First Up Close Look At Tesla Model 3 Drive Unit, Battery, Cooling & More

JUL 26 2018 BY MARK KANE 53

Here are some close-up videos of the Tesla Model 3 powertrain components, the drive unit – motor, single-speed transmission, power electronics and more.

Videos come to us from Ingineerix, who several months ago shared videos of exploration of the trunk and underbody and as you might remember, showed this totaled Tesla Model 3 – this is the car from which the parts come from.

The first video presents the entire rear subframe, which houses the drive unit and suspension. The drive unit with PMSRM (Permanent Magnet Switched Reluctance Motor) and inverter can be seen in the next two videos.

As it turns out, the drive unit itself weighs less than 200lbs (around 90 kg). With a few hundred kW of power, it could be the new popular choice in various EV conversion projects around the world, especially since there will be an abundance of parts as Model 3 will be sold in a volume never before seen in the EV world.

First Look: Tesla Model 3 Drive Unit
This short clip shows the entire rear subframe complete with drive unit and suspension pulled from a salvage Model 3.

Tesla Model 3 Drive Unit Bare
A short exploration of the bare drive unit removed from the subframe and with it’s inverter removed. Before removing the inverter, I weighed the DU and it came in just below 200lbs. Halfshafts use the same spline and interface dimensions as S/X with the exception of the seal shoulder which is 40mm on 3 versus 44 on S/X. However, the seal OD (67mm) is the same, so you could swap in a seal from a S/X to use the heavier S/X halfshafts.

Note that Tesla is using 4 of these exact same PMSRM (Permanent Magnet Switched Reluctance Motors) in the Tesla Semi. Though the gear reduction part is totally different. Same rear casting in fact, even with the vestigial rubber mount that is not being used in the Semi.

Tesla Model 3 Inverter
This is a quick look a the guts of the RWD Model 3 inverter PCB. Impressive design!

Another set of videos are about the battery pack, high voltage system and cooling system. On the top of batteries is penthouse with Power Conversion System (on-board charger and DC/DC converter).

First Look: Tesla Model 3 Battery Pack
This is a short clip of the Model 3 74kWh battery pack pulled from a salvage. It’s not a complete teardown, as I’d like to keep this pack sealed for a future use. More coming soon!

Tesla Model 3 – High Voltage System Overview
Shows how the Model 3 HV system is routed on the bottom of the car. The only part not shown is the connection for the charge port which is located on top. See this video for details on what’s inside the penthouse:

Sorry for the fast camera movements, watch in 1/2 speed (Gear Icon down on the lower right) if you want to get it slowed down.

Tesla Model 3 – Cooling System Overview
Shows how the Model 3 cooling system functions and is constructed. Sorry for the fast camera movements, watch in 1/2 speed (Gear Icon down on the lower right) if you want to get it slowed down.

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53 Comments on "First Up Close Look At Tesla Model 3 Drive Unit, Battery, Cooling & More"

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Interesting info.

Only thing I’d be skeptical of would be the spin-on oil filter for the gear box. I was hoping that unlike model “S” and “X”, they’d use a beefy enough gearbox that wouldn’t tear itself apart. I guess with the gear teeth slowing wearing away, they have the oil filter to pick up the metal chips. My Bolt ev has a beefy enough gearbox that ‘wear’ was never factored in since it doesn’t need to be.

The Bolt drive unit is probably not designed to withstand 1,000,000 miles…

Why should it be? Who keeps a car for a 1m miles? The average driver puts 12k miles a year on their car, so a million miles would equal 83 years of ownership lol.

On the other hand there are already some Teslas out there with 400,000 miles… So not entirely useless. Admittedly, nobody will likely use the Bolt in a similar capacity, so indeed it probably would be overkill. Point is that this is probably the reason why the Bolt doesn’t have this filter.

“Some” – how many? Again, what’s the AVERAGE miles/year of a Tesla owner? If it isn’t 100,000, there’s no reason to engineer a 1m car. What data do you have that says people who drive Bolts don’t use their cars “in a similar capacity” (which means what?) as people who drive a Tesla?

Why don’t facts and data matter to you guys?

A million miles is overkill – yes. But it would be nice if cars could go around lasting 25+ years. It isn’t the original owner anyone is worried about. At some point, if the car can last 25+, that would be nice.

Automation probably will kill so many other cars in 25 years but perhaps Tesla’s can continue to work. Wishful thinking perhaps…

I know of one 400k Tesla. It’s on its third battery and second or third drive unit.

300k+ Volt is on original parts.

Still, ease of part swapping looks simple. I can’t believe that watching all these videos pretty much shows ALL of the mechanical sophistication of Model 3. Man, is that elegant. Not good news for the automotive parts ecosystem.

I feel bad, for the gear head in me. I’ve rebuilt a motor before, and it’s amazing how simpler this is. Yipes. You can see how quickly this tech will take over.

You say that the ‘3’ will last 1,000,000 miles like a Honda Civic or Volvo of Old? We’ll see….

Or transfer 300+ hp to the ground.

“Beefy” has nothing to do with gear wear.

No offense but ‘What an Idiot’. Teslas have trouble with reduction gearing. GM cars do not. sin

The initial Roadster’s 2 speed transmission would ‘burn out’ so to speak, The aluminum rotor bars would overheat so they were quickly changed to copper. But the final single-speed gears seemed ok – or at least I had no trouble with them in 4 years of ownership.

How many ‘famous’ people have had their model “S” drive units changed out at LEAST once? Now, how many Volt owners have? Which company had trouble with ‘murmuring gearboxes’?

That said, the Model 3, what little I know of it, seems to be the most serviceable of all the Teslas to date.

The parasitic overnight battery drain is somewhat of a concern – me wondering why this was not addressed; so I wonder what else was not addressed? Gearbox overloaded? Simple, put an oil filter on it.

Wait, your proof that Tesla has problems with gearboxes is that a 2-speed transmission that Tesla has never put into a production car as the final production spec, from a gearbox vendor that was dropped and never used again proves Tesla has gearbox failures?

Or that a WASHER failure that required a 10 cent washer be replaced somehow proves gear failure?

Or that battery drain proves that Tesla’s have gearbox failure problems?

You’ve destroyed your credibility on this topic by trying to claim that 3 items that have nothing to do with any Tesla Production gearbox somehow proves Tesla has a gearbox problem. You really need to get over your decade-old bvtt hurt over tire wear on a car built a decade ago.

The SuperDope has spoken – (he doubted that it was really me talking on one posting so I always include this moniker when I talk to this imbecile. The 2 speed was sold to a few people. Supposedly they were eventually changed out.

I don’t really care about my ‘credibility’. I’m paid nothing to be here.

Just like on the supercharger disconnect issue (one in which you never admit you were totally wrong – mostly because you just like to hear yourself talk) you deflect the issue. I DID SAY the model 3 was apparently the most serviceable from what I’ve seen, but that I know little about it, as does any other outsider.

Drive units have repeatedly failed on “S”‘s. But THE MAIN POINT is you’ve definitely lived up to your moniker since you are criticizing someone who knows something about this stuff. Meanwhile, you are, at once, both clueless on almost everything, yet TALK CONFIDENTLY like you had half a brain or something.

Bill Howland said:

“The 2 speed was sold to a few people. Supposedly they were eventually changed out.”

Yes, the first deliveries of the 2008 Roadster did have the two-speed transmission, but they were locked into 2nd gear, so there’s no reason anyone outside Tesla would ever have experienced a gear change in a Tesla car.

“Just like on the supercharger disconnect issue (one in which you never admit you were totally wrong…”

That’s because you were the one who was utterly wrong. It’s both sad and amusing that you can’t see how much you embarrassed yourself over that.

“Drive units have repeatedly failed on ‘S’‘s.”

That’s true; that was a common problem for some years on the Model S. And as you say, the problem seems to be the gearbox; hence the often seen (or rather heard) problem of a “milling noise” from the drive unit. But as far as I’ve seen, Bill, you’re the only one who has ever suggested it’s because the gears were not robust enough. I suppose that’s possible, but it’s nothing more than a guess on your part, certainly not backed up by any evidence.

Yeah I’m the only one who talks about it. so what? The disconnect issue is simple enough – from these eyes NIX is BARELY smart enough to comprehend it, but PUSHI you don’t have the brain power to understand it apparently, just like you are too lost to understand that the 2011 VOLT was advertised as 230 MPG – NOT MPGE as you constantly keep saying they are lying about. 2 completely separate numbers in that case. To avoid getting lost in the minutia for other readers – the sequence of events was this: NFPA #70 has required in 1999, and 2017, a “DISCONNECTING MEANS” that is “READILY ACCESSIBLE”. (Each of those terms, besides the obvious, has precisely defined requirements). Firstly, Nix showed pics of temporary, then portable ‘superchargers’. THAT is pretty much his ONLY contribution here, EVER. Those pictures had “Readily Accessible” “Disconnects”. (RADs). By this time, I’ve seen plenty of PERMANENT supercharger installations. Absolutely none that I’ve seen, or that have been photographed by IEV’s, had RADs. Not sure if NIX is an 8 year old cry baby, but here is what he said: “OH so it was required in 1999, and 2017, but, AGH! you can’t prove… Read more »

Bill Howland said:

“…you are criticizing someone who knows something about this stuff.”

No, you know very little about it, aside from some rather narrow parts of the electrical engineering, such as how the motor works. You have managed to convince yourself you know a lot, far more than you actually do; an almost textbook case of the Dunning-Kruger effect in action.

I find it endlessly amusing that it drives you crazy that a guy like me, who has never owned an EV, understands so much more about them and how they work than you do.

Well, that’s because I have both the ability and the interest to practice critical reading and critical thinking. And it’s pretty obvious you don’t, especially given how easily and completely you swallow so many tinfoil-hat conspiracy theories.

Too much ‘Relaxing with your thoughts, Pushi’. Anyone who is paying the slightest bit of attention realizes this is just your canned response when you’re not bright enough to add to the conversation.

You always claim you know so much more than me – but you never prove it. I have formal training in Thermodynamics, and Strength of Materials at the university level. I also have plenty of industry experience.

No offense, but you can’t even get near any of those subjects beyond what WIKI offers. You just claim you know something but can’t show it.

Mostly the stuff I talk about is common sense –

Please explain EXACTLY how I have disgraced my self over the Supercharger ‘Disconnect Issue’….
I’m waiting……. for others here I recapped the whole thing nearby.

Side mounted oil filters have always annoyed me. There is just no way to remove them without spilling oil on the engine or on the ground. Used to have to change the oil in my Toyota with a BIG pan under it to catch everything, and modified funnel so that it wouldn’t run all over the front (4WD) differential.

The solution of course, was I just stopped doing my own maintenance as I got older… 😉

A messy oil filter change at 150,000 miles. Boo Fn Hoo.

Hate to break it to you, but the Bolt gears will leave behind metal shavings just like any other gearbox. GM just doesn’t care so much. The gears aren’t made of adamantium lol.

Am I the only one here who has experience with CLASS I, II, or III loading of gearboxes? You guys are SERIOUSLY showing your ignorance.

And of course anyone who gave you 5 plus points is totally clueless also.

Well, you haven’t actually posted any evidence of whether the Tesla boxes and the Bolt boxes are class I, II, or III. So what is your point?

Are you just trying to remind everyone how much more stressful a high torque motor with heavy shock is to gear boxes, so comparing gear boxes in cars with vastly different torque ratings would be completely silly for any engineer to do in the first place?

The only time it is not silly, Superdope, is if one constantly loves replacing drive units. Or if one has endless amounts of time and money. The best thing about a Tesla is the Warranty.

IF there is higher wear in Tesla gear boxes than Bolt gear boxes, the much lower torque rating of the Bolt motor would explain more than anything else. But since you haven’t provided any statistical long term data to support your suppositions, you are dead in the water. No, your low mileage Bolt is not statistically significant. Meanwhile, Tesla’s, with hundreds of thousands of miles have not had gearbox failures.

Any cherry picked outlier you post of a Tesla gearbox failure is the exception that proves the rule.

Man, what a dope……. Just like door failures, I don’t think there have been many Tesla “S”‘s with no gear box problems.

Tesla techs told me EVERY lock assembly on the “S”‘s have been changed, – so like the drive train issue, or changing out the 12 volt battery 3 times a year in cold weather – these are simply characteristics of the “S”. I’m not disparaging them since this is simply a characteristic of the car. There is probably a Tesla in San Diego that has never had trouble with the doors – but then cold weather there is 45 degrees F.

My Bolt is high mileage. Just like the door issue, drive units have failed on MANY S’s multiple times in some cases. Other commenters here say the same thing since it is so obvious. I, like others, used the VOLT for comparison also.

Bill – why all the anger?
My S turned 60k last month (bit over 3 years). Strangely no door failures, no DU failures. I replaced my 12V battery at 54k. The first one. I say I because I paid for it – they did it. Came to my work parking lot.

I live in NC. My car has been covered in a sheet of ice several times. The door handle failure (if it happens) is now a DIY fix with a $2 part.

Early door handles were a problem. Early DUs were a problem. Early Roadster gearboxes were a problem. But to argue that a modern S has all those issues seems out of place.

No anger here man, – you have to be blunt with these dudes because they are both PUSHY – if you don’t defend your position they’ll jump all over you like a wolf pack.

But your info is wrong. A new Door Actuator is $1200. Installed. I learned that from reading IEVs.

As far as Modern “S”‘s go, I have seen no information that the quality of the door actuator racking gear has been robustified. That is why aftermarket people are making better ones.

I lived in NC for several months during their “HARSH” weather. The news people talk a week before the dusting of snow, and then talk about it for a week after.

The actuator’s racking gear will strip with anything more than a ‘sheet’ of ice.

Being replaced is due to a noise is not the same thing as failing. In many cases it turns out the transaxle wasn’t even the source of the noise. And before you try to attribute it to me, I’m not saying a Model S drive unit has never failed.

Transaxle? Nobody is talking about the transaxle. My understanding, and it could be wrong, but my understanding is that most or nearly all of the drive units which were replaced in early (and not so early) production Model S’s were due to noise from the reduction gear; a “milling noise” as it was called. Now, Nix is correct to point to certain problems such as loose washers, and there was also a claim by Tesla that the problem was a misalignment between motor and the reduction gear set. But it certainly took Tesla an amazingly long time to correct the problem, if that was the only thing wrong. At one time, a survey reported that (if I recall correctly) 36% of Model S owners had had at least one drive unit replacement, and not a few had multiple replacements. That’s not to say that Bill is right about the underlying problem being that the reduction gears were too flimsy — not robust enough — but I think he’s right about there being a very common problem with the reduction gears, and that didn’t go away even when Tesla claimed to have fixed it. As I understand it, the problem has… Read more »

That’s more complicated than an ICE.


There are different complicated systems, but overall the complexity has decreased compared to an ICE vehicle. Especially in manufacturing, as less mechanical parts are necessary.

Someone’s never seen the inside of an automatic transmission.

EGRs, Injectors, Cams, Exhaust sytems, Cats etc etc. That is pretty funny.

You are perhaps unaware that a gasmobile’s engine has 200-300 moving parts? And the transmission quite a few also?

An EV drivetrain is much, much less complicated than an ICE drivetrain, even though it’s electronically more complex.

Defining complexity solely by the number of moving parts is just wrong.

You can really see how this modular design could improve the assembly speed.
Battery, drive system/suspension cradles, body, etc all manufactured in parallel and then just “plugged” together.
Clearly better than building a unit-body structure and bolting on large numbers of small subsystems.

Modern ICE vehicles are the same. That’s how they build the Bolt and Sonic on the same line. Engines, transmissions and suspension systems of ICE vehicles come pre-assembled to the final assembly. That’s also how the Nummi assembly plant was so efficient for Toyota-GM. It’s just modern manufacturing.

Now I’m lusting even more to get one of these in my all composite 63 Vette coupe looking EV in about 1600lbs. Nice they are so simple which also makes them simple to build to.
As an Electronics person the inverter for the power is awesome. So compact, light yet so powerful.
One has to note the absence of large caps, inductors most other inverters depend on. So they have somehow figured out how to do it without them, a big advance.
So will someone please hack the rear drive and supply the needed board to run it without the rest of the ? They have done it for the S/X but that suspension is way too wide for me. I want lighter too as such a light EV.

I’m not aware of an large caps for any OEM EV. If they do have them they are doing it wrong.

The video mentions some capacitor under the board, but I can’t really see how large it is.

(If you want to see large capacitors, there are some in the “power conversion unit” located in the “penthouse” above the battery…)

Man Jerry you’re talking about those Old “Current Mode” inverters? You might try looking at some Pulse-Width-Modulated stuff within the past 30 years. Even the old Square-D ‘Omega Packs’ (the old American Made Steel stuff, not the recent Telemechanique Junk) would run off unfiltered rectified 3-phase and had therefore very very small smoothing caps. The starting point here is the battery, so that is rather smooth dc to begin with. There’s no need these days to use Gate Turn Off devices so the amount of ‘gate’ power required is minimal unlike decades ago. Gate Turn off SCR’s need a considerable pulse of power to the ‘gate’ to shut them down prior to zero-crossing. Or the other way they used to do it is to just SWAMP a plain old SCR so that it would turn off due to ALL the current being bypassed away. None of that complication today exists – that’s one reason why the pricing of modern drives is so unbelievably reasonable. I haven’t heard of any problem especially with the “S” or “X” inverter drives. The Roadster inverter also had no large inductors nor filter capacitors – its ongoing trouble is some of the HexFets overheat, which… Read more »

You get what you pay for: Value.

“The drive unit weighs less than 200 pounds and outputs several hundred kWh, thus making it ideal for DIY conversions.” You gotta wonder about the writers and editors of an ELECTRIC VEHICLE site who can’t even get the units straight for energy and power.

I feel your pain…

This is why the general public don’t want to hear anything about EPA ratings based on kWh numbers. Even EV sites screw up terms like kWh, and the general public is WAY less interested in getting kW and kWh straight!

Heck, they don’t even want to hear the drive unit’s weight in Kilos, much less what the kW or kWh numbers are. Whether it is kg’s, km’s, kW’s, or kWh’s, if it starts with a “k” they don’t want to hear about it. Painful yet true.

DL, he corrected it in the text. The writer here appreciates the difference but just typed the wrong abbreviation. Sometimes you just have to listen to what they MEAN instead of what they SAY. Try not to be too much of a stuffed-shirt about this stuff. Kinda like people getting all worried about 110 volts rather than 120, or a CHARGER EVSE, when they really mean Charging Docking Station. Although it is funny that sometimes, the people OH SO EAGER to correct someone else, through elaboration, show they don’t know what they’re talking about themselves. Like the guy who said 110 is wrong and that juice today is universally 120. Such a person doesn’t understand the concept of “System Excursion”, but I digress…

I know you’re mostly a reasonable guy. Unlike some others that don’t know much and just like to pick fights for silly reasons, because otherwise they’d have nothing to say. To my mind those people are the comic relief here.

To be fair, it is probably a typo. A mistake they should not make but it probably doesn’t mean they don’t understand the difference.

A typo that as of today still stands. At least correct it for posterity!

We looked right away when this was pointed out and could not find the typo. The article says:

“As it turns out, the drive unit itself weighs less than 200lbs (around 90 kg). With a few hundred kW of power, it could be the new popular choice in various EV conversion projects around the world, especially since there will be an abundance of parts as Model 3 will be sold in a volume never before seen in the EV world.”

It has been written that way since it was published. Today, I found out that the error was in a post description, which only shows on Google or in the synopsis on our front page. This is something that is added before publishing and was not the work of the author. Someone obviously didn’t read the post thoroughly when providing the description prior to setting it live. This was not an author error and I apologize for not being able to find where it was to fix it ASAP.

I want to hear Pushi’s accusation fully fleshed out……

Here is his accusation here:

Quoting me regarding Pushi’s buddy Nix: “….“Just like on the supercharger disconnect issue (one in which you never admit you were totally wrong…”

Pushi’s comment: “..That’s because you were the one who was utterly wrong. It’s both sad and amusing that you can’t see how much you embarrassed yourself over that.”

I want it fully explained ” Sad and amusing that you can’t see how much you’ve embarrassed yourself over that”.

Exactly how have I embarrassed myself (in your view)? I’ve recapped fully the discussion above….. EXPLAIN how I have embarrassed myself, since YOU JUST SAID I can’t see it.

The obvious answer is there is nothing to see, since the exposed ignorance and childishness was with your pals, but instead of your typical silly drivel I want you to STAND UP and fully explain something that you just said, to be believed as if you’re the Oracle at Delphi, or some other nonsense…. But here’s your chance to see whether you are a serious person or not.

Or, are you going to be like your buddy Nix and just HIDE?

Ok, he’s hiding until next time. Figures.