How to Predict Catastrophic GL1200 Stator Failure


Step-by-step tutorials on how to maintain and fix your GL1200
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HawkeyeGL1200
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by HawkeyeGL1200 » Wed Apr 01, 2015 8:56 am



I just feel fortunate to be surrounded by people who are smart enough to figure stuff like this out. My electrical knowledge is sorely laking when compared to many of you and information like this is priceless... despite the fact I have to look up half of what you're writing about so I can understand it. Really good information.. thanks!


I am wrong as often as I am right concerning what is wrong with someone else' motorcycle without having seen the machine in person. Guessing with limited information, as to the source of the trouble, is sketchy at best.

Ken Styles
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Ken Styles » Mon Aug 10, 2015 8:10 am

What exactly is a "stator" Is it like an alternator for a car?

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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by wingingit2 » Mon Aug 10, 2015 9:40 am

The stator is a stationary coil in the upper rear of a Goldwing motor. There is a rotating permanent magnet inside the stator creating AC current. Together they are similar to an alternator with an external regulator/rectifier.The difference is you don't replace the whole thing. The stator, magnet, reg/rect are replaced as needed.
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Ken Styles » Mon Aug 10, 2015 10:14 am

ooh ok, great thanks!

Didn't know.

I keep seeing posts about Stators and wanted to see if mine ever goes bad if I can pin-point exactly if it would be the source of the problem.

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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by wingingit2 » Mon Aug 10, 2015 11:04 am

You would need to check the 3 yellow wires, from the stator, under the LH side cover for resistance to each other and each to ground. Equal resistance to each other, near 0 ohms, and no continuity to ground.
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Rednaxs60 » Fri Apr 29, 2016 1:02 am

Scot Thompson wrote:A series regulator will do no good with a permanent magnet alternator. However, you can improve the situation with the R/R on these old wings by using a MOSFET R/R. I the factory SCR, the heat one feels is mostly from the swiching going on internally (in the silicon) that shunts the unused power to ground. This happens on all 3 legs of the output of the alternator to the R/R and that is a good thing as some really cheap designs just shunt one leg to ground to regulate the voltage. This switching consumes some power and it takes some time. When the electrical current is switched to ground, it is wasted and we feel that as heat. In the case of the SCRs on the GL1200s, that amounts to about 66 watts...or about the amount of heat a 60-watt light bulb puts out. That is why the R/R is not all the time. But it is designed to deal with this amount of heat, so they should function for a long time. In a MOSFET R/R, the switching function is vastly quicker than the older SCR design and therefore less power is consumed regulating the voltage level. So more power is available to operate the bike; you still have the same shunting to ground occurring though.

Why the series regulator is not useful for a permanent magnet type of alternator is that in a series regulation design, the magnets on the rotor are electro-magnets that require some input voltage to produce a magnetic field. The more voltage supplied to the electro-magnet, the stronger the magnetic field created. The stronger the magnetic field is, the higher the output of the stator as the magnetic fields pass by the coil windings. No input to the electro-magnets, no output of the stator. This is how the level of power is regulated on a series design. On the GL1200s, the rotor contains permanent magnets that produce a constant magnetic field...always, even at rest. These magnetic fields, when rotating, pass by the stator coils and in doing so, an electrical current is induced. The faster the rotation of the constant strength magnetic field, the higher the level of current created at each coil of the stator. Nothing regulates that except the speed of rotation of the rotor. So, in order to regulate a permanent magnet alternator, the power is shunted to ground and turned into heat.

When the stator component of the alternator starts to "bleed" to ground, on one, two or three of the phases, it is still possible to have some output. Even as the electricity is going to ground. Each of the three legs (the phases) of the stator will produce about 70 VAC, so if, say, a short to ground is consuming 40 volts, there is still 30 VAC being passed to the R/R. That is why a stator that is failing can still produce enough power to the R/R in order for the R/R to rectify the alternating current into direct current and pass that to the regulating function of the R/R. Should the rectifying function receive 70 VAC from 2 phases and 30 VAC from the third phase, the level of output is still higher than 12.8 volts (nominally) and therefore the regulating function will still attempt regulate its output. My alternator on my GL1200 is putting out adequate AC power on two legs, and about 10% power on the third phase...because that leg is shorting to ground within the stator. But the bike still sees 14.2 VDC. It just cannot accept much load (the combination of voltage and current being consumed) and with all the lights on, it will fall to about 12.5 VDC and that will not keep the battery charged. (I PoorBoy'd the bike and left the partially functioning alternator intact.)
Apologize for resurrecting this old thread; however, just installed the SH847 series RR from roadster cycle.

Initial start of the bike and all was well. Went to do a test ride and no charging.

Disconnected the stator plug from the SH847, and tested the stator. No continuity between phases and no continuity to ground. With the bike started and the stator connector disconnected from the new RR, no AC output.

It was mentioned above that there is a need to have an electrical input to the electro-magnets to get an output from the stator.

I will put together a harness and connect the old RR up again to determine if it is the new series RR or not. The new series RR may be good, but will not work on an '85 LTD.

Cheers

More to follow.
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by flash1942 » Fri Apr 29, 2016 8:53 am

If you have NO continuity between the stator phases then you have a bad stator. The stator should have NO continuity to ground.
The series type RR modulates each phase and gives the bike only the voltage it is calling for, thus the stator gets a "rest"between power demands. The PM type of power generation does NOT need an exciter voltage to make it function. The series RR stops current from coming from the stator windings when power requirements are satisfied. Makes sense to me.
The shunt type RR (any type) causes the stator to continually produce maximum power and if all that power isn't needed then it shorts it to ground where it's wasted in the form of heat. If you stop this insane and archaic way to "manage" power generation then you may have a longer stator life, provided you don't try to exceed the system's designed output as some may try with lights aplenty. I suspect that our stators can put out far more than it's ratings therefore increasing the possibility of melting wires into.
If any of you electrical engineers see differently then please clue me in..........

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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by wingingit2 » Fri Apr 29, 2016 9:22 am

I am not an "Engineer" but it is my info the a permanent magnet stator is always producing 100 percent power given the RPM. That is the reason extra power is shunted to ground.
A series RR will vary the output of an excited alternator by varying the strength of the electromagnet, not possible with permanent magnets. That is why a Moffset RR works better on our Wings than a Series RR.
When I install a Moffset RR I create a new harness for it. A positive, and a negative to the battery, and 3 new Yellows direct to the stator.
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Rednaxs60
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Rednaxs60 » Fri Apr 29, 2016 11:17 am

Will take this to my own thread. Cheers
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by SlowTyper » Fri Apr 29, 2016 2:19 pm

Being the poster that began this thread, let me try to summarize some things in one reply that may be helpful to future readers of this thread.

The big difference between an automotive alternator and a GL1200 stator is that one uses an electromagnet and the other uses permanent magnet. In an alternator, power fed to the electromagnet is increased/decreased as needed to obtain the desired output. With a stator, since the strength of the permanent magnet cannot be altered, the only way to change the output is to change the speed of the permanent magnet movement -- in other words, speed up or slow down the engine.

Because it is totally impractical to adjust the output of the stator by changing engine RPM, there has to be another way. In their infinite wisdom, Honda chose to convert the extra unneeded output power to heat! This is why the regulator normally runs hot. The faster the engine runs and the less electrical load, the more unwanted excess energy that will exist and need to be converted to heat. (If you want your regulator to run cooler, add lights to you bike and ride slower in a higher gear. Just don't get too carried away with this, or you will overdue it and not have enough power to prevent your battery from going dead!)

As far as a MosFET regulator is concerned, most work the same way as the Honda regulator. That is, they still convert the excess power to heat by shorting out the stator windings. The only difference is that MosFETs are more efficient than SCRs, which results in the regulator running cooler. But in either case, the shunting of the stator windings is very hard on the stator and any connectors involved with the three yellow wires.

Unfortunately, I am not familiar with a series MosFET regulator. I am speculating that this implies that the regulator operates in series with the stator, rather than in parallel. (Somebody can hopefully enlighten me on this.) In that case, rather than shunt/short-out the stator to quash the excess power, the regulator would disconnect the stator. This approach would be much kindler/gentler to the stator and wiring. I actually contemplated designing one that works this way for my bike, but abandoned the project over concern about the voltage spikes that would occur when the stator was abruptly disconnected. (Disconnecting the stator would be functionally equivalent to opening the points on an older ignition system -- high voltage is momentarily generated at the moment of disconnect.)

And although it has been stated many times, to summarize again, with the stator disconnected from the regulator and the engine not running, the resistance between each of the three yellow wires should be very low (less than an ohm). And there should be no continuity between the yellow wires and ground (the engine casing). If there is measurable resistance to ground, then the stator windings have shorted to the iron core they are wound around (or the yellow wires have shorted to the casing). And finally, the AC voltage between any two of the yellow wires should be around 70 volts at engine idle, but more importantly, the AC voltage should be identical when compared between one pair and the other pair and the third pair, when the engine RPM is constant between measurements. If this voltage is not the same between pairs, it indicates a discrepancy between windings. This may indicate a poor internal connection or one turn of wire is shorted to an adjacent turn of wire in the windings.

Lastly, pay attention to any new stator you install. I saw a situation where the yellow wires shorted to the aluminum plug where they exit the engine! But that is a subject for a new thread...

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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Rednaxs60 » Fri Apr 29, 2016 2:27 pm

Thanks for the update. Checked the stator this morning. Continuity between all phases - no continuity to ground, and less than 1VAC on each phase when engine running. It is the lack of VAC, and the consistency between each phase that is stumping me.

More investigation to be done.

Cheers
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by SlowTyper » Mon May 02, 2016 2:13 pm

Rednaxs60 wrote:Checked the stator this morning. Continuity between all phases - no continuity to ground, and less than 1VAC on each phase when engine running. It is the lack of VAC, and the consistency between each phase that is stumping me.
It seems a bit odd to me that all three stator phases have completely shorted out. I would have expected that by the time one or two phases shorted, you would have stopped riding and started troubleshooting. The fact you do not have more than 1VAC across at least one yellow pair combination makes me wonder if something else is being overlooked.

I am not familiar with the mechanics of the rotating permanent magnet, but am wondering if it is possible for it to have come loose and is not turning any more. I am not saying it is impossible, but it seems peculiar that all the windings would be sufficiently shorted that they no longer produce any voltage, but yet none are shorted to the iron core they are wound around.

Unfortunately, I know of no practical way to measure the inductance of the stator windings, which would indicate whether or not adjacent turns of wires are all shorted together. The resistance of the windings themselves is so low that it is almost impossible to distinguish between shorted turns and not. (Usually, the windings also short out to the frame, which is easy to measure. But your measurements to ground indicate this has not happened.)

Although it is not very scientific, you might consider quickly striking each pair of yellow wires across battery voltage. If the windings are shorted between turns, you will get a horrendous spark when the wire makes contact and not so much when disconnecting. (DO NOT make this momentary connection near any battery gases!! Battery gas is highly explosive; I have seen a battery that exploded due to a spark at the battery terminal, and the person involved was very nearly seriously injured.) If the windings are not shorted, then you will see a minimal spark when making the connection and a nice bright spark when the wire is quickly removed from the voltage. In essence, in this scenario, the stator acts like an ignition coil and generates a high voltage spike when power is removed suddenly -- unless the windings are shorted out (shorted turns effectively shunt the magnetic fields generated by the application and removal of voltage). Just do not make this type of connection very long, as the stator is not designed for DC voltage. A few connections for a fraction of a second each should be adequate. If much DC voltage is applied for a long time, heat will build up and you will have shorted turns whether or not they were shorted previously.

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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Rednaxs60 » Mon May 02, 2016 2:29 pm

SlowTyper - going to go in and investigate. Have to do a repair because of the wiring. Bare wires with VAC in them is not good, and as expected, too close to the engine case to do a repair of the wires. Have a shop here that can check the stator but cannot rewind it. More to follow.

Cheers
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Re: How to Predict Catastrophic GL1200 Stator Failure

Post by Rednaxs60 » Sun May 29, 2016 9:30 am

Slowtyper - have the engine out, new stator (using Electrosport), doing other things a swell that will keep me riding for a long time. Have rebuilt the starter clutch and everything is good regarding chains, etc. The rotor did not stop turning, so it has to be something else with the stator. For the rotor to not be turning there would have to be a catastrophic failure of other parts in the engine.


The stator for the '85 LTD looks very well built, is encased in epoxy and there are no splits, etc in this epoxy coating:


The internal wiring leaves a bit to be desired:


I saw on another thread of yours that you changed the wires on a stator. I'm thinking this would be a good project for the winter and see what the stator does.

Cheers


"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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