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CarlK
Active Member
Well how could you have missed the title that the comment was under?
A Short Seller’s Comments
I sent my write-up to a friend who is short Tesla’s stock and he shared some comments:
A Short Seller’s Comments
I sent my write-up to a friend who is short Tesla’s stock and he shared some comments:
The article is stupid. ...A short seller's comments, indeed. But I guess it got everyone talking.
FWIW, I'm an engineer too... And I can say that regardless of how much of an "expert" someone is, there are just too many factors to consider and unknowns to explore for something like this. The drive motor with cut-away section on display at my local Tesla showroom looks cleanly built and designed well. I can think of certain things that might make it better, maybe. But we don't know unless different prototypes can be assembled, rigorously tested and all that. I'm an engineer, but I'm in no way an EV expert... I know a lot more about bridges and buildings and software development... I know that Tesla has spent a lot of man hours and other resources on developing these cars and the Model S has been an absolutely great car. Yes, some problems, even with the drive motors, but still a great car. I'm not saying they got it right or made the best motor possible, I'm sure we'll see continuous improvements from them on the motors as time goes on.
Now, while we're on the subject of being an armchair EV engineer, I recently watched one of the How It's Made shows or one like it on the Science channel that discussed another high-dollar electric offering. By comparison to Tesla's motor, the one used there was rather crude in construction with sloppily-hand-wound wiring dipped in resin and I saw nothing about it that impressed me in any way, nor was it designed or built in a way that I would even consider, unless it were a go-kart project in my own garage. ...all seemed like big money wasted to me.
FWIW, I'm an engineer too... And I can say that regardless of how much of an "expert" someone is, there are just too many factors to consider and unknowns to explore for something like this. The drive motor with cut-away section on display at my local Tesla showroom looks cleanly built and designed well. I can think of certain things that might make it better, maybe. But we don't know unless different prototypes can be assembled, rigorously tested and all that. I'm an engineer, but I'm in no way an EV expert... I know a lot more about bridges and buildings and software development... I know that Tesla has spent a lot of man hours and other resources on developing these cars and the Model S has been an absolutely great car. Yes, some problems, even with the drive motors, but still a great car. I'm not saying they got it right or made the best motor possible, I'm sure we'll see continuous improvements from them on the motors as time goes on.
Now, while we're on the subject of being an armchair EV engineer, I recently watched one of the How It's Made shows or one like it on the Science channel that discussed another high-dollar electric offering. By comparison to Tesla's motor, the one used there was rather crude in construction with sloppily-hand-wound wiring dipped in resin and I saw nothing about it that impressed me in any way, nor was it designed or built in a way that I would even consider, unless it were a go-kart project in my own garage. ...all seemed like big money wasted to me.
Would someone mind explaining the difference between the "Drive Unit" (DU) and the Motor?
(or point me to a thread?)
I've seen a bunch of people say on various threads that they need a new DU. Some folks are on their 2nd or 3rd one.
I even searched once to see what the price of a DU replacement would be (in case I ever decided to buy a used MS with not much warranty left).
I always took DU to mean the whole motor thingy. I am an electrical engineer by the way. Sorry for the technical term "thingy"...
But as I understand, there's only one speed (i.e. no traditional transmission), so if the DU isn't the Motor...then what's left other than
the shafts (with possibly some joints?) that go from the motor to the wheels?
...And if it's not the Motor...why does it cost so much? (like $10-$20k IIRC)
At this point, as far as motor tech goes, we have Tesla's AC inductor motor vs Bolt's permanent magnet type. There's probably not much innovation going on beyond technology choice (cooling is the area needing improvement but not likely to be the cause of failures). As it appears, most Tesla DU failures were due to gears wearing out (not actual motor failure). Therefore I expect gearing to be new and improved in upcoming model 3.
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I've owned two Teslas (P85 and currently a P85D) and while I'm sympathetic to those who think that Tesla, the stock, has issues, my experience says that Tesla's design and production are top notch. I drive cars hard and I make more than ample use of Insane mode...other than some weird goo leaking out of the frunk in my P85, I've never had a mechanical issue with either of my cars, and this is over a combined 50,000+ miles of hard driving. I can't say the same for any of my ICE vehicles, other than one (the Ford F-150 with a 5.4 V8, which has been absolutely bulletproof). I had engine issues with my Audis, with my Mercedes, with my BMWs, with my VW, even with my Lexus (and don't get me started on the non-stop problems I had with a Dodge pickup circa 2000). None of the issues were catastrophic, but they were annoying and, at times, expensive (see, e.g., the carbon build up in the supercharged Audi engines).
Maybe I've been lucky with the Teslas, but mechanically, they rank in the top tier for reliability and function of all the vehicles I've owned.
Maybe I've been lucky with the Teslas, but mechanically, they rank in the top tier for reliability and function of all the vehicles I've owned.
CarlK
Active Member
There is nothing really that special about making a motor. Industrial AC motors are all rated 10 years or more service life with continuous operation. Even my cheap ~$80 Chinese made fish pond water pump motor has been running 24 hrs everyday for years.
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My Model S P85 (Vin x6817, I believe) has over 75000 miles on it. We did get a new DU because of the wearing out of a gear component and that, along with an initial problem with the handles, has been the only major problem the car has had.
The Tesla motor is basically a 100+ year old design and works well, so the only possible problem is the execution of that design. As another poster said, the wiring looks to be very cleanly and professionally done. Watching a recent behind the scenes video showing the motor being built at the plant, it seems to be quite well built - but as another poster said, there are just too many variables for anyone not directly testing the unit to tell.
FWIW, I'm an electrical engineer and physicist and have built similar (not nearly as powerful or professional) motors in the past.
Jason
The Tesla motor is basically a 100+ year old design and works well, so the only possible problem is the execution of that design. As another poster said, the wiring looks to be very cleanly and professionally done. Watching a recent behind the scenes video showing the motor being built at the plant, it seems to be quite well built - but as another poster said, there are just too many variables for anyone not directly testing the unit to tell.
FWIW, I'm an electrical engineer and physicist and have built similar (not nearly as powerful or professional) motors in the past.
Jason
Ummmm....errrrr. Do those 6 words alone not kinda backup the "motors are dodgy" camp rather than the other way around?
Just sayin. I am sure you like the car - but you did need a new drive unit!!!
I know they have an 8 year warranty but I would personally now be nervous about buying a 6 year old Tesla for example in a couple of years time as I am guessing a "new DU" could be expensive.
Erleichda
Member
Search the forums for the DU discussions to see images of the original gear/diff and the newer ones...way beefier. They have had quite a few versions and designs over the years addressing this as well.
Fanatic1
Member
aesculus
Still Trying to Figure This All Out
It would be fine if the could state exactly why the engineering, design, materials, assembly or whatever the 'subpar' was caused by. They they would have some cred. And BTW they would have to have an expert in any of those areas or related field to actually be able to state that. Not the thing is just junk without being specific and calling out exactly what is likely to fail and why.
ratsbew
Active Member
Ugh. With the stock price inching higher, the shorts know they stand to lose lots of money. They are putting out these lie pieces in an attempt to drop the stock. I can't wait for the Model 3 announcement to shoot he stock above 250 again so these loser can be out lots of money.
I'm an engineer too, Electronic Engineer in my case. As far as engineering for motors goes, there isn't all that much new under the sun, however an old technology executed well or badly. Getting things from China can run the gamut from close to the best in the world to dangerously bad (mostly due to counterfeits), it all depends on how much time and effort and quality of materials the company making them wants to put into it.
One thing I have observed is Tesla packs the drive system for their cars much tighter than any other car out there. Hybrids are going to have more inside that pure EVs, but the Leaf, Bolt, and i3 all seem to be much busier under the "hood" than Teslas, though the Model S and X are much larger cars than any other BEV, they also have much more output from the motors than other BEVs too. One thing I haven't been able to determine for sure is whether the better use of space is an illusion due to being a bigger car, Tesla just packaged the whole thing better than anyone else, or Tesla is getting a lot more out of smaller motors than the competition. Or some kind of mix of all three.
If Tesla is getting more out of smaller motors, there could be a long term reliability problem lurking there. Smaller parts put under more stress are just going to have shorter lives most of the time. It's one of those engineering trade offs you have to factor in.
However out in the real world, we have little hard data to look at because even though there are cars with more than 100,000 miles, virtually none of those have original drive units. Very few people have had catastrophic drive unit failures, most replacements have been due to abnormal noises (which might lead to dead on the road failures if it was left to continue, or it may not). Most stories of people who have been stranded had to do with some kind of electrical failure, usually battery related.
I am kind of skeptical of the urban legend nature of this story: "I heard from this guy..." There are some people who are tearing apart junked Model Ss and learning what makes it tick. wk057 here on this forum is one of them. There is a YouTube video from a guy in Germany who got the drive unit from a Mercedes with a Tesla drive train working on a bench. Though I don't know of anyone who has done a thorough analysis of the motors and published any kind of report on the quality. Until someone is willing to publish and put their name on it as well as provide the data that led to their conclusion, I'm going to take these types of stories with a grain of salt.
I am not sure why we are spending any cycles debating that trolls comments. I am sure he is reading this topic and is having a good chuckle. He is a well known Tesla hater who is keen on seeing this company fail so that he can big bucks on shorting the stock. He is well known to make up some outlandish allegations in his seeking alpha articles.
