They Dont call it "Sparks and Magic" for Nuttn

[posplayr]

EDIT: Feb 1 , 2011 These charts are over stated because they do not include the saturation effects of the magnetics. I provided acutal SHUT Vs. SERIES current measurements here: SHUNT_vs_SERIES_RR_Compare_Tutorial

How about this Boys and Girls, wanna see what a Permanent Magnet generator power characteristic looks like?



Here is a reference I found for this graph.

http://www.ktu.lt/lt/mokslas/zurnala...20Geometry.pdf

Basically it confirms what I posed a couple of days ago. The power generated in the stator is going up to the square of the RPM.

Voltage is proportional to RPM
V=K*RPM
Power = P = V^2/R
so
Power = P = (K * RPM)^2/R
Power = (K*RPM)^2




Here is a spreadsheet I put together to compare the difference between

• OEM
• FET R/R
• 20% increased Power from stator with FET R/R

The big problem here is when you are operating in the 5K to 7.5K RPM zone for sustained periods. This is basically where I'm at when riding Hwy 33 in the twisties.

At 5K RPM the R/R is at about 2K watts a little more power than a Hot hair dryer. But by the time you get to 7500 RPM the power has gone up 150% to 5KWatt which is like having more than 3 1500W hair dryers on. With a 20% increased output I have 4 1500W hair dryers on my stator

While the FET based stator does increase the power in teh stator marginally (50 watts), the big issue is the total power getting generated in the stator.




It is no wonder why this thing is turning brown.

http://www.thegsresources.com/_forum/showthread.php?t=160008

http://www.thegsresources.com/_forum/showthread.php?t=159898

Anyone want to guess what this is ?

[Agemax]

a generator cover with a widget on it?

[kochic]

Oil cooling?

[posplayr]

Oil cooling?

Yep, I'm going to slowly work up on the restrictor orifice size. Right now about 1mm and I'm still running 10-12 psi at 5K hot. Seem a little lower at idle hot (3 psi)

Note: Oil restrictor is about 0.090"

[posplayr]

Here is a pic of a OE Kawi 550/750 (early 80's) stator and a OE GS 1100E. There is thicker wire and less wraps on the Kawi. It also loosk much better.
The Kawi is slightly larger OD than the GS, will have to carefully check if it will fit. Chef says it does.




Edit: The stator on the right that the PO had installed at a dealership looks remarkably like the Ricks's below.

[Matchless]

Jim,
Very very interesting! As you know I rewound my stator nearly two years ago with slightly heavier wire and maximum turns, a few more than it had on originally. I found much better charging at lower RPM's and my voltmeter jumps to 14.2V at about 1200 RPM's.
I never reach the RPM's that you refer to..... my age must be showing!

The following are just some thoughts and not statements:

What this also shows is that a higher output stator could be at more risk (overheating) than a more sedately wound one if your bike runs at high or very high RPM's and maybe more so with a FET R/R.

If this is correct then the stator windings should really be matched with the engine RPM capability to some extent. A bike with a max 8k and another with a max 14k RPM may not have similar stators? This also means that similar physical size stators may not really be as interchangeable as we would like to think. It could also mean that non OEM stators with "improved" or higher output may be risky.

Using a FET R/R is good as the R/R is then quite bullet proof, but maybe the stator needs to be "underwound" a bit to actually reduce the higher RPM output.

With shunt type regulation you ideally need an alternator that does not put out more current than what is required by the load, but can supply the extra current needed to charge the battery if it is discharged. So in reality adding LED lights to reduce the load and "upwinding" the alternator to provide more amps (albeit at lower RPM) is not really as efficient as we thought and using the new FET R/R could all lead to overheating of the stator!

There must obviously be some sort of upper and lower limits that the R&D engineers use to cover all these variables and that will be a sort of compromise between theoretical figures and tested limits when it comes to use in the field.

I have now suddenly started worrying about my stator!! It never bothered me untill now!

Keep well.

[posplayr]

Jim,
Very very interesting! As you know I rewound my stator nearly two years ago with slightly heavier wire and maximum turns, a few more than it had on originally. I found much better charging at lower RPM's and my voltmeter jumps to 14.2V at about 1200 RPM's.
I never reach the RPM's that you refer to..... my age must be showing!

The following are just some thoughts and not statements:

What this also shows is that a higher output stator could be at more risk (overheating) than a more sedately wound one if your bike runs at high or very high RPM's and maybe more so with a FET R/R.

If this is correct then the stator windings should really be matched with the engine RPM capability to some extent. A bike with a max 8k and another with a max 14k RPM may not have similar stators? This also means that similar physical size stators may not really be as interchangeable as we would like to think. It could also mean that non OEM stators with "improved" or higher output may be risky.

Using a FET R/R is good as the R/R is then quite bullet proof, but maybe the stator needs to be "underwound" a bit to actually reduce the higher RPM output.

With shunt type regulation you ideally need an alternator that does not put out more current than what is required by the load, but can supply the extra current needed to charge the battery if it is discharged. So in reality adding LED lights to reduce the load and "upwinding" the alternator to provide more amps (albeit at lower RPM) is not really as efficient as we thought and using the new FET R/R could all lead to overheating of the stator!

There must obviously be some sort of upper and lower limits that the R&D engineers use to cover all these variables and that will be a sort of compromise between theoretical figures and tested limits when it comes to use in the field.

I have now suddenly started worrying about my stator!! It never bothered me untill now!

Keep well.

I agree with most except for the most part the riding habits of how much RPM for how long has a much larger effect than anything else. The FET does contribute some (30 watts perhaps at 5K RPM) but a small rise in RPM can controbute much more.

Unfortunately there is not much way to do anything about this short of disabling winding. I have a couple of ideas.

In the mean time more oil can't hurt as long as I don't starve my engine. . I have plenty of pressure

Of course we have to remember the engine is running at 250-300 degF anyway, so the stator is going to get hot regardless. It just can't get so hot as to cook and burn (500-600 degF).

[SqDancerLynn1]

I would be curious, was the over heated leg on top or bottom

[TheCafeKid]

Wow Jimmy. You should go to work for BMW or MBZ or something! Show them Germans how to REALLY over engineer something!
the fact is boys and girls, you're trying to re-engineer somethig that is nearly 30 years old. For all the effort you're going to to prevent stator failure you could have installed one of those starter gear driven alternators that one guy sets up and be done with it. As it is you have now possibly compromised your oiling map, and at best added yet another fitting that will eventually leak. If you're doing it because it entertains you more power to you my good friend. But given the circumstances involved, I'll take my chances. I've more pressing problems to attend to on a thirty year old bike that sees heavy use. That's all I'm sayin.

[posplayr]

I would be curious, was the over heated leg on top or bottom

It is the dry top which is brown.

[posplayr]

Wow Jimmy. You should go to work for BMW or MBZ or something! Show them Germans how to REALLY over engineer something!
the fact is boys and girls, you're trying to re-engineer somethig that is nearly 30 years old. For all the effort you're going to to prevent stator failure you could have installed one of those starter gear driven alternators that one guy sets up and be done with it. As it is you have now possibly compromised your oiling map, and at best added yet another fitting that will eventually leak. If you're doing it because it entertains you more power to you my good friend. But given the circumstances involved, I'll take my chances. I've more pressing problems to attend to on a thirty year old bike that sees heavy use. That's all I'm sayin.

Josh,
Thanks but the problem is the charging system is under-engineered, I'm simply solving a problem I have(as reported it is primarily a rider ridding habit issue.

I'm apparently alone in spending alot of time over 5K. Maybe not I think Cliff is having a similar problem.

Oh and remember I over engineered my dash as well so I know exactly what my oil pressure is.

[BassCliff]

Hi,

I do spend a lot of time over 5000 rpm. Being on the So. Cal. freeways means 75mph+ which, for me, is 5500 rpm or more.

I'm really hoping that the thicker wire and fewer windings on this Rick's stator lasts longer than the Electrosport and RM Stator parts. I'll keep you informed.


Thank you for your indulgence,

BassCliff

[Matchless]

Unfortunately there is not much way to do anything about this short of disabling winding. I have a couple of ideas.

Of course we have to remember the engine is running at 250-300 degF anyway, so the stator is going to get hot regardless. It just can't get so hot as to cook and burn (500-600 degF).

I am sure you are into this already and we can soon expect a comprehensive report on this! Maybe you would like to compare the use of the Delta and the Wye configuration for any better or worse affect in this case.

Your coated stator seems to have a finishing coat of high temp powder coating, that is how the wires themselves get so neatly coated. If they used a brown colour, you would not have noticed anything!
The Kawa one seems to have an clear epoxy finishing coat which is normal for many OEM stators.

Keep well.

[posplayr]

I am sure you are into this already and we can soon expect a comprehensive report on this! Maybe you would like to compare the use of the Delta and the Wye configuration for any better or worse affect in this case.

Your coated stator seems to have a finishing coat of high temp powder coating, that is how the wires themselves get so neatly coated. If they used a brown colour, you would not have noticed anything!
The Kawa one seems to have an clear epoxy finishing coat which is normal for many OEM stators.

Keep well.

I did not realize that was powdercoating. I just went to Casewell to read about the different coatings. It seems that epoxy is most applicable. It cures at 400 degF . The stator has to be geeting well above 400 degF.

http://www.caswellplating.com/powder/powder_colors2.html

while the winding configuration will have some impact, it is not going to change the fact that power keeps going up to the square RPM. I knew this in the past but had assumed that there would be a roll-off in power due to magnetic core saturations which are typical in other DC motors. I did not realized later that there is essentially no roll-off in the PM.

With the rotor/stator being sized to basically provide full load capacity at 2000 RPM, by the time RPM gets to 8000 RPM (4:1) the power is 16:1.
This is not something that can be practically disappated or controlled in electronics without something to significantly alter the gross power output of the windings.

For example , what maybe feasible is to wind the stator as two sets of parallel windings ( in phase on the same stator). There would be 6 wires leaving the stator. A voltage or speed sensitive FET based device could open the 2nd pair of winding once the speed had exceeded some value. The output, would be three remaining wires from basically a 1/2 stator to drive a conventinal R/R.

Racers must get rid of these things. What is even harder to imagine is how modern sprots bikes deal with this if they can rev to 15K rpm!!!!

The other aspect that I'm been discussing with my buddy is the fact that the primary means of cooling is heat condution into the engine.He was actually surprised the stator was not bolted to the motor for better heat conduction. Taking a detailed look, the heat path from stator through the little mounting neck and then through the cover to the cases is far from ideal. There has to be alot of heat radiating into the rotor which is why those can also look a little toasty.


Well it is hard to argue with a burnt stator, but some people will

[TheCafeKid]

Jim modern sportbikes use alternators. Which is also part and parcel as to why they can spin up to such absurd rpms. ( along with modern components etc). My point was merely that you are trying to change something that seemed to work well enough for 20 or 30 or more thousand miles. Hell my es still has the original factory stator in it and it's fast approaching 50 thousand miles. Still charging fine. FET regulator and all. If your new stator lasts half that long for $120 bucks or whatever it was you're doing pretty well. I've had car alternators crap out on me faster. If you don't think I spin my bike up to seven grand or more on a regular basis, you haven't been to Kentucky or West Virginia or southern indiana. ride more. Worry less. If it bugs you that much carry a spare. You're letting the engineer in you eat you up
and btw. You know what your oil pressure is at the gallery and or at the gauge. A plugged port elsewhere will only increase it in a small amount. 3lbs of pressure isn't much to keep track of.
Don't mistake me. It's your bike, your mind that you have to settle and all that. Normally I'm hot on your coat tails with your latest fix or fidgit, but this, this is a whole nother bag of worms. But I'm no engineer so what do I know?