Another alternator hits the dust and not under warranty

Unfortunately, I agree it is unlikely we will get any public response. Eventually BMW will do some thing as this is costing them warrantee expense. The result will likely be a subtle change to the stator design and /or the regulator....likely evan still the same part number...just a mod/revision we will never know about.

So we are on our own. You have an impressive and expensive set of equipment (toys!). Well done!

I'll admit I have no clue at this point. My suspicion is either poor stator insulation materials that degrade and fail with age or poor stator design or materials so that the self limiting function of saturation occurs too late..ie too much self heating.

Insulation materials...I know of no way can find out what they are. ..to see if there is enough design margin to survive the worst case heat in operation and life of the engine. Our only hope is some replacement mfg or re winder will come up with a to better high temp retrofit part and sell it as say...a 550F certified part Some type of post mortum diagnosis may..just may give some insights...but that would be a science project.

Stator saturation yep a bit of a long shot. If we could determine/ find out the core material and the winding parameters we could come up with with some predictive saturation curves. This also could be tested with a new stator. One of the earlier posts did indicate current limiting. This would help predict eddy current heating. We already know that the heat dissipation environment in the installed engine is pretty poor.

Transient damage to regulator. due to diode effect of corroded connections or noisy/failing components is essential impossible for us to do. We can not replicate corrosion. dead end. We do not have a real schematic or part list so we do not know what type of on board filtering/decoupling is done in the regulator...nor do we know the main switching components...so can not determine either switching transient noise or susceptibility.
Putting your scope on a good bike and putting it on a failed or failing bike may...may give some in sites..ie looking into a black box....but another long shot science project.

I'm not a motor/ power guy so my knowledge is pretty ad hoc/ poor. Any one on this list have better ideas?

You don't like my idea?

post before yours ... no problem I'll get over it .... where's my

ooops didn't read far enough. my error

Yes it is a good idea.

I think characterizing the stator off a new 2012 f8 bike to a 2009 or so would be interesting....especially if there is a difference. i.e. have they done something different

Just funn'n

One thing that bothers me about the heat theories is wouldn't high mileage/hot climate bikes be failing at a much greater rate than everyone that gets cool to cold months?

Yeah, I would think high-mileage, hot climate, bash-plate equipted bikes would be failing faster........

We need to take a pole ............

Can we do that here? I know F800riders.com supports that................

Ok I received my new stator, Received also the new compufire regulator. If somebody can tell me how to post multiple pics in the same post I could document the new installation.

BTW in the manual they mention only sealant on the grommet, but not on the faces where goes the gasket, should there be sealant there?

BTW No. 2: anybody would have a spare grommet? that way I could prepare the old, rewound stator, as a spare.

C5!, where you buy your new stator and regulator?

I bought the stator from ElectroSport, the part no. is ESG070 and it is referenced for the F800ST. But as in the maxBMW parts catalog, it is the same part number for the GS and the ST !!
The stator came very well packaged and physically is the same diameter as the original but with a smaller width. The electrician shop told me that didn't made any difference.
On the left the new ElectroSport stator and on the right the old not yet rewinded stator


here on the right the new one and on the left the old one



But don't rush to buy that stator, because in the end it was defective, it lasted all but 5 minutes...
I am waiting for feedback from ElectroSport, I'll let you know.

edit: electroSport asked for the return of the stator for testing.

My 09 800GS failed at 69K and I think it started when we were in Alaska .
It developed a SLOW response when I rolled on the throttle Hard .
It failed me on a trip to Ca. right after Alaska. That would of been a nightmare up there .
Shop asked me " do you operate lot of electric's"
Why no sir I don't
Anyway all is good and having no other issues I think I can live with that.

As for the regulator it comes from Compufire. bought it on Amazon.
the unit is a bit different than the original one.

a bit longer footprint



and a bit thicker



So in order to install it, I had to extend a little bit the bracket. you see the original hole (the one in the middle, and the new one on the left, just solded a little piece of aluminum to extend it.



As for the thickness, it doesn't bother, it doesn't protude out of the frame.



you can also see the new exhaust wrap.

Now the whole process.
Started Saturday morning, first I wrapped the exhaust pipe, as suggested by Cowboy. It is cheap and can do no more problems than I already have.
Then I installed the new stator, welded all the connections to the plugs etc.. a job well done .
then continued with the new regulator.
Stated the engine and check the voltage. it started to act very erratically, going from 12 to 16 etc... I stopped the engine, reviewed all the connections, nothing wrong there, started again the engine and voltage constant at about 12, in fact wasn't charging at all. stopped the engine. worked in total for less than 5 minutes.
disconnected the alternator plug and read the voltage between the connectors and ground, 2 phases at about 18 V and 1 phase at 0. OKG not again !!!
went home to have a beer.

On Sunday morning went back to disassemble again the alternator. here is a pic of the "new" stator with only 2 out of 3 phases.



and for those interested, th eother side



Hopefully, I had the old stator rewinded, by the same guy in the same shop in Caracas. btw I asked if the insulation of the wire they are using would support peaks of 400V. They said no problem they are using that same wire in the big engine on the front working at 440V



In any case, I installed the old stator, started the engine, checked that we had voltages in all 3 phases, then connected the regulator, and voila, 14.2 V at the battery.
Did a little ride today and running fine.

Now emailed the people at electroSport this morning and waiting for their comments, and see what kind of warrenty they offer. Was the stator defective? was it not designed for that application?
ElectroSport asked for the unit for testing and possible refund

More laminations make for a more efficient stator (one on the right).
It reduces edy currents which do nothing but make heat, which I think we have all concluded is BAD
I showed this picture to an Electrical Engineer buddy of mine and he was astonished at how thick the laminations are in the BMW version.

Alas, if ElectroSport can't wind the thing properly it doesn't matter -- Hopefully the winding short-circuit was a one-off.

It would be interesting to measure stator temperature of OEM vs. ElectroSport with and without header wrap....

I wrap my exhaust too. But i still waiting for my rewinded stator

C5!, do you already had feedback from Electrosport?

good question, I'll email them. They should have received it by now. will let you know.

btw, you are in Portugal? I am going to Spain (andalucia) in March/april. bought an x-challenge to move around

Ok they did receive the stator, and are still making tests to see what went wrong.
they seem pretty professionals and issued me a refund right away.

Here is the copy of the email exchange:

I got your part back yesterday and I have given you a refund on it now. The stator was indeed bad when i received it.

Something you should be cautious of though is that high voltage you measured in the electrical system when it failed. The R/R should never allow over 14.7v into the system, and I know you mentioned you saw 18 volts. There could be a problem with your R/R that cause the stator to fail, I'm not sure of that, but it is possible. Be careful with your R/R and make sure it is not over charging your battery with your new stator, that would be a very expensive problem if left unchecked.

I have asked if the problem could be caused because the OEM is a delta wiring and theirs is a Y:

Yes I'm looking into the cause now. The delta vs Y winding would not be a direct cause of the failure. They can be used interchangeably without problem so long as the winding are done appropriately. There are some other differences too, but this item went bad because the copper we used was actually too nice. Long story short, we designed this part years and years ago and had it manufactured by another company to our spec based on testing and refinement of their samples. Recently we started manufacturing these ourselves, along with our entire stator line. When we do the manufacturing we use the highest grade copper wire available, much better then other stators uses. Problem is it turns out that the copper is so good there is a serious drop in resistance which leads to very high electrical output which damaged the stator. I will need to make a revision to the winding on the part and fix the problem, ill have a replacement part number for the BMW in a few weeks.

You could put it on the board, but I'm not sure if this is the cause of the problem. Your BMW stator is one of only a couple I have gotten back, but based on your description of the failure it could be the problem. I really need to further test the part before I can be sure of the cause, it may have just been a short in the stator, at the connector, flaw in the wiring harness, flywheel problem, lots of things. But I'm positive it didnt have to do with Y vs delta set up, as long as the stator is wound accordingly either configuration could be used for this application.

I already have mine rewinded and installed. The problem is that the who rewind it told me that he don't make it again because he don't like that kind of work.

Now if i need a new one i need to buy it. I wrap the exhaust to.

I ordered one of these. It should fit and work as a back up while I send mine out for rewind soon.

http://www.regulatorrectifier.com/catalog/2007-2011-BMW-F800S-F-800S-Stator

I will post later with fit results.