Drive motor durability

Drive motor durability

I've been researching the durability of the Tesla electric drive motor but couldn't find any information. Does anyone know or have any idea, in terms of how many miles, is the electric motor rated at? A typical ICE motor I think is rated at 100K - 200K miles, maybe more? | 16 juli 2014

Tesla has stated it should last the life of the car. AC induction motors only have one moving part, and their use in industrial applications have shown them to be very durable.

They are not under the extreme heat, friction and pressures you encounter with ICE engines that require continuous maintenance to keep them going.

info | 16 juli 2014

AC induction motors have been used in industry for a long time. They are installed, turned on and run 24/7 for many years afterwards. Shouldn't be am issue.

johnl972001 | 16 juli 2014

I'm wondering if the constant acceleration/deceleration, start/stop, etc. have any negative affect on AC induction motors.

jordanrichard | 16 juli 2014

I have never heard of an engine being "rated" for a given amount of miles.

What does wear out in an ICE is the compression and oil rings on the pistons, and the valve train. Since the MS doesn't have any of that, there really isn't anything to wear out.

LEvans | 16 juli 2014

Some have had these units replaced and it is understandable that some may go bad but I think they need to be able to take it apart and fix or replace the individual main components rather than necessitating the $15K repair bill to replace the entire drive unit that a form member recently had to pay because his car was out of warranty.

dramingly | 16 juli 2014

Has the MS been out long enough that any cars should be out of the standard 4 year warranty?

Larry@SoCal | 16 juli 2014

A little unseemly but I relate the Tesla to the motor in our refrigerator; that thing has run for 30 years with no maintenance.
Its just the way electric motors are.

jordanrichard | 16 juli 2014

Has there actually been a motor replaced due to a failure vs the whole unit due to an issue the inverter? The only way the motor itself would fail would be if one of the 2 bearings came apart.

EdwardG.NO2CO2 | 16 juli 2014

AC motors are only vulnerable to overheating and ball bearing failure. Tesla manages the heating issue extremely well (better than most industrial service motors) with a liquid cooling system and controlling monitors. I have heard the use the best ceramic bearings available but in any event high quality bearings have great service records as well. It is a simple and powerful electric energy conversion device with only 2 ware points that should last the life of the car!

David Trushin | 16 juli 2014

Most of the drive trains that have been replaced havehad noise issues, not functionality issues. They replace the whole thing because it's a sealed unit. The 15K is the retail cost of repair and not what it costs the company. I wouldn't mind hearing more details of that.

LEvans | 16 juli 2014

The forum member who posted a while back was charged according to him $15K by Tesla to repair his drive unit that was defective. He apparently lived somewhere where he could not get an extended warranty. There are a bunch of threads floating around about drive unit replacements and I hope they have by now figured out what is causing this and fixed the issue.

SCCRENDO | 16 juli 2014

He owns a limo company and you apparently cannot get an extended warranty if you are going to use it as a limo. Had something like 75000 miles

Tâm | 16 juli 2014


This thread is about motor durability.

I have not heard 1 single case of motor gone bad since the day of Roadster to Model S.

Motor is not to be confused with Drive Unit Assembly.

A Drive Unit Assembly houses 3 components:

1) Motor
2) Gearbox
3) Inverter.

Each component failure would give you a different symptom.

If your motor fails, you can floor your accelerator but your car does not move, you only hear the inverter whines.

If your Gearbox fails, you can hear a mechanical breakage, your motor runs but it cannot transfer the torque to the wheels. Your car just coasts with no propulsion.

If your inverter fails, there would be no mechanical noise, your motor does not get enough current from the inverter, it slows down and the accelerator would have no effect.

If there is even a very simple failure anywhere in the Assembly: such as a loose connection, a blown fuse, a defective chip in the inverter, current repair protocol is to drop the whole assembly down and replace it with another one.

This swapping simplifies the repair process for the Service Center and saves you time.

That's why if you complain about the noise coming from the rear, Tesla would be happy to swap the whole thing out for you with no question ask as reported by all affected.

It doesn't matter what is subpar in the Assembly, whether the noise complaint, worn out Gearbox or a loose connection, the Assembly swap is done!

The issue is fixed.

The quoted $15,000 is for a California Limousine Owner Goldie Bhullar.

For some unknown reasons (It's possible that he followed advice from this forum to skip the extended warranty to save money), he did not buy an extended warranty and when it's time to swap the Assembly, he's way over the mileage and could no long buy extended warranty at that time.

For non-commercial owners, you are covered.

Bighorn | 16 juli 2014

Commercial users aren't eligible for the extended warranty.

negarholger | 16 juli 2014

Just to clarify - the warranty is 4 years or 50,000 miles whatever comes first.

So if you drive 100,000 miles year then you are out of the base warranty in 6 months.

johnl972001 | 17 juli 2014

The $15K sounds excessive. Lets say I drive the car for a few years and it's over 50K miles. Then I hear noises coming from the drive assembly. Does that mean I have to shell out $15K to get rid of the noise? Wonder how often does this noise/drive assembluy issue come up?

Compared to an ICE motor, it really never needs replacing. And if it does, it's around $3-$7 for the average car I think.

djm12 | 17 juli 2014

I can't attest to the validity, but I was told by a Tesla mechanic that the motor has been tested up to 4 million miles and was spec'd to 1 million miles of operation. Obviously, if this extended life testing was actually performed, it was likely in a benign environment. Electric motors are extremely high reliability components - an electric motor in any electric car should easily last the life of the automobile, if built to spec and free of manufacturing or production defects.

AmpedRealtor | 17 juli 2014

Let's also please keep in mind that the Internet amplifies problems. When there is an issue, people generally seek out advice from other owners and post about their problems online. By comparison, hardly any people do the same when they are thrilled with a product and have no issues. So let's maintain some perspective. Just because we are reading about issues here does not mean that this is a widespread problem.

With regard to the highway hum, ballon squeal, and other strange noises... those are not directly related to the motor itself. They most likely have to do with the inverter, the mounting points, or may simply be resonance from the components themselves.

Nissan has gone through similar issues with its motor/inverter, requiring them to redesign the shapes of certain parts as well as the motor mounts to reduce resonant vibrations. New drive unit replacements from Tesla include updated motor mounts. It seems Tesla may have redesigned some items for the same reason as Nissan. Here is an excerpt regarding the Nissan issues:

""The motor produces electromagnetic excitation forces when it generates torque. These electromagnetic forces are transmitted through the structures of the connected parts and resonate with the natural frequencies of the parts they pass through to produce noise. To address this issue, the electromagnetic circuit of the motor was optimized to reduce electromagnetic forces, and the shapes of the parts the forces pass through were also optimized, thereby reducing noise and vibration.

"The geometries of the water jacket and the inverter case were optimized to reduce the radiation noise caused by excitation forces input from the motor. Measures were also taken to prevent PCB-mounted components from falling out due to motor vibration. Specifically, a vibration analysis was conducted on the PCB to identify areas where the stress induced by motor vibration was low. The pattern of mounting components on the PCB was then improved such that heavy components like the electrolytic condenser and others are mounted in areas of low stress. This improved mounting pattern suppresses the level of vibration applied to such components."

johnl972001 | 17 juli 2014

I found antoher thread "What's up with Edmunds and drive units" that discusses the current issues with multiple drive unit replacements among many MS owners. Please see that thread.

carlk | 17 juli 2014

Electric motors have very long life because of the simple design. Industrial electric motors last tens of years with much heavier use than the ones in the MS. One example from our daily life is those electric pumps we use for aquariums and fish ponds. Those (chaep) pumps can run continuously for many years without any problems.

jajabor | 17 juli 2014

@johnl972001, may I ask what is the purpose of your research?

johnl972001 | 17 juli 2014

After reading the "What's up with Edmunds and drive units" thread, I am now hesitant on purchasing the MS. I don't want to have to shell out $15K - $30K or more after my warranty expires to replace the drive unit(s).

Unless Tesla comes out with a definite fix, I really don't want to to take that risk.

AmpedRealtor | 17 juli 2014

@ johnl972001,

I think you've made a good decision. Please make sure to come back and let us know when you do decide to buy, that way the rest of us will know when Tesla comes out with a definite fix to what is a non-existent problem for the vast majority of Model S owners.

carlk | 17 juli 2014

By that time Tesla might even have fixed the non-existent seat and interior quality problems too.

LEvans | 17 juli 2014

@carlk: Because when it comes to these things the only opinion that matters is yours and the seat quality is so high that it is the pinnacle of perfection in the automotive world :)

AmpedRealtor | 17 juli 2014

This thread would be better titled "Fishing..."

DonS | 17 juli 2014

$15k sounds like a one-off price for this poor guy who happened to be at the bleeding edge. Tesla will have to come up with a better price and repair system by the time the large numbers of cars are out of warranty. This should cost less than replacing a gasoline engine, not 3 times more.

jbunn | 17 juli 2014

Because ALL Tesla are still under warranty, no owner has been charged a dime let alone 15K. As Amped said, non-existent problem.

Service life on a motor of this type should be about a million miles. Other normal car parts on any auto will be EOL by then.

SCCRENDO | 17 juli 2014

@jbunn. Except for the limo company owner.

Bighorn | 17 juli 2014

This taxi driver went beyond 50K miles without an extended warranty, since it's not available to commercial enterprises. Hence, the reality.

Captain_Zap | 17 juli 2014

A major reason I was not a bit concerned with being an early purchaser is my experience with variable speed motors that had heavy loads and my spouses' experience with electrical systems associated with EV's and battery charging systems.

That, coupled with how happy the Roadster owners with Tesla Service, made me have no concerns at all.

Iowa92x | 17 juli 2014

Electric motors are generally highly reliable, but Tesla has issues with premature drive unit failures. So how can one accurately answer?

Captain_Zap | 17 juli 2014

@ Iowa92x - I rarely hear of failures. I hear about different drives having different noises. Not all drives sound the same.

GreenBehindTheEars | 17 juli 2014

This topic is being discussed in two threads..

Anyway, I am basically ready to pull the trigger and place an order for a Tesla Model S, but these stories of replacements of drive-units are highly unsettling and I'm experiencing a serious case of cold feet..

Living in Europe, I cannot buy the extended warranty, meaning that when the warranty is up after 4 years or 80.000 km (whichever first), I would assume the risk of a break-down of the drive-unit.

I have no doubt that Tesla is working overtime to resolve the issue, but do I dare take the risk.. Even if I don't experience any problems, I would be super nervous when my warranty is over.

I do believe all the stories of the amazing service Tesla provides, but as far as I can see, this has all been during the warranty period. The only incident (I have heard of) with a replacement of a drive-unit outside the warranty didn't exactly show the usual high level of service. - I'm of course referring to the poor sod having to pay 15.000 USD for the replacement.

I'm ready to order - if only Tesla could warm my cold feet..

torst1 | 17 juli 2014

Sadly I think many people are feeling the way you are right now, uncertain if they dare board the ship of Tesla or if they should stand ashore and watch how thing turns out.

As you say the extended warranty is not available in Europe, and that is also the case for several states in the US.

I think the only thing that will "warm your feet" is an official statement from Tesla where they claim ownership of the problem even after warranty ends. Several other brands have done so in the past, the one I remember the best is what Mercedes did after the massive corrosion problems with W210 E class. To get an end to customers uncertainty Merc stated that any corrosion would be on Mercedes dollar. In Norway alone I think there was more then 100 Mercedes's that got a new paint job for free. Faith restored, customers happy.

For those who are reluctant to sign up for Tesla because of the drive train issue an official statement will put an effective end to all speculation, and will end all fear.

AmpedRealtor | 17 juli 2014

If Tesla needs a solution, it's an easy one - offer a 100,000 mile powertrain warranty. When there were concerns about the battery, they included the concerns in their warranty. If there are concerns here, I don't see why they would act any differently.

Tâm | 17 juli 2014


As stated before, there has never a claim of motor failure either from current day of Model S or the old days of Roadster.

Your statement of "Tesla has issues with premature drive unit failures" is misleading because if you follow all the posts and all private and public polls, "premature drive unit failures" is rarely reported.

"Failures" means your car cannot move until you fix it. There was only 1 single such report among the vast many reports.

Most cars don't replace their drive units.

Some who do report them here are not because of "failures."

The cars run fine. Tesla just replaces them to make you happy if you complain about the noise!

Remember, drive unit does have 3 components. When there is noise, that does not mean "motor failure." As noted before, motor failure has its own symptoms.

SCCRENDO | 17 juli 2014

@Tam. +1

GreenBehindTheEars | 17 juli 2014

@torst1 and AmpedRealtor

Yes, that would be an elegant solution.

torst1 | 17 juli 2014


I don't know if you are ignorant or if I am. I can't really believe Tesla replaces the drive unit "just to make customers happy".
If there was no cause for fear we would know. And there would be none customers with their second, third or even fourth drive unit now.

But people do know there was 1 complete failure where the Tesla got stranded.

Mechanical noises tends to be an early warning something will be in need of replacement sooner then later......

johnl972001 | 17 juli 2014


What ever the cause, failure or noise, it's still a $15K issue becasue the whole drive unit will need to be replaced.

The two test M8s performed by Edmunds and R/T (i think), had 4 and 2 drive unit replacements, respectively. That's 4 and 2 replacements too many in my opinion.

Hopefully Tesla will provide a solution soon :)

AmpedRealtor | 17 juli 2014

The vast majority of drive unit replacements that I've read about, including my own, occurred due to a humming noise at freeway speeds. I was very specifically told by the service manager that Tesla was providing replacements due to noise as a courtesy, even though there is nothing physically wrong with the unit. Per the service manager, Tesla feels that the cabin should be quieter at freeway speeds than my drive units provided, and that is why the replacement was offered.

When it comes to the noise issue, a service advisor usually has to verify the noise and/or send a recording back to Fremont so they can make a determination. Again, it has nothing to do with a hardware problem or failure - it is simply superficial.

To be even more clear about any concern that I personally have expressed regarding the cost to fix outside of warranty, it had nothing to do with failure. My individual concern is regarding the noise returning, not the unit actually failing.

We are talking about two different things here.

Tâm | 17 juli 2014


You are the one who titled "motor," not "drive unit."

You are correct "the whole drive unit will need to be replaced" but only if there's a failure, whether because of catastrophe or minor problem such as just a loose connection.

The issue is "need."

Some other posters and myself do hear noise coming from the rear but we do not bring our cars in for replacement.

My car is now more 42,000 miles in 18 months already. I'll wait for another 42,000 miles and I'll bring it in for a preventive replacement, but not now!

"Need to be replaced" is optional right now.

Thus, for me, this "need" is not a problem.

You mentioned 6 drive unit replacements from testing companies who torture their cars to the point of break down.

So, that is not a surprise. It would be a surprise if they give the cars a break and treat them nicely!

Their are racers in this forum too; and they do invite you to join them for a race track from time to time.

But they don't race everyday.

Thus, the responses in this forum is much more realistic than from testing companies.

Tâm | 17 juli 2014

Oops! Thanks Brian H for giving a break this long :)

I meant "There" not "Their" when I mentioned this forum's "racers" :)

Tâm | 17 juli 2014


I plead ignorant because this is not my expertise.

However, you don't to take my words, take @rdalcanto's

But wait! His exact words were not about making the customers happy. His words were opposite: "Tesla was very happy..."

torst1 | 17 juli 2014

Thx @Tam. That link surely puts and end to this thread.

GreenBehindTheEars | 19 juli 2014

I wonder if anyone know if this was discussed on yesterday's Tesla event?

Sudre_ | 19 juli 2014

Hmm... I put almost 20,000 into my Saturn over the 75K mile I owned it. Between oil changes, gas, camshaft sensors, oxygen sensors, spark plugs, belts, radiator flush... I could go on and on.. oh and fuel pump replacement. I got my Tesla right as I was needing a new exhaust system. About 12 years of ownership.
Doesn't anyone else keep track of there expenses on cars?

15,000 sounds cheap but I don't think I'd bother if it was just noise.

I think sometimes people forgets that there is a whole hell of a lot more maintenance than the ENGINE in an ICE that has to go hand in hand with an engine.

Tâm | 19 juli 2014


Tom Sexton did present his findings on his survey of the Drivetrain which includes Battery Pack, Chargers and Motors (I think he meant Drive Unit Assembly that houses the motor.)

He embargoes the finding until after this weekend Tesla conference and he will post it on:

(You know, some people traveled from far away and paid $2,000 to hear the news, so for a free cost for the rest of us, we'll have to wait!)

GreenBehindTheEars | 20 juli 2014

Thanks a lot, Tam. It is only fair that we freeloaders will have to wait a bit :-)