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Discussion in 'Model S' started by kenkamm, Sep 16, 2015.
Or is a high mileage driver!
My 2012 non-performance 85 just started the milling noise at 42,600 miles, at very low speeds. I thought I was imagining it, until my 11-year-old daughter said "Dad, this is the same noise that the Tesla Taxi in Amsterdam made!". Called in to Cleveland Service Center, hope it can be addressed before it becomes a more significant issue...right now it is fairly quiet, and hopefully doesn't pose any sort of mechanical threat.
I'm going to voice my appreciation for the way that the folks at the Rockville, MD Service Center have responded to me as well. I happen to have the electrical whine surfacing on my (replacement) DU as well, and they are in the process of getting another one ordered to swap it out. Their service has always been top-notch for me.
If, as the OP said, the issue is the call being made at Tesla HQ after hearing the recordings sent to them from the service center folks, then that may be where some of the problem lies. I sincerely hope that HQ recognizes that "getting progressively noisier" should not equate to "within spec", regardless of the mechanical performance of the unit... especially when we are talking yhids happening in many cases within a few 10's of thousands of miles...
 I deliberately am using this term, rather than "milling", as that implies a mechanical sound to me which I feel more strongly describes the bearing noise, which I had previously. This is an electrical power-delivery noise... as can be heard on other electrical devices with windings or high-power electronics.
The undersized bearing theory makes a ton of sense, but the much detuned Rav4 EV has the same problems. It's probably a bearing quality issue. Tesla started out with $ bearings which were crap, then they probably went to the next step which were $$, and so on. This is most likely another example where cheap becomes extremely expensive.
The fact is, I am the furthest thing from an aggressive driver. I never accelerate hard and just maintain an even flow with traffic. And mine is a non-P model. Yet I have the "milling sound" quite loudly and am waiting for my 3rd drive unit now. I'll defer to the experts here, but I still contend the sound seems "electrical" and not "mechanical" to me. I will definitely see if my Service Center can shed any light on the nature of the problem if/when they ever get me in.
I thought I read in one of the threads on the sound that someone was told the sound is essentially both. Basically, the bearing will, over time, get some slop and this in and of itself doesn't cause the noise. However, this now provides and avenue for an electric arc across the bearing and this is what is causing the sound. Overtime the electrical arc over the bearing could lead to an eventual mechanical failure of the bearing. In that thread, there was talk about how this should be a ceramic bearing to avoid the potential for the arc.
This makes no sense to me. No drive bearing should have current running through it in any case. It's not like there are lightning bolts shooting around in there and the bearing gets in the way. The motor has windings that are completely enclosed.
Makes no sense to me as I'm not an EE. In my post I quoted one of the posts where the conversation of it took place. If I interpreted wrong in that thread, forgive me. I would love for that other conversation to be explained to me so I can understand better.
I'm not a EE either, but I am a ME. Where did this bearing electrolysis data come from? I'd like to read more about it.
I can tell you that in designing a mechanical system, I certainly wouldn't design something that relied on electrical current flowing through a bearing, or even allow that scenario to occur in a failure mode. Of course it's impossible to predict every possible failure mode, so who knows what could be going on that Tesla didn't anticipate. But I'd like to know more about this electrolysis theory, if that's what it is.
If there is a specific cause, only Tesla knows and they are not letting anyone else in on it. It could be a cheap fix or it could be catastrophic. The only thing we know that's true is that two of their prior explanations were b.s. If I remember correctly, one was that it was a loose wire that simply needed to bracketed down and the other was that it just needed a 50 cent shim. If either were true, there would be no repeat failures.
Agreed. Elon said this during an earnings call. None of my issues were related to anything being loose, and my service center even said that the droning noise is a bearing issue. This was long before the milling noise appeared. At least with all three of my DU replacements, none were for the reasons Elon mentioned in that earnings call. I, too, don't believe Elon's statements regarding this issue.
Follow the link in supratachophobia's post I quoted to that thread and see the conversation around his/her post.
Am I blind? I don't see a link. But I did find the thread with a search, and the only mention of "electrolysis" was his, and he did not give a source. Did he make it up?
Low Speed, High Pitch Whine
When there is a quote, there is a blue "double-arrow" next to the person's name. That will take you to the actual post in whatever thread it came from. That is the link I was referring to.
So yes, I am blind!
FWIW, Tesla Service told me today that techs have been sent to training for how to open up a DU and fix the milling noise in the Service Center, though current practice may still be to replace with a remanufactured DU, and send the faulty/noisy unit back to be fixed, and then recycled as a reman unit. They assured me this does not pose an issue until it gets much noisier, and they are sending a Ranger out to record it the week after next (I am out of town next week).
Well, I could have been more clear on that too. I didn't notice the "Junior Member" flag on that, and I sure as heck didn't know that when I was a junior member not too long ago!
I think that someone once posted that the milling noise was caused by current getting in, and going through the rotor bearings, thus wearing them. This is probably where the current iteration of the story came from.
A bearing issue? Not good ... several years ago BMW Motorcycles Division installed a batch of faulty wheel bearings in the single-side swingarm of some of their models, which caused the rear wheel to begin to wobble over time and in some cases to come loose. One or two even caught fire, due to extreme friction. BMWs, and BMW riders, are STILL mocked for that in my motorcycle forum ... :biggrin:
I hope it was not due to somebody at Tesla pinching pennies in the wrong place, and buying bearings that "still met the qualifications" from the lowest bidder ...
Agreeing with your agreement as usual. I've heard the bearing noise is caused by un-anticipated electrolysis inside the motor that eats away the bearings over time.
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That effect is called electrolysis.