Another alternator hits the dust and not under warranty

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

  1. JRWooden

    JRWooden Long timer

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    I a prior job, a long long time ago in a galaxy far away, when I mounted up thermocouples for temperature monitoring we used a "thermal epoxy" ... its a two-part expoy like the regular stuff, but modified for better thermal conductivity.... good stuff - this would likely be OK:

    http://www.newegg.com/Product/Product.aspx?Item=N82E16835100013

    Joel: You're right of course ... If we are going to get to the bottom of this .... getting some accurate baseline measurements, then comparing them to readings taking with bash plate, with heat shield, swapping regulators, etc. is really required.
  2. TheCowboy

    TheCowboy back in the saddle again

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    C5! I did not remove the headers. I got some heat wrap at the local auto parts store for $18.00. I used a couple of clamps to secure the tape at both ends. I started 1" forward of the foot peg and wrapped BOTH pipes all the way up just past where the Alternator cover stops, then single wrapped to finish at inlet.

    You MUST start your wrap from the bottom - if not you leave room for water, sand, ect to enter the wrap. You will understand what I mean if you start from the top...... hahahaha.

    I used a cheap-ass digital thermo. Yeh, I know they are not real accurate - I just wanted some kind of temp difference. I rode the bike for about 30 minutes without the tape - measured the alternator cover temp closest to the exhaust tube. Then I wrapped it, did a 100 mile hamburger ride and when I returned I measured at exact same place. It was much cooler... you could actually touch the cover without burning the hell out of your finger.

    So... my pea-brain says to me - "look, if the cover temperature is lowered, the stator temperature inside the cover must be lowered too" - and lower temperature COULD mean longer stator life". Really, it said that to me.

    Yes the stator area has a small oil bath. I would like to see a modified cover with some kind of cooling fins built in - because I REALLY think heat is the issue here...

    "I COULD BE WRONG - BUT I DON'T THINK SO" quote by Sir Charles Barkley...:D

    TheCowboy
  3. JoelWisman

    JoelWisman Long timer

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    Cowboy, by "cheap ass digital thermo" Do you mean something you have to press against the cover? Or one of the infra red jobs that you just point at it?

    If you used something that you have to place in contact with the cover to measure it, you used something far more accurate then the infra red units even if it was a toy :)

    If those measurements were made with a direct contact thermometer then I'm convinced you are onto something!

    I fully agree that the stator temperature is the most likely culprit.

    What I am having a hard time guessing is how much the cover temperature is affecting the temperature of the magnet wire.

    Only a lot of time or some serious measurements is going to tell.

    I'm a little leery about heat taping the header near the engine. At higher throttles as well as anytime the bike is running lean, the first foot of the header sees flame on the inside. Pushing hard I've hotter the first foot of my header glowing red many times.

    Insulating it may cause it to fail and could also increase the head temperature when the bike is pushed and especially when it's hot out.

    I don't see any issue with insulating the exhaust where it passes under the stator cover nor insulating the side of the cover.

    Fins on the outward facing portion of the cover would help as would using a thermally conductive substance to bond the stator to the cover.

    The part that is complex is the magnet wire is a major source of heat itself. Copper is very thermally conductive but it can still have localized hotspots. It only takes one tiny bit of the magnet wire overheating to cause a short that immediately overheats the rest of the phase and even adjacent phases.

    Since a failure anywhere in the magnet wire will cause a failure everywhere, and since the stator produces a tun of heat by itself, it could be that these stators are shorting where they face inward at the furthest place from the cover, perhaps somewhere they are getting little or no oil splash. Or perhaps they are failing in the closest place to the cover and heat conducted by the exhaust is the major contributor.

    I simply don't know, but anything that lowers the cover temperature sure as hell can't hurt and absolutely should help!

    If I still owned one of these bikes or still worked for a BMW dealer I'd be buying some digital candy thermometers, pulling them apart and measuring temperatures at a few places on the stator.

    Sadly I don't so all I can do is empathize from afar and enjoy the fact that both my current bikes are known for long life stators :)

    Good luck. I think you guys are on the right path and are bound to find it before BMW issues a fix, if they ever do.

    P.S. Cowboy, some of your posts are showing you to have anything but a "pee-brain", but riding 100 miles in Minnesota during winter for a burger is insane :p
  4. C5!

    C5! Been here awhile

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    Check Max parts catalog. It is the same part number for the alternator for the 800 S, ST and GS
  5. TheCowboy

    TheCowboy back in the saddle again

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    Joel, I am using a point-at-it IR Termometer from Radio Shack. I use it when I am troubleshooting aircraft engines - looking for a cold cylinder. Rather than the old way - putting your hand on each cylinder head cover and which ever cover does not leave flesh on it is the bad cylinder. Now I can just point and click and see which one is the coldest - indicating which cylinder is not firing.

    I can build an airplane from scratch (I've built three of them - all aerobatic hot rods), but I am only a shade-tree mechanic when it comes to motorcycles - all though I did work in a BSA shop all through my high-school years - I sure loved my 441 Victor - and I still have the scars on my shins to prove it.

    Like everyone else here, I am just guessing - shooting in the dark for some kind of answer to this puzzeling question of stator failures. I wish BMW would put one of there engineers on the problem.

    I'll let you know in another 50,000 miles if this heat tape fixed the problem - or sooner if it don't.

    TheCowboy
  6. JRWooden

    JRWooden Long timer

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    Thanks Cowboy .... :lol3


    I'd like to try other things, but I look in my toolbox and sometimes all I see is a hammer...
    Then I look at the problem and it doesn't seem much like it needs a nail.........................:lol3
  7. vtbob

    vtbob wanderer

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    It is clear that stator windings are being chared and failing. Fact one. The question is why and what the root cause is.

    Failures seem to come at 30,000 miles or more. Certainly not evenly distributed over time....ie the same rate of failures on new bikes and on the higher milage ones. Is this an important clue? Could this age related condition be fact two?

    A first though logically it that it is too hot. Why?
    Has the engine temp in the stator housing gone up over time? If so what would cause that?
    A lot of talk about exhaust pipe temp contributing. Are exhaust temps hotter on older bikes. Are the exhaust headers closer or touching the case? Not enough info on this but the ad hoc info seems there is no change here.
    Is there any real info to support the idea the stator housing gets hotter with the age of the bike? No?
    So if the stator housing is not hotter with age, what would cause the stator it self to get hotter with age?
    Is there more current flowing in "old" stators than new? If so what would cause this excess current?
    Are the magnets on the rotor getting stronger with age? Are they rotating closer to the stator...higher flux density so more current is made? An area to think more about.
    Could the regulator malfunction increase the currents in the stator? Most say no because of the design. Is that really true in all failure mods?
    Does the copper winding in the stator age? Would this aging cause over heating? No?
    Does the insulation on the stator winding age? Would this aging cause shorted windings and over heating? Would these shorts cause gradual output voltage reductions...that could be measured as a precursor symptom?
    Why would the stator insulation age / fail? Poor material used? Some type of contaminations? Vibration cause cracking? All good things to think about and get more info.
    Has anyone really analyzed a failed stator?
  8. JRWooden

    JRWooden Long timer

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    VTBob:

    All good questions .... If I were a gambler I woulf vote for the quoted item above... but it's just a guess.
    IMHO, yes, insulative qualities do degrate with time/heat so at some point when you get a short between ajacent windings the situation is agrivated and feeds on its self till it self destructs. The time it takes for this to happen would likely be a function of ambient temperature, average speed of bike (more convective cooling at higher speeds, but then also higher current in the stator at higher speeds ... not sure which would predominate.... ) and then if bash plate was installed this would reduce the convective cooling ....

    With the stator sitting inside the "counterbored" flywheel and not getting much of any oil bath cooling and sitting on top of the exhaus header it is a less than ideal situation for the stator....

    One of the other guys on the forum was going to send me his failed stator unit, but I have not hear back from him...
    If I get it I will try to see what I can figure out... but it may be difficult to figure out wether the insulative failure was the result of the failure or the cause of the failure or ... both ...?

    One thing I've mentioned before is that if the copper used in the windings is a lower grade it would have a higher bulk resistivity and thus create more heat.

    In terms of predicting failure ... if all three stator windings are at the same voltage (the voltage will vary with RPM) then likely the stator is good - if on the other hand one of the windings is at a lower voltage then likely that winding is failing ... A device could be designed that would plug in-line with the harness from the stator that would monitor/compare the voltages of the three windings and post an alarm if one winding started acting up.... In truth I'm not sure how much better that would be than just a simple voltage monitor...
  9. GB

    GB . Administrator

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    What about a regulator/rectifier that isn't running the stator at 100% capacity all the time. :dunno
  10. JRWooden

    JRWooden Long timer

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    Sorry to not be clear!
    IMHO a non-shunt type R/R (that did not run the stator flat out all the time) would reduce heating in the stator and thus reduce (eliminate?) stator failures.

    I was mostly trying to just respond to VTBob with regards to why the OEM design is failing prematurely ....
  11. GB

    GB . Administrator

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    If I had the technical know how, that's where I'd start.. Someone posted a link to an RR sold on Amazon.com An enterprising inmate could figure out a a plug and play kit to replace the stock RR and see if that runs the stator cooler.
  12. C5!

    C5! Been here awhile

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    I have purchased a Compufire regulator. When I receive it, along with a new stator (No. 4), I will install it and hopefully I will forget this nightmare. Meanwhile I will have the No.3 stator rewound and carry it as a spare on all long trips! :deal
    For general information, I have 45.000 km (less than 30.000 miles !!) on a 2009 model
  13. JRWooden

    JRWooden Long timer

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    C5!:

    Keep us posted! .......

    Two things I have read about the "series" style regulators
    1) They are less efficient at low speed than the shunt type
    and
    2) they could create more electrical noise in the system

    Let me be clear here :deal
    I'm not saying this is certain, I really don't know ... it's just what I've read here and there....
    I'd like to have more time to study this issue, it seems to crop up on other brands/models from time to time,
    so it's not just "us" :lol3
  14. C5!

    C5! Been here awhile

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    I dismantled the No.3 stator this morning. It appears that the "pole" which started to heat-up is the one at 180 degrees, the one right at the bottom. I don't know if it means anything, or if it gives credit to cowboy's assumption that there is too much heat coming from the exhaust, this is indeed the point closest to the exhaust.
    Stay tuned I will post pictures when I download them from the phone.
    In terms of data.
    the battery seems to have suffered from this 2000 km ride on battery...
    ignition off, 12.41 V
    ignition on, headlight on, not running, 11.95 V
    bike started, idle, 11.98 V

    Now the stator (No. 3)
    resistance between all 3 phases, almost zero
    resistance between ground and each phase, open circuit.

    Voltage output
    between Ground and
    phase 1: 1.06
    phase 2: 0.99
    phase 3: 0.6

    between phases, at idle
    1-2: 2.10
    2-3: 1.98
    1-3: 1.6
  15. C5!

    C5! Been here awhile

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    here is the stator still in its original location...

    Attached Files:

  16. C5!

    C5! Been here awhile

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    this is the "oil cooling" !!! 3 drops of oil at the bottom... is that an oil bath?
    ok th ebike is on its sidestand, if it would be vertical, would there be lot more oil?

    Attached Files:

  17. C5!

    C5! Been here awhile

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    somebody can give me a tip on how to open this connector?

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  18. JRWooden

    JRWooden Long timer

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    C5!:

    Neither the BMW nor the Haynes manual offer hints on releasing that connector...

    Question on the flywheel ... there seem to be two counterbored holes that are unused?
    Any idea why they are there?

    I don't think there is an oil bath ... only the wish that there was one........
    Some other engines use them, but ours alas does not as best I can tell ....
  19. JoelWisman

    JoelWisman Long timer

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    Merry Christmas all!

    The 2 holes are where the official BMW puller pushes. The rotor is a taper fit.

    Why oh why not a nozzle BMW. The crank is right behind that, hollow, and pressurized with oil. That said I don't fancy modding it. The big end bearings need oil too and I don't know how much if any surplus there is.

    There is a tiny tab on the connector, look where you wouldn't expect it to be and you will find it.

    No question from the picture, the stator is getting hotter towards the front of the motor.

    One issue I have with a series regulator is it wouldn't have helped me in the winter at all. They are a little less efficient at all RPM's cause there is more resistance for the current to pass through. A shunt type of regulator is pretty close to 100% efficient at full load. I used every amp the 400 watt alternator could produce for heated gear and lighting, so it wouldn't reduce load on the magnet wire at all for me, not on cold trips at least.

    I was already using high tech and expensive LED lighting and efficient heated gear and that was just one up. Two up I had to only heat my chest so G/F could heat hers as well.
  20. JRWooden

    JRWooden Long timer

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    Thanks Joel!

    Merry Christmas to you as well buddy!

    I'm looking around at exhaust pipe shields ....