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100% drive unit failure rate??
- Thread starter yobigd20
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- Driving Dynamics Model S
Could ceramic bearings be causing the problem? Ceramic bearings will not expand or contract with heat or cold. The metal surrounding the bearings will expand when hot or contract when cold and this could mess with tolerances, cause increased wear and lead to noise? IIRC Some older Audi engines had a similar issue. They used aluminum cylinder heads on steel engine blocks. Al and steel expand at different rates as the engine warmed up and this caused gaskets to fail.
How reliable are electric motors from other EV manufacturers? They don't make anywhere close to the power so motor reliability in the leaf and volt may not mean anything. GM for one does not use copper wingdings in their EV motors. They use copper rods pounded into slots to ensure they never get unwound.
How reliable are electric motors from other EV manufacturers? They don't make anywhere close to the power so motor reliability in the leaf and volt may not mean anything. GM for one does not use copper wingdings in their EV motors. They use copper rods pounded into slots to ensure they never get unwound.
stopcrazypp
Well-Known Member
The Roadster used a similar motor to the Model S, but didn't have the same issues. What changed?
For the Roadster, after two failed attempts at transaxle design (with two speeds), Tesla convinced Borg Warner (very experienced in transmission design and manufacture) to bail them out with a low volume (one speed) transaxle.
For the S, I think Tesla did the transaxle design in-house. I think that is what changed. It is likely that the transmission designers that Tesla hired did not have the collective knowledge that the B-W team did. Even with only one speed, gearbox design can be tricky.
Most drive unit issues are the "milling sound." One theory of failure that was posted here at TMC was that the bearings were not sized to handle the axial forces. This could be hard for Tesla to correct if there is not enough space in the housing for larger bearings.
Hopefully Tesla applied lessons learned on the S rwd drive unit to the new "D" front and rear drive units. Model 3 drive units will be a third generation of Tesla in-house design, and have potential to be a very good design.
GSP
For the S, I think Tesla did the transaxle design in-house. I think that is what changed. It is likely that the transmission designers that Tesla hired did not have the collective knowledge that the B-W team did. Even with only one speed, gearbox design can be tricky.
Most drive unit issues are the "milling sound." One theory of failure that was posted here at TMC was that the bearings were not sized to handle the axial forces. This could be hard for Tesla to correct if there is not enough space in the housing for larger bearings.
Hopefully Tesla applied lessons learned on the S rwd drive unit to the new "D" front and rear drive units. Model 3 drive units will be a third generation of Tesla in-house design, and have potential to be a very good design.
GSP
On top of the new transaxle, the Model S puts more stress on the drive assembly unit than the Roadster. The Roadster is a much lighter and smaller car, it takes less energy to get moving. It may be they didn't scale the bearings up from the Roadster well enough.
If the problem is stray currents going through the bearings, a fairly minor change mechanically could have opened up new current paths nobody was expecting.
Wait, are you suggesting that this might actually be a complex issue that's not easily solved by some completely disconnected participants on a forum? Please. Don't be ridiculous.
my bad, i was colorblinded--now i see it is a waterfall plot of frequencies.
Hey Yobig Dennis, Were you pulsing the throttle between accel/regen to cause the noise? What was the click toward the middle-- There seems to be a frequency spread before and after the click. 2900, 3700, 4900, 6100 Hz before, then 2900 and 3700 after. What was the speed or rpm during this run? Maybe we can determine some bearing frequencies from this data.
Hey Yobig Dennis, Were you pulsing the throttle between accel/regen to cause the noise? What was the click toward the middle-- There seems to be a frequency spread before and after the click. 2900, 3700, 4900, 6100 Hz before, then 2900 and 3700 after. What was the speed or rpm during this run? Maybe we can determine some bearing frequencies from this data.
mknox
Well-Known Member
Essentially, yes. The P cars have an inverter that can deliver more power to the motor. I had also heard that the P motors, while the same, had the coils hand wound or somehow manufactured to a higher tolerance.
Yea I was tapping the accel and then letting go several times. I did this to distinguish the milling sound going on and off in the analyzer. The tik toward the middle was probably something on the road or some junk in my car slipping. I don't remember lol. it had nothing to do with the issue at hand. Notice the date though if you go to the YouTube source. this was way back in 2013. This issue has been around a very long time. I was one of the first anyone had come across this issue. I had to go back to 3 different service center's before one of them admitted it was a problem. Since then it's pretty much commonplace they all know exactly what it is.
I wonder if my DU will be replaced. The inverter on my P85 is buzzing at low output (20-30KW) and it's loud enough to where I've had passengers mention it. They replaced my DU fairly early on when I mentioned the sound the inverter made under hard acceleration, but it didn't change (and everyone reported the same sound). In other words, they replaced it but I don't think it needed replacing. I'm at 34K miles on my car. The worst problems I've had were a bubble developing in the sidewall of one of my tires and the fuse blowing in my charger (early charger, they replaced the fuse). The other problems I've had were mostly annoyances, like rattles and squeaks which Tesla has been good about fixing. I frequently accelerate hard.
I suspect they'll replace my DU again since it's easier than replacing the inverter.
I suspect they'll replace my DU again since it's easier than replacing the inverter.
Sogorman
Member
The DU, or drive unit contains both the three phase induction motor and inverter. When The SC replaces a DU both the inverter and motor are replaced.
mknox
Well-Known Member
Sogorman
Member
Lon12
Member
http://cleantechnica.com/2015/11/05...ciency-3-tidbits-from-teslas-financials-call/
"An analyst from Credit Suisse asked about improvements on Tesla’s drive unit, from a bigger one it initially used to a newer small one. Expecting a boring answer, we got this from CEO Elon Musk instead: “Yeah, right now we’re actually very happy with the quality of the drive units. I mean, internally, our goal — we changed the goal of the drive unit endurance from being approximately 200,000 miles to being a million miles. Just basically, we want drive units that just never wear out. That’s our goal. And I think we’ve made really good progress in that direction.”Elon added that the drive units going out now are “excellent,” and then CTO JB Straubel chimed it by adding that they’ve made improvements to the large drive unit. The referenced issues, he said, were just in early drive units. “Today, we hold the same standard on both units that are being built,” he said. Elon got specific by stating that, “there was this one period of time we had … just before we transitioned into automatic grease injection into the spline of large drive unit, we had variation in how much grease was put into the spline, and if not enough grease was put into the spline, it would have premature wear…. But other than that, the large drive unit has been great. ” That getting technical enough for you?"
"An analyst from Credit Suisse asked about improvements on Tesla’s drive unit, from a bigger one it initially used to a newer small one. Expecting a boring answer, we got this from CEO Elon Musk instead: “Yeah, right now we’re actually very happy with the quality of the drive units. I mean, internally, our goal — we changed the goal of the drive unit endurance from being approximately 200,000 miles to being a million miles. Just basically, we want drive units that just never wear out. That’s our goal. And I think we’ve made really good progress in that direction.”Elon added that the drive units going out now are “excellent,” and then CTO JB Straubel chimed it by adding that they’ve made improvements to the large drive unit. The referenced issues, he said, were just in early drive units. “Today, we hold the same standard on both units that are being built,” he said. Elon got specific by stating that, “there was this one period of time we had … just before we transitioned into automatic grease injection into the spline of large drive unit, we had variation in how much grease was put into the spline, and if not enough grease was put into the spline, it would have premature wear…. But other than that, the large drive unit has been great. ” That getting technical enough for you?"
lolachampcar
Well-Known Member
Lon,
The really telling moment in Elon's response was when he said they were heading off in the weeds at one point in the drive unit development. Sure, they touched on a couple of points for which they have answers but it is clear to me that there is a lot more going on and they are not talking about it (understandable if you do not have answers).
The really telling moment in Elon's response was when he said they were heading off in the weeds at one point in the drive unit development. Sure, they touched on a couple of points for which they have answers but it is clear to me that there is a lot more going on and they are not talking about it (understandable if you do not have answers).
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