Another alternator hits the dust and not under warranty

Below the same picture from above, the stator viewed from the LHS, that is from inside out.
In the second picture the stator seen from the outside, that is the side that is towards the outside of the bike.

Strange to see that on that side, the only charred part are the 3 poles where they connect to the outside wiring.
this wiring is the only part of the stator in fact that is touching the external cover. !!

here is the 2nd picture, the side facing the cover.

That looks like the insulation is breaking down with the close contact with the cover and causing a partial short to the case?
Joel what do you think of this localized burning up of the insulation?
Or since it is at the bottom is the hot oil charring the insulation?

How are the ends of the coiled copper wire connected to the soft wires coming outside? If it does run at full capacity all the time any imperfection in there would cause localized resistance (over)heating... just a thought.

I really like your approach to the problem, where most questions are the same I asked myself.

Checked a German forum and they only had two similar incidents. Not many considering the high number of F8's sold there.
What me concerns most is the fact that basically everything works fine and the problem occurs only after a certain mileage. Well, some exceptions seem to prove the rule.
So if heat is the problem why doesn't it kill the alternator immediately? Cowboys approach with the heat resistant tape sounds good but I doubt that the exhaust tubes really roast the alternator. I checked with my F8 and the tubes are in my opinion not a problem, at least not when riding, but the may be when going really slow and there's no air flow.
Like cowboy I can build up a plane (mechanically) but I am clueless about the electric stuff so I can't say anything to the different types of rectifiers and related stuff.

BMW sure knows whats going on and it pisses me no end that they don't state the reason. Knowing the reason would help to find a way to solve the problem....

Steveman:

Has BMW acknowledged the problem?

I'm sure average riding speed & temperature has a lot to do with it, also if bash plate shields air flow ... and so on...

Perhaps German riders as a group are riding faster in cooler weather, while US riders are riding slower and in hotter weather?

Are the only bikes that are having the stator failures have the bash plate installed?

Please don't let the bash plate be the cause, then mother ship will tell us in order to fix the problem you must take off the bash plate.

This IS the way stators fail. There are a few other types of failures but they are extremely uncommon. There is going to be more then one cause and different bikes may have a different primary cause.

The insulation on stators ages. Higher heat, higher peak voltage, higher ratios of contaminants in the oil, and weaker stator insulation will all cause the stator to fail quicker. I think we can deduce that we have a stator that under prevailing conditions, has a median lifetime of 30,000 miles. We also have some outliers that last much longer and a few that fail much earlier. Nature or nurture, I don't know.

Maybe the temp in the stator housing has gone up, but it doesn't need to. It is normal for a stator to age by slowly baking a little darker over a time. A complex and slow chemical reaction is occurring to all stators. They all age. At the instant one finally hits the state of deterioration that a hard short occurs, current goes through the roof and in a few minutes of riding, the whole stator turns black.

I wouldn't think exhaust temp is going up over time, but thats an interesting possibility. The F8, as apposed to the F650 DOES have air injection. Air is injected straight into the exhaust to allow the catalyst to do a better job, if for any reason there is more fuel in the exhaust, the bike is running richer or injectors are shooting a poorer pattern, after burning will occur and the exhaust will get considerably hotter.

Magnets don't get stronger with age, ever. That would be contrary to laws of the universe. But as to the rest, you seem to be thinking along the lines that the stator has to get hotter to fail. As described above, it doesn't. It ages over time and heat greatly influences the rate, then when the insulation finally breaks down too much, it shorts and turns into a mega burnt thing all at once rapidly. Thats why the picture shortly above is of great interest to me. Every failed stator I have seen has been a piece of slag thats not informative. The stator above was removed before it finished burning to death.

There is some conjecture here based on normal industry practice. Our type of charging system runs the stator flat out for current at whatever impedance causes the voltage to be 14.1 volts. Several laws are in place here. One states that the rate of change of a magnetic field will determine the voltage and that at a given resistance, will determine the amperage. BUT another law states that current flow in the stator will create a "back Elector Motive Force"' usually stated "Back EMF", or the lay term "armature effect". This means that at some point, current flow in the armature will create a magnetic force that apposes the magnets and at some point he two come to equilibrium at which point no more power will be produced no matter how low the demand resistance or rate of change of magnetic field (rotor RPM). Normally engineers take advantage of this last law to limit current to something safe for the stator. If they didn't and the magnets are too strong or they limited it at the raggedy edge of stator capacity, then higher average RPM's, current demand on the bike that pulls the voltage below 14.1, or a voltage regulator that intermittently shorts and pulls the voltage lower COULD cause stator failure.

It is difficult to imagine BMW getting the math wrong as the above principals have been in use well before BMW came into existence, but the failure rate would imply that at the leads, our stators are set up on the raggedy edge. What I find more likely is that the stator insulation or rotor magnets, or centering of the stator are NOT to design specifications. Or the housing is getting hotter then expected, oil isn't cooling as expected and this COULD change over time, or something in the oil is reacting to age stator insulation more then expected.

Yes, you could measure for shorts at the voltage regulator/rectifier and also see something called "partial discharges" of the stator which is the precursor of a hard stator short but you would need to measure on the AC side between the R/R and stator. The tool required would be a 3 phase harmonics analyzer or 3 or more channel scope with harmonics analytics. I have both cause I am an aficionado of fabulously expensive tools and an ex industrial electrician. It is doubtful that any others inside or outside the industry have such tools unless they are industrial electricians or design power engineers.

The copper does not age as long as the insulation remains intact. As iterated above, the insulation on all stators DOES age.

The primary cause of stator insulation failure is usually heat.
Poor insulation would certainly speed this up. Contamination in the oil or a bad batch of stator insulation would certainly be possible.
Vibration will cause stator failure ONLY if the stator was not dipped correctly. Tho whole stator is normally dipped in varnish, epoxy, or glass to prevent this type of failure.
Every stator I have seen has been too far gone to learn anything meaningful from.
There is also one more cause of failure that is not unheard of which is a 3rd harmonic induced failure. Essentially switching loads or noisy loads such as arc loads can induce a resonance of the 3rd harmonic and overheat the Y connection of the stator or add on delta legs. Its hard for me to imagine why a battery wouldn't buffer this or how it would get through the rectifier, but it's not my primary field of study and I may not know something. There have been semi credible reports of HID lighting causing stator failures and for that matter the fuel pump control module is a switching controller that could be implicated in this kind of failure but I'm out of my area of expertise in how these things would affect a stator behind a rectifier.

Also peak voltages will cause stator aging through something called "partial discharges". This is why I don't know if a series regulator is a good idea or not. Heat and PD will compete for causing the failure. An EE would need to answer this question and need a laboratory to do it as it could go either way. The stator may be aged very little by peak voltages or very fast. Depends on how well these stators are insulated from such and I have no idea.

There, a whole lot of typing with absolutely no definitive answers lol, but perhaps interesting reading?

Nope, at least I can not prove it and I have nothing heard from BMW so far. But I think it is legal to assume that they know about it. It seems sure that they know how many alternator warranty requests they have and we all know there are many. The big works always know what's going on and BMW claims to have very good service and customer relationship, at least over here in Europe.

It sounds logical to me, but I'm not convinced yet.

Mh... the only difference I know is that the Germans (compared to us Austrians and also to you guys) do a lot of high speed and even top speed riding on highways. Off road and on twisty back roads I dont think there's a big difference. But maybe you are right and it has to do with significantly higher ambient temperatures...

I think to isolate the problem its necessary to have some kind of matrix telling exact mileage when the stator failed, under which circumstances were the bikes mainly ridden (lots of low speed off road, highway use, commuting etc), what oil has be used, bash plates yes/know, additional electrical devices (lights, heated clothing, etc.)...

Not easy to find out....

BMW USA and BMW Germany ARE aware that some stators are failing earlier then they would like. I could swear to this under oath, though I wouldn't. I have no idea if they know the main reasons why. I do know no one I know does.

It is a problem they are aware of but just one of 5000 they are looking into.

I know its no consolation, but if you worked in the industry, you would have a different perspective.

Based on my past experiences, the morning conversation between an FSE and technical boss could go something like this:

Anything new FSE1? Yeah, I finally got through to the service manager at BMW X and had a talk about x's bike. They have no idea what they are doing, were gonna end up lemoning that. With franchises like this, who needs competition. What about the engine failures on the k16's anything further on that? Yeah, the guy in Florida died today but were no closer to why that engines exploding. Shit, nothing form germany yet? Who's the point guy there working this? xxx is but nothing new. Ok, He's good, hopefully we get something soon. We need to involve risk and get them up to speed and start start a conversation with NHTSA so were ready once we know whats going on. I want everybody ready to move on this one. Will do boss. FSE2, hows your area? It's going, I'm going to have to visit one of my dealers thats warranted about 100 ESA's in the past year. get warranty involved, have them draft up something friendly and scary on letterhead and mark it for principal only, then maybe that farmer cum service manager will listen Anything else? Read on a forum this morning that stators are failing early on the k7's. Oh my goodness, not a forum! What shall we do?? (general laughs around the room) Yeah yeah, we are starting to see an up tic, I know, warranty says were up to 12% in warranty. I forwarded it to Germany 6 months ago. Any thoughts to why they are failing when they are? Yeah, they suck, perhaps our german colleagues shouldn't have sourced a stator from an old yamaha a and figured it would bolt straight in. now now, they do hold the purse strings and remember, they build superior motorcycles (general laughs) I can't remember the name, but someone's working it there FSE3 speaks up "I got one in Cali that didn't burn all the way, want me to have him post it here? Nah, were spread too thin, I need you to get me answers on the K16 engine and work with x on homulgation of our new scooter. EPA hates anything fuel efficient that GM didn't make and there giving us grief any other bodies I need to know about?......

Above is totally fictitious, but every part of it I have heard while with one manufacture or another. We think about things in a vacuum on this forum. I know the USA guys are working a dozen problems that make the Stator look like nothing and Germany is working thousands. BMW USA has 4 field service engineers that report to one technical boss. Germany has less then a dozen engineers that are on motorcycles full time and have less then 10% of their time devoted to in warranty failures unless there are bodies attached.

In any case, they are probable contractually tied to this stator. God forbid it's not the stator. If for instance its heat from the exhaust. Well adding a heat shield will change emissions and likely increase NOX emissions an infinitesimal amount. Even an infinitesimal amount triggers a new round of emissions proving and homulgation which always costs 10's or hundreds of thousands.

As for disclosing the problem. Throughout time it has been proven that nothing good comes from disclosure till a working fix ix in place. Look at apple. The worlds largest electronics manufacture has built it's company on the bedrock of NEVER admitting a problem till it's fixed.

Frustrating to the knowledgeable user, but it's the way the world works.

@Joel

Joel, thanks for your long answer. Most appreciated. I admit that I did not get everything due to my limited abilities concerning the English language and especially the many abbreviations you use, but sure understood the most important things...so I got the essentials.

Long, long time ago I used to work for Chrysler and helped them settle the factory in Graz, Austria. I'm an engineer myself and I think your example is very true but has been "turned off" by the "forum vacuum" as you describe it. I did not see it that way, but it seems that it is how it goes as it was almost the same when discussing quality issues with Chrysler. Zillions of automatic transmissions died and the ynever said "hey we know its a poor design but we'll fix it!"
And like Aplle they fixed it (in this case an improved transmission oil cooler) and AFTER that they said "yep we had a LITTLE probem." This little problem affected 70% of all Chrysler Voyager vans sold on the German and Austrian market in the first two years.

So now that we have most probably uncovered what BMW does, or better NOT does, what will lead us to our target?

Tomorrow morning I'll try to reach an electrician I know. He once gave me an adress of a small shop who did alternator repairs. I want to see if they still do such repairs and I'd like to speak to them concerning the coating of the copper wire.

Thanks again,
Steve

That would be great! I have some abilities at analyzing stator failures but there are far better people out there. I will work a few of my old friends and see if I can find out what the stator is insulated with from the factory. I work for the competition now, but am not hostile to BMW so who knows, maybe I will get an answer. 2 of my friends have failed stators so this issue is personal to me.

Do the rewind shops have a way to rig up a test to see what temp we are looking at? Maybe an embedded RTD with leads coming out with the power leads? If you do this with a couple stators and install them you may get an idea what temps the stators have to live with.

David

I don't know if rewind shops do, but anyone could buy 2 digital cooking thermometers. Pull the guts out, pop the case off the engine and epoxy the thermistors to the winding. I'd do it but I don't have an F8 anymore.

Unfortunately the shop I tried to contact does not exist anymore but I try a few other things to maybe get more information about the wires and its insulation coating... may take a few days....

Steve

My 2009 F650GS's stator failed at 28,000 miles.

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I sent a picture of the stator-side of the bike to tech support at www.heatshieldproducts.com
and asked what they would recommend for reducing heat flow into the side cover/stator.
Here's the answer I got back:

WOW they sure didn't leave much room in there! I think the armor is the way to go, just cover the top half of the pipe with it, trim it down to fit. Unfortunately from looking at the application, I suspect you will have to unbolt the exhaust to get it in there good, but it should work. Just place the ceramic side (white side) touching the pipe, strap it down with some clamps, wire, or our Thermal-Ties, and away you go! If you only cover the top half of the pipes you will allow heat to escape out the bottom. If you try and wrap/completely cover that section of pipes, the spots on the exhaust pipe right before and after the wrap will become hotter.

you had the right idea with the HP shield, but the armor will be easier for you to work with, it works exactly the same as the HP shield, just easier to work with, and it will reduce more heat. Just use it to cover the top half of the pipe instead of wrapping around the whole thing.

These are the products he suggested:

HP Armor:
http://www.heatshieldproducts.com/productdetail/exhaust-insulation-and-wraps/heatshield-armor-exhaust-heat-shield/47/37<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
Ties:<o></o>
http://www.heatshieldproducts.com/productdetail/heatshield-tapes-and-stainless-ties/thermal_tie_stainless-steel-locking-tie/44/40<o></o>

Can anyone think of a reason that it would be a BAD idea to put a shield of this sort on the top side of the pipe?

A 1 foot x 2.5" wide piece would cover the top half of the upper pipe in front of and below the stator, you'd need three of the stainless ties - one for each end and one at the dog-leg in the middle I think...

The stuff comes in sizes much larger than we need, but I would be willing to buy a large sheet and a bag of ties and kit the stuff up for this application. I think it would cost $20 USD or less + shipping.

Unless someone talks me out of it, I'll likely do this .... PM me if you would want one of these kits.
I don't want to make this a "vendor" thread, and I'm really not in this to make a profit .... well not more than a 12-pack's worth of profit

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negative. I have only the standard plastic bashplate.

As Joel said this stator is interesting as it was only starting to fail.
The shop which rewinded it is closed this week for x-mas (hey , we are in Latin America. but as soon as they open I will go and stay there while they unwind it, and I'll take a few pictures.
but what is interesting to note is that the varnish is cracking only on the engine side (it appears there is more heat on that side). On the outside side, the wiring is only slightly discolored and only the 3 poles right behind the connection are black, as seen on the picture. I have no idea if the charred connection is the source of the problem (an elecric problem) or the consequence, (melted because in contact with the casing cover, which would be too hot).