Stator is getting so hot the wires at the phase connections melting

Good to know about it being a shunt reg. Just because I am the curious sort would you happen to have a part number of a series reg. When I went searching (trolling) the net bout the mosfet regs I ran across the sv site where they were using the FH008?? reg with great results and some were also using the FH016AA which is what led me to the zx6r reg/rec to begin with.

HAHA yeah it would be just my luck that now I will have problems with my stator. Fingers crossed that is not the case.

Clayton
 
It's been recommended to get a series reg/rec, but I'm not convinced it's necessary to spend four times as much. A high quality MOSFET shunt should work fine, as you are demonstrating.

An SCR shunt regulator may even be better than the MOSFET regulator if keeping the stator cool is your primary goal. Shunt regulators work by converting excess electricity into heat. The big selling point of the MOSFET regulator is that it runs cooler, but if it is running cooler then where is the excess power being dissipated? More than likely the heat is transferred to the stator windings.
 
I recently did a stator swap for a friend, replacing the HHB stator with a Nippon Denso unit. The Banshee bracket had to be machined to allow the thicker stator to fit behind the rotor.

The rotor itself looked about half done. The taper was roughly turned and didn't fit the crankshaft, and there were no drill marks to indicate that it had been balanced. An hour or so with a bearing scraper and lapping compound corrected the taper. I had no way to balance it so I have no idea how far off it was (if at all).

Good to know. I have an ND stator on its way from eBay. I was hoping it would be a direct swap with the HHB stator. I have no machining capabilities, but I'll find a way to shorten it, if I need to. Some sandpaper on a flat surface and hope it comes out level? :thumbsup:

Same deal with my rotor. Did not have anything to indicate it had been balanced, but it may not have needed it.

How did you notice that the taper was off? Mine went on without the woodruf and stayed in place for its short lifespan on my bike. It definitely made a POP! when I busted it off with the rotor puller.
 
I just did a little reading and found that a SH775 is a series SCR regulator. Through "some sort of black magic voodoo" it only conducts for part of the generating cycle thus resulting in lower reg/rec and stator temps. They can be sourced fairly cheaply here ($63 +shipping). Looks like I may be doing a little tinkering...........

I need to get an ir temp gun.

Clayton
 
An SCR shunt regulator may even be better than the MOSFET regulator if keeping the stator cool is your primary goal. Shunt regulators work by converting excess electricity into heat. The big selling point of the MOSFET regulator is that it runs cooler, but if it is running cooler then where is the excess power being dissipated? More than likely the heat is transferred to the stator windings.

Last week I read this insanely long and detailed thread on the topic.

http://www.apriliaforum.com/forums/showthread.php?240785-Facts-about-shunt-based-regulators

It lead me to believe that a quality mosfet shunt is the way to go. The guy also recognizes that series regulators have a zero failure rate on their bikes. So... Either one. A mosfet shunt is cheaper than a quality series unit.
 
I have no machining capabilities, but I'll find a way to shorten it, if I need to. Some sandpaper on a flat surface and hope it comes out level?

If you do it by hand then you should find some way to rig up a dial test indicator to verify that the stator remains concentric with the rotor. If it rubs you will toast the rotor. Even if it doesn't rub, the stator coils will not be loaded equally if the gap between the stator and rotor varies from one side to the other.

How did you notice that the taper was off? Mine went on without the woodruf and stayed in place for its short lifespan on my bike. It definitely made a POP! when I busted it off with the rotor puller.

The first indication was when the rotor came off just by screwing the puller in by hand. The fact that yours "popped" off is a good sign.

To check the taper, I colored a line on the crank with a Sharpie then spun the rotor on the shaft to see the contact points.

TaperFit.jpg


After fitting it, the contact pattern looked like this.

TaperFitFix.jpg
 
Awesome, thank you for the tips. I was thinking I'd sand right off the top (outward facing) surface. Now I see that there are three tabs that center the stator:

DSC_0023.jpg


If I removed those, the stator could be mounted off axis. I don't have a dial indicator.

The whole banshee bracket and adapter plate feels... Flimsy... Janky... to me, anyway. You had it right with the one piece, cast mounting plate. Do you know if the XSCHARGE piece, which I believe was inspired by yours, mounts the ND/V30 stator without modification?

Or... Wait... Is it the HHB rotor that is the outlier?

Thanks!
Adam
 
Do you know if the XSCHARGE piece, which I believe was inspired by yours, mounts the ND/V30 stator without modification?

Or... Wait... Is it the HHB rotor that is the outlier?

As far as I know, the aftermarket rotor has the same spacing as the stock Banshee rotor.

The clearance issue [when running a thicker stator on the HHB setup] is caused by the adapter plate behind the Banshee bracket. I made my bracket the same height as the Banshee bracket [with no adapter plate]. I'm not sure how tall the XS Charge bracket is.
 
I've been following these threads, and I just gotta be honest. I have a HHB PMA myself and find it off putting that Hugh himself isn't responding to any of this. My engine has barely ran since the install and from I saw I wasn't thrilled with my voltage readings. Again, I said barely ran so it may be something simple like a bad ground but still, it bothers me that Hugh isn't chiming in. Clear answers would be nice.
 
Last week I read this insanely long and detailed thread on the topic.

http://www.apriliaforum.com/forums/showthread.php?240785-Facts-about-shunt-based-regulators

That's a great read. Started 3 years ago, so it appears that this isn't a new or unique problem, sort of a random mystery. What I find amusing is that it's also:

Engineers discussing the various nuances and foibles of the PMA systems.
*** versus ***
Members who just want to know what part to buy.

As you already know, I have no dog in this hunt. But I do love to throw chum in the water.

So, here's something else to consider: Induction Heating

Induction heating, which occurs whenever a metal (especially iron) is exposed to an alternating magnetic field, has been used for decades for metal hardening processes and (more recently) for cooking. It's highly desirable in those applications, not so in transformers and power generators.

Careful considerations are necessary to reduce this phenomena in power transmission field coil applications, and those industries have gone to great lengths to research and minimise this. Some of the variables that can influence this are:

Core material selection
Core construction (laminations)
Core design
Core manufacture (tight, properly overlapped laminations)
Exposure frequency (especially if the design becomes resonant)
Magnetic flux intensity
Short/open/loaded coil circuit (influences the core inductance, hence the resonant frequency)

With improperly designed and manufactured cores, it may be possible that the PMA overheating may be due largely to this effect.

So, here's the next scenarios. Maybe:

The manufacturer's choice of lamination material was changed, due to costs, and a non-suitable choice of sheet metal was used, altering the core's inductance to a non-desirable value.
Lamination assembly was sloppy and/or incorrect.
The inherent frequencies of the shunt regulator's actions on the coils cause the stator to experience harmonic resonance at the particular frequency of the passing rotor magnets.
The manufacturer is clueless, or doesn't care.
RG's sunspot theory is correct.

How to detect this from a cursury inspection of a new stator?

I have no idea...

Edit: This Induction Heating phenomena can also occur in the ROTOR, maybe even ruin the rotor's magnets...
 
Last edited:
I've been following these threads, and I just gotta be honest. I have a HHB PMA myself and find it off putting that Hugh himself isn't responding to any of this. My engine has barely ran since the install and from I saw I wasn't thrilled with my voltage readings. Again, I said barely ran so it may be something simple like a bad ground but still, it bothers me that Hugh isn't chiming in. Clear answers would be nice.

He probably is taking a christmas break the last time he was here was 12-16-2014 05:03 PM
He's a good guy.
 
Series regulators have been enthusiastically taken up by the Suzuki GS community as a cure for the notoriously bad stock regulators on those bikes. I think the stator problems with the HHB PMA kit are probably regulator based rather than stator based. This has proven to be the case with Electrosport products if I'm not mistaken. Plenty of people have successfully rewound their stators by hand, and I'm sure they didn't meet OEM quality guidelines when doing so, so I don't think the first stator pictured is a particularly bad looking item. SH775 regulators are cheap as chips, and I believe the latest V-Strom 1000 units are a higher current (50A) version of the same thing.

No matter what design your shunt regulator uses, it's causing the stator to run flat out all the time. The fact that the regulator itself runs cooler is great for the regulator, but the stator itself sees no benefit.
 
Series regulators have been enthusiastically taken up by the Suzuki GS community as a cure for the notoriously bad stock regulators on those bikes. I think the stator problems with the HHB PMA kit are probably regulator based rather than stator based. This has proven to be the case with Electrosport products if I'm not mistaken. Plenty of people have successfully rewound their stators by hand, and I'm sure they didn't meet OEM quality guidelines when doing so, so I don't think the first stator pictured is a particularly bad looking item. SH775 regulators are cheap as chips, and I believe the latest V-Strom 1000 units are a higher current (50A) version of the same thing.

No matter what design your shunt regulator uses, it's causing the stator to run flat out all the time. The fact that the regulator itself runs cooler is great for the regulator, but the stator itself sees no benefit.

Glad to see this thread is still interesting to others, it sure is for me. I received a ND stator a couple days ago. The insulation on the windings is noticeably better than the HHB Chinese unit. I also have a Shindengen FH012AA shunt regulator on the way (from an '08 R1). While it's still a shunt, it's a MOSFET unit, while the SH series are SCR. From what I have read, they are more efficient and accurate than an SCR unit.

From what I understand, a shunt regulator shorts to ground to regulate. A series regulator only completes the circuit when voltage low/below threshold. When a series regulator opens the circuit, there is no current, but that results in massive voltage in the stator. In theory, this is [just as bad | worse | the same]?

I am thinking/hoping that the SCR circuitry might be to blame, not the fact that it's a shunt design.

Unfortunately, I don't have a flywheel at the moment. I sent mine back to HHB (according to tracking, it arrived 8 days ago, but no confirmation/update from HHB). I'm tempted to buy a used Banshee flywheel to get this going, but the HHB unit should be fine. I don't want to buy parts I don't need.
 
Hey, Adam, it's interesting to me as well. Have some more thoughts on this, but will take a bit of time to put together a post, another likely scenario...
 
...From what I understand, a shunt regulator shorts to ground to regulate. A series regulator only completes the circuit when voltage low/below threshold. When a series regulator opens the circuit, there is no current, but that results in massive voltage in the stator. In theory, this is [just as bad | worse | the same]?

I am thinking/hoping that the SCR circuitry might be to blame, not the fact that it's a shunt design...

Trying to put this down without writing a book is challenging. It's difficult without a chalkboard and expressive arm-waving.
Basically, just thinking out loud. A lot of things are happening here. I hope the idea gets across.
Apologies to any EE's reading this, please excuse liberties taken in this rambling.

First, an over-generalized, over-simplified review of the basics:

Semiconductor Vf (Voltage drop in the forward, conducting direction) - Silicon-based semiconductor devices (diodes, transisters, SCRs, triacs, FETs, ...etc) demonstrate a voltage drop when current flows in the forward/conducting direction, normally around 0.6 - 0.65 Vdc, sometimes as high as 1.1 Vdc for large-current rectifying devices.
03253.png


This Vf is not the same as a resistor, which demonstrates a voltage drop proportional to current. As such, a semiconductor permits essentially unimpeded current flow once the Vf voltage requirement is reached.

Inductors - Current is reluctant to flow through an induction coil as it's trying to build a magnetic field. But, once the magnetic field is established, this current flow is reluctant to stop flowing, like a freight train with bad brakes on ice. Ref: Inductive kickback, Inductor freewheel effect.
03271.png


Inductive heating - Occurs when the magnetic flux changes, not just in the stator core, but also in the rotor, because it's experiencing reactive magnet field changes in the nearby stator arms.

Now, what happens in a single coil of the PMA (viewing this in very slow motion):

As a magnetic pole of the rotor approaches the stator coil, the magnetic flux changes in the stator arm, and causes current to start flowing through the coil.
Also, a little inductive heating occurs, in both rotor and stator, based on the magnitude and rate of change of this magnetic flux.
When the magnetic pole of the rotor is aligned with the stator coil, the magnet flux in the stator arm is established and the current flow is established.
As that magnetic pole of the rotor departs, the magnetic flux in the stator arm remains and current continues to flow, for a short decay period.
When the opposite pole of the rotor magnet approaches the stator coil, the magnetic flux starts reversing, and current flow thru the coil slows/stops/reverses.
Also, a little inductive heating occurs, in both rotor and stator, based on the magnitude and rate of change of this magnetic flux.
And the cycle repeats.

Current delivered out of the coil to the rectifier/regulator is replaced by current sourced from the other coils of the other 2 phases, thru the common tie point of the 'wye' configuration, or simply from the other end in the 'delta' configuration.

Now, here's the theory scenario:

When the regulator shunts the output of this coil to ground (via SCR or MosFet), the current will flow while it's above the Vf of the shunt device. This current is sourced from the backside by the other 2 phase coils thru their rectifier diodes tied to ground, closing the loop, but includes their Vf. (Need a better schematic here, I hope you can visualize this).

This Hayabusa schematic uses a delta-type winding, but if you follow the current flow arrows you can see how the circuit is a closed-loop during output shunting:
HayabusaPMA.jpg

suzuki-gsx1300-hayabusa-charging-circuit.png


If this shunted current doesn't decay rapidly enough, the residual magnetic flux in the stator arm will induce a larger-than-normal flux change when the next pole of the rotor arrives. Causing additional induction heating. And the cycle repeats.

If the shunt devices clip their grounding action soon enough, the current will be stopped before the next pole arrives, reducing the magnitude of the flux change, and the added inductive heating effect.

Factors influencing this would be:
The strength of the rotor magnets.
Inductance/reluctance of the coil/arm
The Vf of the semiconductors.
Control circuitry of the shunt devices (SCRs just conduct until a specified cutoff value)
RPMs and number of poles of the rotor (more magnets & rpm = less time to decay)).
Response rate of the shunt devices.
Plus more.

It would seem that when the engine is running at low enough rpms, that the residual flux probably decays rapidly enough to avoid this additional induction heating.
It would also seem that very efficient, long-duration-conducting shunt devices would produce this undesireable effect. Add to that very powerful rotor magnets.

A series-type regulator would clip the output current and arrest this coil freewheel effect. I can see why there's been no reports of PMA overheating with these.

Rambling mode off...
 
Last edited:
Interesting.

Just a quick anecdote. The auto transformer used as a soft start on the 12000hp compressor where I used to work experienced eddy current effects strong enough to make the heads of the bolts holding its cover on glow white hot during startup, so,yes, inductive heating can have some very bad effects.

It basically served as a rather large and noisy choke to limit starting current until the compressor was up to speed and the main contactor could pull in at full voltage, 7200VAC.
 
I've been waiting to respond until I could compare an contrast the HHB system and the "traditional used parts system." I just got the last piece of my non-china PMA parts in the mail, a banshee rotor, and fucking dropped it, breaking the magnets. It rattles. I want to punch a hole in my own face. So fucking frustrated.
 
I am following this discussion with great interest, as my 150 w "Powerdynamo" PMA is still in its box. On the other hand, I do know that the 150 w "Powerdynamo" PMA/CDI for RD350s work great. At least in a moderate climate, I hardly ever see more than 25 degrees C where I live, mostly between 10 C and 20 C in the summer. Also, I basically never experience traffic jams or prolonged high speed running (Low speed limits and very high speeding fines...)

But i still think there are some potential issues regarding this PMA overheating that I haven't seen mentioned in this discussion:

- Some OEM PMA setups are running in oil, like Ducatis and also 70's Honda singles. This would limit the stator winding temperatures to somewhat above the oil temperature. In fact, on some 90's Ducatis there was a recall for installing some spacers, to improve oil circulation around the stator windings. When using stators designed to run in oil, on an XS, that may become an issue.
- There is also the issue of the rated output of the PMA, higher output would require more cooling or it gives higher temperatures.
- When using a stator from one engine with a rotor from different engine, it may happen that the rotor has stronger magnets than the one the stator was designed for. This will increase the potential max output, thus increasing the thermal load on stator and also regulator.
-Based on the above, a RZ/RD 350YPVS/Banshee PMA should be fine, as these engines are 2-strokes, and the stators are designed to run dry. On the other hand, using a stator from a 4-stroke with a "wet" stator may not be that clever. And 'mixing and matching" rotors, stators and regulators may have its pitfalls too, unless doing really thorough research first.
 
I've been waiting to respond until I could compare an contrast the HHB system and the "traditional used parts system." I just got the last piece of my non-china PMA parts in the mail, a banshee rotor, and fucking dropped it, breaking the magnets. It rattles. I want to punch a hole in my own face. So fucking frustrated.

Damn Man, I'm feeling for You
 
Back
Top