How long will our electric motors last?

How long will our electric motors last?

How long will Model S electric motors last?

I've heard bearings are suspect first.

Bearings are inside motor and connected to axle?

Inside the Tesla electric motor, what wears out?

I have been hunting an exploded view of a Tesla electric motor online.

jordanrichard | January 21, 2016

The only 2 wear points in the motor itself are the bearings. There are no other moving parts that touch each other. At one end of the rotor shaft is splined and goes into the gear reduction box. So I guess you could consider that wear point as part of the motor.

Elon has stated that in recent times, that the drive units as a whole would last 1,000,000 miles.

stevenmaifert | January 21, 2016

My drive unit as a whole lasted 20,000 miles before it had to be replaced last week.

jordanrichard | January 21, 2016

So your motor, gear reduction box and invertor all failed?

brandon.adams | January 21, 2016

I wonder if dual motor vehicles will be able to limp along to the service center with only a single motor operational. | January 21, 2016

In general, electric motors follow a bathtub curve--either they will fail early or last a long time. The lifespan of diesel electric locomotives is measured in decades. Only Tesla knows the MTBF of their drivetrain but electric motors are generally long-lived.

jordanrichard | January 21, 2016

Yes. In various interviews, one in particular with Bloomberg news, Elon said that in a way, having 2 motors allowed one to continue on, in the highly unlikely event that one of the motors fails.

stevenmaifert | January 21, 2016

@jordanrichard - No, but the drive unit is sealed. If one of the components fails, the whole unit gets replaced. In my case, the culprit was probably the inverter.

rxlawdude | January 21, 2016

@jordanrichard - Please don't spread inaccurate information.

It's well documented that a rear motor unit failure renders a dual motor vehicle undriveable. This is due to the HV line being daisy chained through the rear motor.

I don't think we've seen reports of front motor failure here or at TMC, so it's *POSSIBLE* that a front failure still allows the vehicle to move. | January 21, 2016

Almost all the drive replacements were for noise and not failures (although a few failures have occurred). I believe the noise problem was caused by the bearings having suffered unusual pitting over time due to the extreme magnetic fields. I think Tesla has switched to ceramic bearings, which are more expensive and similar to those used on the Roadster. Ceramic bearings don't have any issue with magnetic field pitting and should have an extremely long life.

I remember the quote from Elon as they are targeting for a 1,000,000 hour lifetime, but it is not clear what the current motors are achieving.

Anthony J. Parisio | January 21, 2016

Did your drive unite fail or was it just making noise? The replaces I have read about are do to noise not failure. Also they do not have to replace the whole drive unite. They can repair them. However they did not wish to inconvenience the customer. So they just replaced the hole unite. | January 21, 2016

For those that want to know more about the technical details of electrical bearing pitting issues (not specific to Tesla), this PDF does a great job:

Red Sage ca us | January 21, 2016

TeslaTap: I'm pretty sure that was "1,000,000 mile drivetrain" that Elon intimated as a goal. If it had been a million hours, then at 60 MPH, that would be 60,000,000 miles.

Google: elon musk million mile drivetrain | January 21, 2016

Thanks Red - you're right! | January 21, 2016

(but 60,000,000 miles would be really impressive!)

AmpedRealtor | January 21, 2016

One could argue that a failure is something that renders the vehicle inoperable. One could also argue that a failure is anything "out of spec" that would prompt a repair or replacement. I can see both sides. A noisy drive unit is just noisy, but it still functions in every other way. Is that a failure? Let's say your refrigerator starts making a terrible buzzing noise, but it still works in every other way. Would you consider that a failure? If not a failure, then what would you use to describe something like that? A fridge that stopped cooling would obviously be a failure, right, but maybe not just a noisy fridge?

I've had three DU replacements, all for noise. All exceeded Tesla's threshold for noise, so it would seem that they were "out of spec" in that regard. It doesn't much matter to me what we call it, what matters to me is that Tesla is stepping up to the plate and making things right for owners. Some DUs are being replaced without the owner even asking or complaining - Tesla is actually the one bringing it to the owner's attention. When does GM or the rest ever do that?

Even after 3 new DUs I have no worries whatsoever. If I've learned anything from owning a Tesla it's that Tesla will always "make it right" no matter what that is. They have the engineering skill and talent to overcome seemingly insurmountable problems. I know that Tesla has my back and that feeling is reinforced every time I visit my local service center.

I'm picking up my car from its annual service tomorrow, I'm going to bring the service center a batch of cupcakes as a thank-you for taking such good care of me. I never did that when I owned a Toyota.

tes-s | January 21, 2016

So far, so good.

flight505 | January 21, 2016

Wow, 3 DU's replaced? For which Model S?

Do the replaced DU's have anything to do with your driving style?

Do you floor the pedal for fast 0-60 MPH acceleration runs?

EdwardG.NO2CO2 | January 21, 2016

@Amped..."Tesla is actually the one bringing it to the owner's attention. When does GM or the rest ever do that?"

Actually the dealer does ,10 seconds after the warranty is up!

Silver2K | January 21, 2016

as per elon the replacements were done without proper diagnostics. some of the replacements just had loose wiring causing sounds and the DUs were being replaced wrongfully.

dnasserian | January 21, 2016

All moving parts CAN and WILL fail. Compared to an ICE vehicle, the Tesla's motor has very few moving parts that make contact and require little maintenance to prolong.

With an 8 year drivetrain warranty, why worry?

ran349 | January 21, 2016

@stevenmaifert- why do you think it was the inverter that failed? I would think that would be the least likely unit to fail. | January 21, 2016

@flight505 " - Wow, 3 DU's replaced?"

So far in 30K miles and 3 years no DUs replaced. I think you might have meant for your question to go to AmpedRealtor!

jordanrichard | January 21, 2016

rxlawdude, I am sorry about the inaccurate information. I got it from this guy in the clip at the :23 second mark. Obviously this guy is some low level within the Tesla organization.

stevenmaifert, no the drive units are not sealed. At about 35,000 miles my car developed the hum noise. My service said it was a bearing issue and they replaced the rotor which has the bearings pressed onto it.

Salute | January 21, 2016

The electric motor last a very long time. The electric motors put in the Snoqualmie falls power plant in 1899 are still working and are similar in architecture to the electric motor in the car. I would not be surprised if the old motors developed a humming sound back in 1910.

AmpedRealtor | January 22, 2016

LOL @ EdwardG.NO2CO2

@ flight505,

2013 P85. First DU replaced after 500 miles, 2nd DU at 8,500 miles, 3rd DU at 18,000 miles. Currently at just under 40,000 miles and so far so good. I've floored my accelerator pedal three times in 2 ½ years. I drive conservatively and my lifetime average is 295 Wh/mi. At least in my case it was not due to aggressive acceleration or driving.

Hart | January 22, 2016

For whatever it's worth, my rear motor failed (totally out), but car drove just fine with front motor last year. Less power, of course, but no problem getting from point A to B.

rxlawdude | January 22, 2016

@Hart - You're the first to report a rear motor failure in a "D" that still allowed you to limp along.

So there must be at least one rear motor failure mode that doesn't cripple the front motor.

stevenmaifert | January 22, 2016

@jordanrichard - I'll take your word for it, but the service rep told me the drive unit is sealed and they just replace the whole thing and send the old drive unit back to the factory. In my case the "noise" only appeared at highway speed, and only when power was being applied. If you let up on the accelerator the noise went away. The service rep said the noise was mostly likely coming from the inverter. Maybe he knew or maybe that was just speculation. As for how you define failure, it could be that something fails when it no longer performs to specs or it could be when that something quits working all together. Either way, I'm grateful that Tesla is warranty replacing these units at the first signs of abnormal behavior before we're left stranded by the side of the road.

flight505 | January 22, 2016
You are correct, sir - meant for question for AmpedRealtor, which he has answered.


Thanks for the info - single motor car, correct? And you have a light foot.

Makes me conjecture about durability of AWD versus RWD. Any thoughts?

I also believe electric motors have a long life due to their elegant construction.

AddysDaddy | January 22, 2016

For comparison, an ICE vehicle will typically need significant work to the engine and/or transmission somewhere around 250k miles.

As long as the Tesla motors last 250k miles, I presume that Tesla has an immediate advantage at that point since the ICE vehicle would've need far more work to support its' drivetrain and the Tesla motor swap is easy by comparison.

Elon has stated he's aiming for 1M mile motors, so you can presume 500k-1M miles is the upper bound on longevity.

jordanrichard | January 22, 2016

stevenmaifert, originally all drive unit related noise were resolved by swapping out the whole units and send them back to the factory. This was done for 2 reasons. One, it was the most expedient and two, service centers didn't have the know how to make repairs to the units. So, it is quite possible that due to the amount of business your service center gets, it might still be faster to just swap the units out.

The hum I was getting was in the mid to high 50's, whether I was accelerating or decelerating.

ra.cooper | October 31, 2016

My drive train failed completely in a scary gave me only 10 seconds of warning before the car stopped running. Had I been in a passing lane of Hwy. 75 or on the Skyway bridge, it could have been catastrophic with so much 70-80 mph traffic. There was not time/distance to pull over. Tesla replaced the DU, but my wife is fearful to take it on the highway. Mine is a 2013; 85S, with 34,000mi.

-Gman- | October 31, 2016

^ any symptom beforehand? unusual noise?
Did you ask what exactly failed in the DU?

carlk | October 31, 2016

I mentioned the ~60 mph hum that I noticed for a while to the SC when I took my VIN37xxx there for the first annual service in early 85'. They promptly replaced it after road test. It's really not that bad I could have accepted it if they told me it's normal. No other problems ever. I believe mine was around the time the DU issue we hear started to die down.

HbrwHmr | October 31, 2016

Does the drive unit warranty restart when they replace it? I had a water heater go once and the previous owner had already replaced it under warranty. The second one was not within the "original" warranty and they wouldn't replace it.

tes-s | October 31, 2016

No. The warranty is 8 years from original purchase date, and on some models limited to 100,000 miles.

jordanrichard | October 31, 2016

ra.cooper not to take away from your experience, but to categorize it as "drive train completely failed" would be the same as saying your drivetrain completely failed because the alternator on your Chevy died.

carlk | October 31, 2016

Even if you can describe it as a complete failure @ra.cooper's is still an extremely rare case for a DU. There were many cases in the early days of 12V battery or main contractor failure that one needs to stop and get a tow but not for DU as far as I can remember. Besides that for someone could be sacred so easily should never drive or ride in a car. It's not like we would never have a flat tire when driving 75 mph.

Sam_S | October 31, 2016

With the high volume and frequency of DU replacements due to the "milling noise", has Tesla ever officially communicated what the problem is attributed to and if the new DU's have overcome this problem?

Teslatap mentioned the ceramic bearing upgrade but is that a rumor or something Tesla has actually confirmed?

jordanrichard | October 31, 2016

A long while back, sorry don't remember specifically when, they improved the design of the drive units, with the goal of lasting 1 million miles and using ceramic bearings was part of the redesign. I don't believe Tesla ever officially stated this and I can see why they wouldn't. If they did, then every shall we say pre-redesign owner would be beating the door down at the service center demanding a new unit. I have a March 2014 built car, and at 36,000 miles, my DU was replaced for the milling noise which was very pronounced at a certain speed. My service center has the ability to just replace the bearings (cause of noise), but long story short, they just ended up replacing the whole DU. I was told that this was a brand new unit, versus refurbished, and was of the new design. I am now at 55,000 miles, no issues. Though of course, since the first motor's bearings were good for about 36,000 miles, I will be keeping an ear out for when I reach the 70-72,000 mile mark.

Captain_Zap | October 31, 2016

I thought this question was about motors.

Haggy | October 31, 2016

I don't think it comes down to what constitutes a failure, but to what failed rather than what was replaced. Tesla got a lot of bad press early on because of "drive train failures" that could have been classified as bearing wear, had Tesla chosen to keep cars in the shop for a week instead of getting the customer back on the road quickly with a complete drive train swap.

I do agree though that what constitutes "failure" is subjective. In my case, mine is noisy. My wife independently pointed out that the car is making an unusual noise, even though I had never mentioned my concern. Yesterday she wanted to use the car and asked me if it's safe to drive, and I get the feeling that had I not had a clue what it might be, and had it been her car alone, she might have left it in the garage and called for a tow truck.

Unfortunately, I'm not having much luck getting a response from Tesla. I did finally get a response from tech support saying they referred my issue to service, but service still hasn't contacted me. It's been a week since I contacted service using the online form and that was after never hearing back from a phone message.

SUN 2 DRV | October 31, 2016

To me a failure is when a device fails to perform it's main duty. eg a drive train that doesn't drive any more...

A drive train with Noise and Vibrations while it's still performing its main duty hasn't failed, but is operating at a suboptimal performance level. That's not a failure...

Just because something needs to be replaced to restore its full performance doesn't mean that it failed...

-Gman- | October 31, 2016

^ well if that's not splitting hairs, I don't know what is.

next summer when your air conditioner 'fails to operate at suboptimal performance levels" I'm sure you'll wait to have it checked before it completely 'fails'

-Gman- | October 31, 2016

... let's try that again... with less margarita...

Next summer when your air conditioner 'operates at suboptimal performance levels" I'm sure you'll wait to have it checked until it completely 'fails'

jordanrichard | October 31, 2016

AC not working at its best is not a failure, it typically means it needs servicing. Now, if the compressor seizes, that is a failure.

If one sparkplug fouled out on your old ICE car, did you consider that an ignition system failure? No. So when one part of the DU fails, doesn't mean the DU (motor, invertor, gear reduction box) failed.

-Gman- | October 31, 2016

^ Rubbish.
That's like saying "The Challenger didn't fail, it was just that one O-ring."
When something inside a DU stops working as designed, requiring service, that's a mechanical failure. (you can parse words about the exact component within the drive unit that actually failed, but to the owner, the drive unit is one sealed, inaccessible part, and Tesla has been replacing the whole part, so we say "that part failed and had to be replaced").

ra.cooper | November 1, 2016

@ Jordanrichard: My DU failure meant the car COMPLETELY stopped running within 10 seconds of the screen advisory to "Pull over immediately". Within the 10 sec. it was kaput; nothing; nada.. In Monty Python terms, "The parrot was dead". My advice to those with "milling noise" or any other strange noise is to take it to Tesla IMMEDIATELY...It's not safe to drive, in my opinion. Imagine your wife driving 75-80 mph and the damn thing quits in the passing lane--then what? I personally know 3 Tesla owners who have had it quit like mine did..and I don't know that many owners. Tesla said mine was the inverter, which failed-replaced by a "reconditioned" DU.

jordanrichard | November 1, 2016

It's not parsing words. When the Challenger blew up, or any other accident, they look for the failing component and conclude that is what failed and cause the subsequent accident. Would you say that your drivetrain (Engine, transmission, rear differential, half axels) failed because the transmission went out on you, leaving you on the side of the road. No, you would say that the tranny shit the bed. | November 1, 2016

@ra.cooper - The DU noise has nothing to do with outright failures. The noise is caused by micro-pitting of the bearings, and it appears you can drive with it for many years. The noise very slowly increases over time and is not a safety item or concern.

Clearly an outright DU failure where it doesn't run is a concern. I presume on your DU failure you had no prior notice. An inverter failure as you had will not produce any advance noise. Overall it seems DU failures where it stops running are far rarer than a blown engine on ICE cars (which may stop you very fast).