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Will AWD motors last longer than RWD motor?

Will AWD motors last longer than RWD motor?

Anyone has experience, read or heard ot a different longevity between a Model S AWD or RWD motors durability?
With the bigger rear motor going to idle while cruising on the highway with the front doing the work, is it expected to have longer lifespan than single motor RWD?

brando | 13. März 2017

Elon claims his design goal is for Million miles for the motor.
(He didn't make exception for RWD or AWD.)
I doubt you will own this car long enough to matter.
At 20,000 miles/year it will take 50 years.
If new, you get an 8 year unlimited mileage warranty. Why worry?

brando | 13. März 2017

Elon claims his design goal is for Million miles for the motor.
(He didn't make exception for RWD or AWD.)
I doubt you will own this car long enough to matter.
At 20,000 miles/year it will take 50 years.
If new, you get an 8 year unlimited mileage warranty. Why worry?

vp09 | 13. März 2017

Brando, Now you have me wondering.

I chose the AWD because it was more advanced, better MGPe, better regen capability, but you bring up the durability issue now. What is your thinking on this?

CraigW | 14. März 2017

The Tesla was the best selling car in Norway before they introduced AWD. If the RWD can do well in the snows of Norway, I suspect we don't have to worry about most places in the U.S.

Aside from tire ware and road adhesion - and these don't impact the motor - I really can't see the difference in durability based on the number of motors. Perhaps if the design was like ICE 4-wheelers that might impact the suspension differently, but it would seem this question illustrates more about lack of knowledge of an EV than a potentially serious issue.

topher | 14. März 2017

It seems unlikely to me that any reduced load on the motors from having two of them, would affect the MTBF by more than a small percentage. On the other hand having two, halves the MTBF for the whole thing. Electric motors have pretty long MTBF, so it may not ever be an issue.

Thank you kindly.

Haggy | 14. März 2017

For the motor assembly itself, there's nothing to wear out based on friction, except for the bearings which aren't likely to wear out. With the earlier motors, the bearing design wasn't good, and Tesla changed it. I'm sure the Model 3 won't start out with inferior parts and change to better ones when Tesla has already figured out that problem.

High power industrial motors that are designed to be left on 24 hours a day can run for a decade. If you translate that to rotations and compare it to how much a car motor spins over the course of a million miles, it's not unreasonable to expect Tesla's motors to last that long, but even if they don't, they will be cheaper to repair than car engines and should last many times longer.

Frank99 | 14. März 2017

Fully agree, Haggy.

As I understand it, the problem with the bearings in the early Model S motors had do with unexpected electrical currents flowing through the bearings, rather than inferior parts. It's apparently become much more common as large AC motors get driven with variable-frequency electronic controllers (sound familiar?). A paper from a vendor has a good description:
www.est-aegis com/TechPaper.pdf

Badbot | 14. März 2017

With conventional motors the current does cause wear.
Lucky for us tesla uses induction motors which have no brushes or armatures being worn.
The strength of the fields actually had stray arcing through the bearings that pitted them.
The new bearings are ceramic that do not conduct like the steel ones did before.
the motors now should run until the bearings exceed the service life but they should be serviceable.
assuming that the load would wear the motors then splitting the load between 2 motors would lessen that load. I know Elon is an engineer and believe him that the motor or motors will go 1,000,000 miles. I will never drive enough to test this so I can let it go.
I have worked on a few million mile big rigs and they got that many miles only after being rebuilt a few times.

If anyone try's to tell me that the motors will not outlast an ICE I know that they are FUD merchants.

dave.m.mcdonough | 15. März 2017

"With the bigger rear motor going to idle while cruising on the highway with the front doing the work, is it expected to have longer lifespan than single motor RWD?"

Nope. As the torque output increases it might load the bearings a little more, but really it'll be 99% the same life if it's 0% loaded or 100% loaded. There's also a magnetic load on the windings themselves but that's easily potted because it's not a moving part. Nothing like ICE engine with crank bearings, sleeves, all sorts of mechanical things that get stressed.

Also I was under the impression the rear motor is the same size either way.

JHB10 | 16. März 2017

Power electronics do "wear" if heated, as the junction between the p an n materials shifts.
So if the two motors run with half the current per motor, and the result is a significant temperature difference on the electronics, those units should last longer.

brando | 01. April 2017

Easy to forget that advances are happening in most fields. This includes material science (metal alloys for example). Try to learn how many alloys of Aluminium they have created. side note: The largest use of Lithium used to be for aircraft. Lithium both increase the strength AND decrease the weight (of course SpaceX uses on it's rockets). Now I suspect batteries are or will soon be the largest use of Lithium.

Anyway, check out this million mile Saab 900
http://www.saabplanet.com/1989-saab-900-spg-with-1-million-mile-donated-...

back to Lithium
Lithium and its compounds have several industrial applications, including heat-resistant glass and ceramics, lithium grease lubricants, flux additives for iron, steel and aluminium production, lithium batteries, and lithium-ion batteries. These uses consume more than three quarters of lithium production.

of course google will help you find much more info

Efontana | 02. April 2017

If it is straight wear out "lifespan" dual should last longer. But failure rate is the bottom of the bathtub curve. But that is different.