Another alternator hits the dust and not under warranty

Discussion in 'Parallel Universe' started by C5!, Jul 11, 2011.

  1. BMW_BIKER_KEITH

    BMW_BIKER_KEITH Been here awhile

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    Thanks for the data Joel. The saga continues.
  2. johngil

    johngil Reseda, CA

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    Just another item to keep an extra on hand with this bike...
    Going to need an extra shelf.:lol3
  3. RidingAgin

    RidingAgin Been here awhile

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    Interesting thread for sure.

    I worked at a fractional hp electric motor mgr 38 years ago, so the idea of winding copper wire around steel annealed laminations is not new. In looking at the photo I could not tell if there was an insulator between the windings and the metal. In making motors the stator metal was coated with epoxy for isolation. Edge thickness of this isolation was important as the windings were tested to assure a hi- pot test of 1800 volts.

    I was the reliability mgr for a while so we did testing of locking the rotor and life testing in it's application. Failure often occurred with a room of smoke with fried windings.

    I would imagine the designers did testing to assure that the design would be good but full load in a hot ambient with rock protection may not have been in the testing plan.

    In the case of some windings turning black seems a possible shorting to the laminations (gnd) should be investigated. That short would cause excessive current and heat IMO.

    One other rule of thumb was that organic finishes on windings life decreases by 1/2 for every 10 degrees C over 150 degrees C.

    :-D
  4. Steveman

    Steveman Been here awhile

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    Referring to Joels post #200 it seems the Bosch guy did tell me bullshit. :arg

    So considering that temperatures around 150 to 180° C (300-350F) would be still acceptable we can drop the idea of overheating due to high ambient temperatures in combination of heat radiaton of the exhaust pipes. I can not imagine that the rotor gets that hot just due to the mentioned reasons. What do you think? I mean if the engine is designed that way why is there obviously no cooling for the stator coil? Or does the oil cool the stator and we just dont know how it works (a schematic of the oil system could help)?

    I worked as car technician and then changed over to aircrafts so I know all kinds of engines and motors with pistons, rotary pistons and turbines. Oil temperatures in piston engines do not exceed 120°C (250F) under normal operation conditions. Measured at the correct measuring point, which is not the sump, drain plug or at the dipstick.

    As reported theres not much oil cooling the stator, right? No nozzels spraying oil at the stator and not enough oil in the engine housing that could cool the stator. Is this a poor desing or what is the idea behind? Why does BMW say use mineral oil (instead of synthetic)? Why is the F8 equipped with an oil/water heat exchanger (it is not an oil cooler, literally), its not high revving and it has a huge water cooler. There are bikes with more power and smaller radiators having no oil cooler....

    Strange.... and I have no clue what else we could try :(

    Steve
  5. JoelWisman

    JoelWisman Long timer

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    Ridingagin, All the cooked ones I saw with my own eyes had fully cocked, so I couldn't determine the primary failure point with my eyes.

    That said, it never has looked like a very quality stator. I say this with a grain of salt cause I'm educated in car alternators and industrial motors, not motorcycle stators.

    This however is my observation. The finish on the core is thin epoxy looking stuff with pretty sharp edges. There are no sleeves or insulators of any kind protecting the magnet wire from grounding on the core other then the thin epoxy like finish.

    Steveman, I wouldn't rule out ambient temperatures inside the case or of the case itself, nor oil cooling or the lack there of. The magnet wire itself generates a lot of heat. That heat leaves by convection, conduction, and radiation. The warmer the case, oil, and gases are, even though still bellow the maximum temperature the magnet wire insulation can take, the slower the magnet wire can shed heat through the above named dynamics.

    Also, for the types of insulation above, whats listed is the maximum RATED temperature. They SHOULD hold up to the maximum rated temperature for a considerable while, but not forever and NOT if they have any flaws or were at all damaged during the winding process. Its a non linear slope, how long they will take whatever temperature.

    In any case, winding a stator is always a flawed procedure that works because of "defense in depth" I'm sure the magnet wire is dipped more then once in the hopes that flaws won't line up and so its more resistant to abrasions, cracks, bubbles, and what have you. The core is epoxied and though not here, usually the channels are tubed or spaced to prevent grounds here.

    What I'm saying is it's not a matter of doing it right or wrong. It's never perfect and is rarely terrible, and every little thing helps to make the stator last longer.

    I don't know if these stators are dying from heat, voltage spikes, movement, solvent damage, heat shock, poor winding, overload, or what.

    Either way, it's no different then the guy that smokes like a chimney, drinks like a fish, stresses day in and day out and enjoys blow every weekend. Perhaps he will die of cancer, or maybe his cause of death will be a heart attack, but the real underlying causes were all of the above with age and heredity kicked in.

    No matter the ultimate cause of stator failure, improving any of the things that age stators will increase it's life. No stator lives forever, they will all die, we just want to make them live longer.
  6. Steveman

    Steveman Been here awhile

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    Well, ...assuming that BMW will not do anything to help finding an acceptable solution we then should reduce our efforts to find the cause(s) and put even more effort into reducing the stator coils temperature, meaning all following points could (and most likely will) reduce stator temperature, thus extending its life cycle

    .) reduce exhaust tubes temperature (heat shield, heat wrap, coating etc.)
    .) reduce engine temperature (different thermostat, bigger waterpump rotor, free airflow to radiator)
    .) use different regulator (compu-fire may work)
    .) use stator from Camro or other brand or rework existing one
    .) reduce maximum alternator power
    .) improve contact surface between stator coil and engine cover

    anything else? By the way has anyone done the regulator mod?

    Steve
  7. ragtoplvr

    ragtoplvr Long timer

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    on harley stators 180C did not last, 200 did better, they also tend to fail after 30 K miles

    Rod
  8. JRWooden

    JRWooden Long timer

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    The oil level is above the bottom of the flywheel right?
    If so ... perhaps several small holes drilled thru the flywheel at an angle of attack such that they would "push" oil into the interior where the stator is located? You'd want to avoid drilling through the magnets which might not be possible....
    I'm sure I'm doing a crappy job of explaining what I'm thinking......... :lol3

    Maybe this will need a picture...........
  9. vtbob

    vtbob wanderer

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    It seems to me we still do not know the real root cause of these failures.

    While there have been several bandaid ideas ..like wrapping the exhaust pipes, using aftermarket bits to cut the power output in half...and the associated heat, etc etc. These all likely help some what....but many of us will still have premature failures that are very expensive.

    We need the BMW designers, who truly know the electrical design parameters,of the regulator, stator and armature, the environmental conditions within the engine to step up and diagnose this problem....and share that info with their dealers and customers.

    Let the chips fall were they may..but then we will know the best way to a real fix.

    This blog, and others are interesting, but after a couple of years now still have not led to proper solution.

    Is it time we sent letter to BMW? something else?
  10. JRWooden

    JRWooden Long timer

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    I was going to make some snide comment about threatening the Germans with having to financially support the Greeks and Italians for all eternity ... if they don't fix this problem but maybe I'll pass on that and stay on topic ... :lol3

    Probably step one trying to get someone's attention would be to collect a list failed stators with along wiith some statistics like miles on the bike, typical riding conditions (hot cold lots of electrical load or not... etc.) amount of time the bike has been in service VIN number owner's name/contact data in/out of warranty etc. I we had those statistics, the list was long, and mileage figures were as short as they seem to be then ... maybe we could get some action? :deal

    Otherwise I don't think the conversation would go very well.............
  11. MoToad

    MoToad Been here awhile

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    Well, this one's certainly got my interest peaked. Altho my problems are "apparently" fixed as mine failed around 50000 and just inside of my warranty time. I posted it somewhere but cant remember. Thing is, Rick, my mechanic is an old timer with a lot of previous experience on Ducs and he said stators were always failing back ten or twenty years ago. He had no offering of why the Beemers' are failing but did what they used to do with the Ducatis. Which is, ground the regulator with an extra wire. Said it fixed the Duc problem. Don't know if it's going to fix future failures for me or not and with heat more likely than not seeming to be a contributing factor, I'll be looking into the wrap myself. As for the bashplate being a contributing factor, a big portion of the failures have been S models, haven't they? The road bike? Doesn't have a bash plate does it?
  12. TheCowboy

    TheCowboy back in the saddle again

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    It would be interesting to find out how many of the lower time failures had bash plates installed. My stator did not fail until I had accumulated 50,000 miles. I do not have a bash plate - so unrestricted flow across the pipes.

    TheCowboy
  13. vtbob

    vtbob wanderer

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    After reading all these posts and looking at a couple of other blogs Aprillia, rotax, Denso. I've come to the opinion...I stess opinion..that ambient engine heat, exhaust headers, skid plates etc have no effect on this failure.

    The Aprillia fix seems to be a second ground on the regulator...implying if the regulator ground degraded it cause the stator to over heat.

    Some stator failures show only a few coils are over heated, other show the whole stator over heated.

    All this seems to indicate an age related failure of the charging system which manifests itself as stator failure.

    Sure wish BMW/Rotax/Denso would speak up on this and put the speculation and all the wasted effort to a end.
  14. Cesar Serpa

    Cesar Serpa Adventurer

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    Mine only have 20000km and a stator burned. I don't know wen really happened i bought it two months ago but i can not prove it already damaged but now i need to resolve this problem. I send the stator to rewind but after that i read where i am afraid that will happen again soon :( One thing is true the exhaust pipe near the motor is not good, so i´m thinking to use the heat-shield in the exhaust. JRWodden do you already order it?
  15. JRWooden

    JRWooden Long timer

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    I have not ordered it yet ... to get the price down I have to order in bulk and need 10 guys or so to make it work...
    The kit would be a piece of the insulating material 12" x 3" x 1/4" thick and four "zip ties" made from stainless steel.
    Right now I only have 4 guys interested....

    Cushman
    GB
    FredRyder
    me

    Let me just say going in to this, that I am reasonably sure that the header heat is not the "root cause" of our problem, but the added heat can not be a good thing ... it seems to me that for $20 it's a good idea in any event...

    I have two questions for guys with failed stators:

    1) were the fried windings at the bottom?

    2) have you removed your R/R and inspected for solid (electrical) ground contact?
    2b) If you have not done so, would you take a look and tell us what you find?

    Thanks,
    Jim
  16. JRWooden

    JRWooden Long timer

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    VTBob:
    I just took my R/R off the bike.... I'm stunned ........... :huh
    If there is supposed to be a ground ground connection from the frame of the bike to the regulatore ...
    It sucks ... sucks real bad...

    Let me count the ways:

    1) the heatsink shell of the regulator is anodized (?) or otherwise passivated...
    anodizing does not conduct eletricity well, so I hope it's something else...
    anyway... it's a less than ideal "contact interface"

    2) there are a pair of thick washers between the back of the regulator and the bracket
    I'm not sure why they are there ... they are not mentioned in the Rev. 4 BMW manual...
    Maybe for better heat disappaiton....
    Anyway... add two more contact "interfaces" ... they are steel washers and conduct OK,
    but ... add two more "contact interfaces"

    3) The screws holding down the R/R + washers do NOT screw into threaded holes in the bracket,
    rather there are two tinnerman clips on the backet and the bracket is painted.
    No special preparation seems to have been done (masked off spot on bracket ...)
    to enhance electrical conductivity... this is a very crappy "contact interface"

    4) The bracket is bolted to the frame with two more screws and guess what ....
    No special preparation seems to have been done (masked off spot on bracket ...)
    to enhance electrical conductivity... this is a very crappy "contact interface"

    Are we SURE that grounding is supposed to be done through the frame of the regulator???
    Because if it is... well this is a serious issue...........
    I'm going to go find the wiring diagram................
  17. ebrabaek

    ebrabaek Long timer

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  18. GB

    GB . Administrator

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    Use a multimeter from the battery's negative post to the R/R and see if you get a reading or not. If you do, then my guess it's well grounded.. maybe :D
  19. JRWooden

    JRWooden Long timer

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    The BMW manual offers no schematic that I can find ...
    The Haynes manual has a schematic and it does not call out a ground from the frame of the regulator to the frame of the bike...
    it only shows that pin #4 (brown) goes back to the negative terminal of the battery............

    I can assure that the ground from the frame of the regulator is crappy.............
    but maybe that's because it's not needed? :huh
    If it is required ... somebody in Germany needs to be shot... then hung..........
  20. MoToad

    MoToad Been here awhile

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    One thing my mech did stress was the stripping off of the non conducting anodized surface to get a good ground.