Basic question about current management.

[VFan]

I have read at multiple sites, including this one, that a poorly charged battery or a defective battery will place an excessive load on the stator and burn it out. It's not clear to me how this happens.

My current understanding is that a stator is an open loop device that generates current through induction. The variables in the stator's production of current are: size of the magnets, the amount of wiring wrapped on the stator, or how fast the wiring is moving across the magnets. Because it's open loop system it's unaffected by loads that are placed on the R/R.

The R/R converts the current from the stator from AC to DC and limits the voltage to ~ 13.8 v. My assumption is that the R/R is essentially a watts limiter, meaning that it not only regulates voltage, but it also bleads off excessive amperage as heat.

So with these assumptions that I've stated, I can visualize how an excessive load or a defective battery could burn out a R/R, but I'm not able to visualize how the stator can be affected.

Does my question make sense? What parts of the picture is incorrect or incomplete?

Thanks

[Lucky]

I think we all agree, at this point that what causes OUR stators to fail is excessive heat and possably vibration as an aggravating contributor..
the stator doesn't care what happens with the current once it's done with it..

--Lucky

[QBS]

VFan, you got it.

[Walt_M.]

Thanks Vfan, excellent description of the system. Also Lucky's explanation of the basic problems.

[YellowJacket!]

LOL... I saw the title of this thread and thought it was a complaing about Ron, our faithful Admin.  :D

David

[VFan]

LOL didn't think about it that way.  ;D 

[h2olawyer]

I had the same thought as David.   ;D

H₂O

[VFan]

So I have a question for H20

If I read your comments correctly from the "bold stator claim" thread, you assert that a bad R/R will burn out a stator. I'm trying to reconcile my understanding, described above, with your experiences. Thoughts?

[Lucky]

It's because H20's vision is SO FAST, his stators can't keep up!! ;D ;D ;D

So I have a question for H20

If I read your comments correctly from the "bold stator claim" thread, you assert that a bad R/R will burn out a stator. I'm trying to reconcile my understanding, described above, with your experiences. Thoughts?

[h2olawyer]

Actually, it was probably that I was so slow that my stators were outpacing me.  The bike would go 1000 miles, but for as many hours as the bike was running, the stator thought it had gone 10,000!  About the time I finally gained a larger comfort level riding faster, (late last summer), the stator started lasting longer.  (2500 miles out of the last one)  Now that I'm keeping up with a known good rider on his VFR800 in most situations, maybe my stators will finally last a long time.   ;D  Yeah, that must have been the problem . . .

H₂O

[kwells]

ah...an updated theory.

[Lucky]

Since we're talking stators, i wonder if having Macs, since there is no left side pipe, helps keep the stator case cooler? no pipe to add heat or block airflow..

Betcha it helps!!  ;)

--Lucky

[VFan]

OK, as long as we're talking heat is there any merit in exploring the idea of coating the winding with a higher quality, more heat resistant epoxy? I've read a couple threads inspecting a worn out stator that mentioned that the epoxy had deteriorated significantly.

[h2olawyer]

The real issue is what is causing the excess heat?  Keeping exhaust away from the stator side can't hurt.  But, what happens is that the stator grounds out on one of the windings & turns the stator into a heating element for a little while.  That's what crispies the epoxy coating near the short.  The entire stator will turn dark colored over time, but the spot where the stator shorts to ground has burned epoxy flaking off.  At least that's been my experience.

H₂O

[Kenny]

 If you are thinking about heat managment -move your feet to the back pegs or see the difference in a crosswind.

                               cheers Ken S. ;)

[Coil Coyle]

#1508 has 2,000 mile since the crank bolt drilling and it has a 20,000 mile replacement stator from the early 90's that was already showing toasted oil crustiness that was evenly coating the windings. No oil cooler, just drilled the bolt.

I can't search the old post but Lucky had one dimension for the whole and I think mine was larger and longer. Its posted under #1508 or Dean's bike if your search works.

From pancakes I know that the toasty oil is from 375f +

I agree with H2O that once a single winding shorts to another nearby, that length of the winding goes very high current and you get the burnt band on a single coil.

$0.02

I thought this post was going to be about Ron, too.

:laugh:

Coil