Bent]

You don't make IED's do you?? :blink:

Wouldn't put it past Dale.... :ph34r: :cool:

[CitizenOfDreams]

I now have 98% of the parts needed to make my own R/R, and test some theories. More to come on this topic as I actually do something.

:cool: Patiently awaiting for more details (description of your experiments, schematics, photos of buckets full of smoked FETs...)