Tesla Model 3 Versus Chevrolet Bolt EV: High Voltage Components Compared


Tesla has eliminated or combined many of the HV components found in the Chevy Bolt EV.

We just published a great video by Professor John Kelly at Weber University detailing all the high voltage components of the Bolt EV. One of the first comments to that article was a request by Cosmacelf to do a comparison with Tesla Model 3. Great idea. Here we go.

All these components in the Bolt and assembled into one easy to see grouping. Lots of components stuffed into the small front compartment which normally would house an ICE in a gas car (no frunk in the BoltEV).

BoltEV High Voltage Components

High Voltage Components:

  1. High Power Distribution Module — distributes power that comes from the high voltage battery
  2. Singe power Inverter Module — inverter for the traction motor-converts dc power from the battery pack to 3 phase power for the traction motor
  3. Accessory power module — DC-DC converter-converts high voltage DC power to 12 volt DC power
  4. On board charger — converts household AC power to high voltage DC power to charge the high voltage battery
  5. High voltage battery coolant heater — heats the battery in cold temperatures
  6. Air Conditioning compressor

Location of the same 5 components in the Tesla Model 3: Credit John Kelly, Weber University

What we see is that Tesla has eliminated two of these components. In other cases, Tesla has combined functionality of two Bolt EV components into a single component.

Most interesting is the complete elimination of the battery heater. That function is now provided by the traction motor. Tesla has figured out a way to use the traction motor as a heater even when the vehicle is parked, which saves space and costs associated with the battery heater.

The second most fascinating discovery is that Tesla has integrated the DC-DC converter and the on board charger into one unit that’s located in the high voltage battery “Penthouse,” which is integral with the battery assembly. Access is provided by removing the rear seat of Model 3.

Thirdly, the high voltage distribution module has been eliminated. That function is also integrated into the battery “Penthouse.”

Finally, the traction motor inverter is not a separate unit in the Model 3, S, or X. The inverter is integrated into the traction drive unit.

Fewer parts=lower cost

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108 Comments on "Tesla Model 3 Versus Chevrolet Bolt EV: High Voltage Components Compared"

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More parts integration can also mean more expensive repairs, both in parts and labor. Legacy automakers have been in habit of breaking functions down into smaller replaceable items rather than combining them into larger more expensive combined units for that very reason.

The parts may be more expensive if they’re more complicated, but labor being more expensive? I doubt it. Diagnostics is simpler and repair is simpler. Fewer parts to test. Fewer parts to remove to access what you need to get to. Fewer parts to replace.

but every of these parts have key functionality, so if You have to change inverter You have to changing inverter and traction unit! it’s big cost, but it’s probably module where You can separate inverter. I still prefer Model 3 over Bolt, but integrating modules it’s not advantage in the case of failure, it’s just saving space, connectors, wires etc.

It can also mean that the entire unit can be replaced to fix the car, then brought back to the factory for diagnosis in a more efficient manner than at a remote shop. In aircraft servicing this is the “re-manufacture” principle: it is often more efficient to change out a part, send the original back to the factory, disassemble into components, check each for tolerance, then reassemble into working and checked units than to try and diagnose what is wrong with it, especially when you have to check all the tolerances again in any case.

Yup. Exactly what Tesla did a few years back with all those malfunctioning Model S drive units. Replaced the entire drive unit at the service shop, and shipped it back to Fremont for disassembly, diagnosis, and repair/ refurbishment. That way the customer didn’t have to wait for teardown and repair.

All the smaller replaceable items run into, this loop
1- Find what you think is broken, customer pays, wait for part, replace it.
2- Did it fix the problem? May find out in the shop or customer may find out at home
3- Go back to step 1 if problem not fixed, greatly annoying customer, keep repeating

Or replace whole rebuilt unit ( only 1 part # in inventory), customer pays and leaves

Been through this many a time

Speaking of reliability and maintainability issues, good luck finding parts and a maintenance servicing and repair shop manual for your expensive Model 3 there Hoss.

And good luck finding enough dumb people here who buy into your serial anti-Tesla and anti-EV FUD Rich.

Shop manual is easy to find on multiple Tesla fan sites. (yes I know the difference between an owner’s manual and a shop manual).

Tesla has recently opened up ordering parts.

2012 is calling. They want their meme back.

You can’t work on or buy parts for the Tesla (body parts either) you have to take it to the service center. Insurance on the better Teslas have doubled or tripled because of the $20-$30k quarter panel replacements costs etc. Tesla listened when Henry Ford said he would give away Model T’s if he could supply all the repair parts and labor.

So when you read all those LEAF posts where the whatever electric part broke and it’s going to cost $1,500 to $5,000 to fix, that is cheaper than Tesla? You are kidding if you think just because it is discrete parts it’s going to be cheaper.
Bolt is like LEAF, to service much of the “engine” bay parts you have to remove the whole “engine”. Tesla looks easier, just remove the parts that are affected, not all the parts around it. Maybe I’m wrong.
Traditional manufacturers & dealers will get your money off you one way or another!

To GM’s credit the Bolt is the most advanced production EV among the traditional car makers. To Tesla’s credit the Model 3 is the most advanced production EV on earth.

If today Tesla did not exist and if today GM had a Tesla equivalent fast charge network in place the Bolt would today likely be the top seller by a wide margin on INSIDEEVs Plug-Sales Score Card…. but Tesla does exist.

The traditional car makers need to find a way to step up their EV game ( including more rapid innovation cycles) otherwise Tesla and other emerging Tesla like start-ups will end up owning the majority of the car market share within the next 10-20 years.

uh, no the Bolt would not.
The Bolt is based off an economy car platform, and is an insult to those buying it.
Cheap plastic interior, poor seats, poor “suspension” if you can even call a torsion beam suspension a suspension.

GM went cheap: When you buy cheap you buy twice.

The used car dealers know it’s based off the Sonic platform.
It’s just the general public that’s being fooled.

If you don’t include the price, you are the one fooling people. Average Bolt is $23K post subsidy in CA. $23K Bolt is very good value. Even $25K (post fed only, no CA) is good value.

Wait, you are telling me I can ask for 10k off MSRP right on the lot? Where is this occurring in CA? Where did you find this avg purchase price of 33k?

Google it. Truecar is one, I think electrek page on sale is by maintained ev-vin.


Do you own one? Did you ever drive one?
You just sound like an angry person reporting what he read on the internet. Nothing more.

Enter Tesla fanboy standard mythology 101. The Bolt is a derivitive of another GM compact car. Wrong. Always been wrong. But some fanboys can’t give it up.

The description of “cheap plastic interior” and “hard plastic everywhere” can be found in many, many reviews of the Bolt EV. It’s not a myth; it’s a consensus of reviews. Nor are the uncomfortable front seats a myth.

It’s true that in some ways, the Bolt EV is significantly better than the Sonic. For example, the electronics and displays are much better. But in other ways, like the cheap interior, it certainly shows it shares a common origin with a bottom-of-the-barrel, cheap, entry-level vehicle like the Sonic.

And dude… we recognize comments from the Anti-Tesla Cult when we see them. Y’all keep parroting out of the same playbook.

The seats have improved and yet people keep parroting the uncomfortable seat myth. Also, it is not based on the sonic.

The Bolt’s interior isn’t inlayed with Walnut, but in the Premier that I have it seems nice to me. Some plastic in some places is hard, but it doesn’t feel cheap to me — maybe not quite as nice in some places as my VW Golf, but not like some econobox. The seats are fine for me too, don’t feel any worse than the ones in my VW Golf.

You are correct in saying that the bolt has the interior of an economy car. But that doesn’t mean it’s not a good value. I wanted a commuter car that was fun to drive and not too expensive. My final 2 choices were the bolt and a vw golf gti. I was pretty sure I’d be getting the gti, but when I crunched the numbers the 5 year tco came out the same. When I test drove I preferred the bolt. Simple as that. Gti handles slightly better (low center of gravity in bolt partially makes up for basic suspension) and has a slightly nicer interior and looks better (imho). Bolt is equally quick all the way up to the 1/4 mile. Bolt has true one-pedal driving – this is a huge advantage. Bolt is vastly quieter. Bolt is vastly smoother – another huge advantage. Bolt sticker $39k with a few options. Negotiated to $35k, $28 after tax credit, plus $1200 for level 2 charger at home = <$30k total. Will save me about $1k per year over any comparable ICE vehicle. 5 year tco equivalent to a $24k ICE vehicle. Bolt is better than any car at that price… Read more »

I’m sorry you cannot acknowledge facts as facts, such as the fact that the Bolt has a unique from the ground up platform, and shares not a single part with the Sonic. Take a deep breath. It’s not the end of the world. But the denial ism is quite pathetic. Why it is so important to you is the very definition of ‘fanboy’. Truth isn’t part of your list of priorities which is why dialogue is really fruitless with an ideologue rather than an informed gearhead.

I think one of the biggest reason the Bolt isn’t selling more, is because GM doesn’t want them to sell. They probably can’t really make a profit off of it, with how it is designed and the supply chain of the components, most notably the batteries.

And how is GM doing that while Bolts are sitting on dealer lots? Is there GM mafia going around with guns to people’s heads if they try to buy Bolt? Tell me GM doesn’t want to sell if you can’t buy Bolt (like the unobtainable Tesla 3 base). Otherwise, stop with the FUD.

Well said, Elemental. I don’t think there is much doubt that’s true, and only a GM fanboy is arguing with you.

And yet, you can find Bolts $4K to $8K off MSRP (see link above). Why in the world would there be ANY discount Bolts if GM didn’t want to sell them?

By contrast, there’s zero discount for Teslas, and they are producing zero Tesla 3 SR since Tesla does not want to sell them. If there’s one company not wanting to sell EV by not making them, it’s Tesla.

Yeah, you can get great discounts in ZEV states, where GM actually would like to sell more of them. Not so much in other markets, last I heard…

It’s not selling more, simply because they aren’t building more. They increased stock in the US, and sales are back up.

Which is the same thing really…

You’re basically saying “If things were different, then they wouldn’t be the same.” Yeah, but that’s a tautology… a needless self-evident statement.

If Tesla didn’t exist, would GM be more likely to build a network like Tesla’s Supercharger network? Frack no! GM and other legacy auto makers will never build anything like the Supercharger network; first, because they doesn’t want to promote selling BEVs over their own gasmobiles, and second, because spending the money and resources to build such a network would benefit only… what? 2-3% of GM’s customers, at best? And not much more for any other gasmobile maker, currently.

By contrast, the Supercharger network will benefit nearly all Tesla’s customers. Even for those who never use it, it’s a comfort to know it’s there if they ever do need it.

Even as the EV revolution advances, legacy auto makers are not gonna spend the money to build out anything like the Tesla Supercharger network. (VW’s Electrify America wasn’t built by choice; it was government mandated.) No, legacy auto makers will wait for third parties to build out for-profit EV charging networks, just as third parties built out networks of gas stations for gasmobiles.

Looks like VW is being rewarded for their sins.

The Bolt is the top selling non-Tesla EV in the US.

That’s not saying much though, considering that none of the the few other non-Tesla BEVs even sell outside of a few states AFAIK…

Tesla design is far more elegant than the Bolt or others, not having dozens of pieces joined by cables galore that always reminds of a hobby project. far less bits to fail, with far less seals to leak that are exposed to the environment. Sure larger integrated components are costlier items if you are buying a replace out rite, but rebuilds are the ways to go. No small mechanic is going to rebuild these smaller parts with the huge man-hours and specialized equipment needed. Better to send the whole package to a rebuilder that’s set up and has done it before many times with an inventory of spare bits and the ability to fully test.

Let us remember that Tesla production was a complete mess at one point and in an effort to improve, streamline and reduce costs on the assembly line, Tesla (Musk) introduced many ideas that a tear-down company provided on a typical Model 3 (early build). From that Tesla dropped weight, simplified the manufacturing process and reduced costs significantly. It is a well engineered car, particularly on the battery tech, time-to-charge and range. With continued improvements in the quality of build for the carriage components, Tesla is looking to completely bury the competition. Once Tesla hits a lower price point for their most affordable Model 3, watch out. Consumers will begin sharing stories of range & charging reliability that competitors won’t be able to match for some time. This advantage can place Telsa in a dominant market position for years to come and may spell the death of a few global manufacturers. Ford, Chrysler….are you listening????

The simplifications (which aren’t implemented yet AIUI) pertain to the body, not the power train…

(And we don’t know how much of them actually came from Munro’s suggestions, rather than just internal reviews.)

GM’s design allows for easy replace/repair by anyone. To fix the same components on a Model 3 you would have to remove the battery – that’s not a small task.

Battery removal 1/2 hour give or take. Engineered that way.

I commented on that video yesterday about how horrible the space efficiency of that setup is. They could have easily fit some storage there if they had packaged it better.

Yup. Not enough Tetris players at GM.

When you look at the Bolt “nose” length, even a better packaging like you say wouldn’t have improved the available space for a “frunk” much.

The TM3 has a more traditional “nose” length, in addition to its more compact parts design.

The model 3’s hood is about doube the size of the Bolt’s hood so GM they could have easily added a frunk if it made sense.

I’ve never seen the ‘frunk’ as an advantage. To me it would be a disadvantage. Another body panel to open and see if something fit. And maybe reach over a dusty fender. It’s an artifact of the sedan design. Bolt’s storage is all in one place and therefore more versatile for arranging. However, without the ‘frunk’ the M3 storage would be minimal.

Well, I’ll give you “credit” for finding a new way to bash Tesla. It isn’t often that we see serial Tesla bashers being creative. 🙄

And you’re literally the only person I’ve ever seen claim that an auxiliary storage space is a bad thing.

He has a point. The M3 storage is spread out in two smaller places, which is less versatile than a single larger space.

So how do you make the back of the car have more space?
The skate board design means virtually everything is between the wheels, so the frunk is created because otherwise there is an empty void there.
Other companies haven’t really embraced the skate board design yet because there are still a lot of systems/components under the bonnet or outside that between the wheels location.
Having looked at the Model 3, the boot is decent size, and you also have the space where a spare tire would usually go. Frunk is just more storage, you don’t have to use it, but I bet you are happy it is there of you ever do need to use it.

That would be (mostly) true if cars traded boot space for frunk space… But they don’t. The frunk space is simply a bonus, extra space that doesn’t come at any meaningful trade-off.

The question you should ask – does it make sense to package it tighter? Also using this modular design they could use components on other vehicles. The inverter is already borrowed from the Volt. Tesla has yet to reuse a design with any of the cars they build. I guarantee GM’s next vehicle will reuse some of these components. That’s how you lower cost over time, not just adding robots to a line.

“Tesla has yet to reuse a design with any of the cars they build.”

Wut? The Models S and X share the same complete powertrain, from battery packs to drive units. I’m sure they share many other components, too… like that honkin’ big touchscreen.

Sharing a design is not the same as sharing components. All Tesla share the design, they use the same skate board design. They use the same touch screen type interface.
If you look at other brands, do they use the same petrol tank? I don’t think so as most models can hold a different amount of petrol. Do they use the same engine? I don’t think so, because that is what differentiates their models. So while some components might be shared, there is a while lot that are not.

True, where S and X share many components.

Actually many ICE cars do share the same engine, transmission, body control modules, steering wheels, mirrors, switches, infotainment, etc… That’s how they save cost. Do you actually think they design an engine and transmission for every vehicle model. Those things take years to design. Normally the only difference is software, number of cylinders and the compression ratio and features. If you look at Toyota, GM, VW they only have a few engines and tranmissions that they tune up or down by adding/removing features to meet price points.

If they ever release any other model based on the Bolt architecture (which they promised, but are yet to follow through on), they will reuse *all* these components — so having them separate doesn’t buy anything.

Antrik, in what way has GM ‘not followed through’ in introducing new cars? They promised them in 2020! And they’ll appear based on their track record. GM isn’t like Tesla in that regard. Musk was warned on his attempt to almost completely automate the assembly line, ignored it and found out he was in fact wrong – and admitted it. My position has been the base 35k Model 3, if it is ever built in more than token numbers, won’t appear in 2019 and would see a quick price raise. Musk has already said he’s been dumb on time lines and really isn’t promising a base M3 in 2019 anymore.

Fanboys put Musk in a bad position in that they won’t listen to Musk carefully and more or less commit to things he’s already said maybe can’t get done. Then automatically call anyone a hater that points out what Musk himself has said, or any other pertinent facts that are demonstrably established.

Yes. The Bolt has more copper cabling, and parts are not combined into combo packs. Yet somehow the Bolt weighs 3563 pounds to the M3 SR at 3552 and MR at 3686 ponds respectively. The Bolt has 16.9 cu ft of storage to the M3’s 15 cu ft. The Bolt is still ~$10K cheaper out the door than any M3 you can actually buy. If you travel out of state a lot, the Supercharger network makes M3 the clear winner. Most of us are too busy running in place on our gerbil wheels to do much traveling. But we all like to imagine we could. 🙂

You can’t compare the cu ft of a hatchback to a sedan. They are measured differently. Model 3 has much more trunk+frunk space than a Bolt, although less flexible when folding the rear seats.

I’ve definitely been wondering how they are measured lately. In my research of the 3 to see if we could make it work for our family, I discovered that the cargo capacity is actually bigger than our Leaf, despite what the specs say on paper.

The Bolt has more space. Unless you have short/tiny children, the M3 is not a family vehicle.

Not a family vehicle? By what yardstick?

The Model 3 certainly has as much or more room inside as many or most sedans used as family cars.

This may be only anecdotal evidence, but according to the owner’s report linked below, the TM3 should work just fine if you have 2 kids, but would be problematic on long trips with 3 kids in the back.


The Bolt has a taller trunk and when the seats are down, that is even more room. The Bolt has more space, especially headroom, in comparison to the M3.

No it doesn’t.

It’s $15k cheaper after dealer incentives and it’s fwd vs rwd base Tesla which most northern residents wouldn’t even consider.

I would love a Tesla, but $15k more is a bridge too far for me. I envy those for whom it isn’t.

Without a heavy engine in the front, I don’t think the FWD makes any difference in snowy traction compared to a RWD.

With lots, and I do mean LOTS of experience in varied terrain in snow and ice FWD is superior in snow and ice, by a wide margin. If you are only on flat terrain it might not manifest itself much with a careful driver, but anything more complicated and it will.

My drive is twisty and steep and intimidating to the uninitiated. 4wd and Awd are the best at it with FWD doing almost as well if the driver is experienced. 2wd usually stays at the bottom of the hill if it’s bad. Clearance is sometimes a factor. All of this based on good winter tires (which cuts range).

Based on the above a 2wd M3 isn’t practical for me. That and I don’t want a low sedan seating position (and other reasons too). No, don’t even start on Awd M3. I want efficiency and that includes cost. I was in at @$28k with credits with a Bolt and have 20k miles on. And I live in a rural area.

I beg to differ! Living 10 years at 8k ft (2.5k m) in a Colorado ski area (i.e.. lots of snow), both of my RWD cars were superior on snowy roads to FWD cars. My cars were mid- and rear-engine designs, so like a FWD car, they had most of their weight over the driving wheels. However, the front wheels weren’t responsible for both steering and acceleration which leads to loss of front wheel traction sooner than if the front wheels were for steering only.

All RWD Teslas and the i3 have considerable weight over their driving wheels which makes them perform well on snowy roads.

“Without a heavy engine in the front,” Nobody would build a rear-engine FWD. Strawman argument.

Congratulations on missing the point. Front-engined cars do better with front-wheel drive because of the weight distribution. Cars that don’t have the weight in front don’t benefit from front-wheel drive.

Did you not notice how they stuffed all the EV bits in the front? Wonder why they did that?

1) Makes it easier to work on
2) Can easily be assembled on the same line as ICE cars
3) Looks familar to the buying public

Simple: because the platform it is derived from was designed to have all the stuff at the front…

EVs truly designed from scratch (Tesla, VW MEB, BMW i3) all go for RWD.

I stand by my statement – nobody in New England drives a rwd car around in the winter. Nobody. Maybe one can do that where it’s flat, but not in the northeast.

The weight distribution on a bolt ev isn’t much different than any other fwd car.

Tesla makes amazing cars. I wish I could afford one. And they make awd, so no problem if you live where it snows. Just stop arguing that you can skip the $9k upgrade to awd because Tesla traction control is so amazing blah, blah, blah.

Tesla traction control *is* amazing, as confirmed by many people living in cold climates. But that’s not even my point. My point (or rather, trying to explain the point made by others) is that the reason “traditional” RWD cars are bad in snow simply doesn’t apply to cars that aren’t front-engined. If front-engined FWD cars are fine in snow, so are RWD Teslas.

Under poor conditions like steep snowy, icy drives turning off traction control is often required! Traction control usually uses the brakes to limit slippage at a wheel based on forward speed and what the other wheel does. This creates a situation where it can bog the car down and it loses momentum. The traction control will keep switching to alternate wheels, forward momentum is lost and you’re done. That’s why there’s a button to turn it off. Beyond that, FWD never causes the rear end to kick out under power when going up a hill with sketchy traction. A RWD car will cause the rear end to move to the side, then traction control will make it worse if it hasn’t already bogged down. I’m not talking about icy parking lots on a slope but really tough conditions. And I’ve done this with every kind of vehicle. Every kind! I will say old VW vans were good due to engine BEHIND the rear wheels and the lack of power kept the driver from inadvertently applying too much, a significant issue with EVs – aND no teaction control. Takes a lot of discipline and experience to avoid that as pitches and… Read more »

It’s quite a stretch to imply that the bolt wasn’t designed from the ground up. Maybe there are a few frame members borrowed from another platform, but it’s pretty much entirely new. The battery enclosure itself provides 40% of the platform stiffness – how was that derived from an ICE vehicle?

Have you watched the Weber state teardown of the bolt drivetrain? Is it elegant? No. Is it an absolute piece of cake to repair/replace components? Yes.

Best of all, it’s fwd, which is cheaper than awd and way better than rwd in snow.

Yes, it’s significantly modified, to incorporate the battery — but that doesn’t change the fact that they started with an existing platform, and modified it as needed, rather than starting from a clean sheet. And thus radical changes like going from FWD to RWD were not really an option. Unlike for all the clean-sheet designs I listed.

Antrik, do you EVER do any research? Or are fanboys exempt from that task? The Bolt platform is NOT derived from any other platform. I’ll post a quote from Wiki below. The platform for the Bolt is intended to be used for future EVs in the future. The GM strategy is basically a straight line and I expect two GM production models on the Bolt platform in 2020. One will be a more overt crossover design and I’d guess a sport sedan. There’s nothing ad hoc about GM plans and they won’t be jury rigging on the production line.

From Wiki, and it’s consistent with the press releases at the time.

“The Bolt was designed from 2012 by a team of 180 people in GM’s Korea[12] studio (formerly Daewoo Korea), as B-segment size[32] on its own platform, and does not share elements with the GM Gamma platform cars Chevrolet Sonic/Spark/Opel Corsa.[33][34]”

Seriously, you’re claiming the Bolt EV is “better” than the TM3 because it’s a front wheel drive car?

Clearly you’ve never driven any RWD Tesla car in snowy or icy conditions.

I’m not claiming it’s better. I’m claiming that in northern climes one would have to get an awd Tesla and that car is currently $20k more than a bolt.

I live in New England. Nobody drives rwd cars here in the winter.

That’s funny – you’re not paying attention. Tesla RWD vehicles have served many people very well in Canada and Scandinavia, etc. the Tesla traction control is exceptional, particularly with the near-instantaneous response times you get with an electric drive train.

Of course, it’s silly to claim ANY car is superior to a Tesla in any way when speaking to a fanboy. But FWD is better than RWD in tough snowy conditions on ‘terrain’. Excepting ‘maybe’ rear engined vehicles like an old VW bus. Tesla has nothing demonstrably special when it comes to single axle power or traction control and doesn’t make any claims to that effect. Except it wants to sell Awd versions.

Maybe we could have a snow derby on my drive this winter and video it!

How about comparing apples to apples? AFAIK the Bolt is about 200 kg heavier than comparable combustion cars, while the Model 3 is maybe 100 kg heavier than comparable combustion cars…

I’m not sure inverter integrated into drive unit is a good thing with 3. If a diode breaks in inverter, that will require chomping at the drive unit rather than simple box of chips with Bolt.

A lot depends on operating margins. I use to repair 1541 disk drives for C64. The drive power specs said the power supply needs were .9 amps. Commodore in their bid to save money used a 1 amp bridge rectifiers, those things keep coming in with the rectifiers melted down.

I don’t know if the circuits pulled more power than the specs or manufacturing of the bridges meant some could not handle .9 amps.

But I replaced the rectifiers with 3 amp units and NOT a single one came back. And I did hundreds of these units.

If the parts are over-rated for the power demands then failure will be few indeed, and considering what we know about how the frame of the car is made we already know Tesla believes in over-engineering instead of cutting corners.

True, MTBF does matter. However, tearing open the drive unit to get at a diode in case of failure seems pretty wasteful.

A lot depends on the failure rate, doesn’t it? If the failure rate for the more integrated unit is, let’s say, 1 in 500, then the total cost for producing and maintaining the car will almost certainly be lower, even including the cost of maintenance under warranty. A higher cost to replace one single unit and ship it back to Fremont for disassembly and repair, is going to be much more than offset by 500 cases of lower cost for building the cars. And if the failure rate is, let’s say, only 1 in 1000 or 2000, then Bob’s your uncle! 🙂

Even ignoring the fact that this is a totally hypothetical situation, the inverter in the Model 3 drive unit is just as easily accessible as in a separate housing.

Watch the Engineerex Model3 teardown video. Given a lift, a transmission jack, and basic hand tools almost anyone could pull the rear drive unit in under 1/2 hour. Inverter is bolted on, just remove bolts and pull. The mechanical design of the Model is so incredibly elegant. It’s art really.

The key piece is you have to remove the rear drive unit to get to the inverter.

Conclusion: people who regularly want to tinker with their inverter better not buy a Model 3. All two of them.

Well, considering that almost every new EV announced in the past year or two boasts integrated drive units, I think it’s safe to say there is a consensus forming on that question…

The similarities and the simplicity of both in comparison to any ICE vehicle are more remarkable than the differences between the two EVs. Basically Tesla combined functions as much as possible, and Chevrolet went with a modular approach. I can see benefits and drawbacks to both. Seems like modular would make repair and replacement easier and less costly, while integration tends to simplify things quite a bit, particularly assembly.

The only meaningful savings from separate components are in R&D costs. With increasing volumes, higher integration becomes increasingly attractive.

Great post, George.

One note to all about integrating the inverter/motor. Tesla is not alone with understanding this concept. GM’s engineers are also very familiar with drive-unit component integration. They used exactly that concept with the Gen 2 Volt transaxle. IEVS technical staff (guess who) was right on top of this back in 2014:)


Note that Dr. Kelly pointed out how GM simplified the battery pack cooling concept. GM eliminated the pack glycol loop cooling radiator, out-simplifying Tesla in this regard by relying solely on the Bolt’s AC compressor/chiller to cool the battery pack loop.

Yes, the Bolt assembly shows it is really is just a first generation product with the focus on getting to market fast. Like the Volt, a second generation product would have a much higher level of integration to eliminate cabling and mechanics, and reduce cost. One important observation is GM’s preference to integrate all the drive and electronics components (and even the A/C) into one large assembly, installed as a unit from the bottom, which makes it more compatible with their existing assembly lines. That, of course, is not an issue for Tesla, but makes a lot of sense for GM. Tesla is all about the in-house battery, so it makes sense for them to integrate most of the electronics there, rather than the drive unit. Unlike GM, they also had the luxury of enabling that by designing an all-new assembly process. But Tesla still has HV cabling between the battery and drive, as does GM. That’s a 2 wire DC cable in both cases since the inverter is collocated with the drive unit motor. I don’t think you can conclude one approach is better than the other (not withstanding the first gen Bolt’s lack of integration), it is more… Read more »

I don’t agree with the first generation product. GM already had Volt 1/2, Spark to know what they needed to do. I think this is more about component sharing. These modular components could easily find homes in other GM EV’s. Tesla remakes everything for each vehicle it makes.

Tesla didn’t remake everything g for the S and X. They share at least the packs, drive units/inverter, and 17” touchscreen.

AIUI, it shouldn’t be too hard to transplant the “penthouse” components to a new battery — so I think Tesla could actually ship “bare” replacement batteries if they see a cost benefit…

Well, thanks for the shout out and comparison! I wonder if the DC-DC converter share actual electronic parts with the charger, or whether it is more of sharing high power buses and eliminating cables? Either way, nice tight integration.

I’m guessing that if the on-board charger burns-out (e.g. lightning strike nearby causes a blown diode on the charger), then the penthouse would be opened and the charger replaced? In that case, it would be more accurate to say that several components have moved from the front hood area to the under-seat penthouse container (not integrated). But if you must replace the entire penthouse to fix a blown diode on the charger, then yes, it’s been integrated… but is that a good thing? Who’d want to pay for a $4k charger module just because a simple contactor or the much smaller 12v DC-DC converter died?

It looks like the 12v DC-DC converter and the charging rectifier (separate modules on Bolt) are integrated to one surprisingly large “Power Conversion Unit”. Judging from video(*), it looks like that unit can be replaced (yay!) if you remove the rear seat, then remove the “Hat” from the “Penthouse”. As an owner, I’d definitely want to know that repairs to failure items can be made economically once the vehicle leaves warranty.

So… yes, those two modules have been integrated together into one PCU in Model 3. And you could say that the battery and everything in the penthouse has been “integrated” for assembly purposes, just as the drive modules have been integrated for assembly. But you wouldn’t really want true integration to just three replaceable assemblies, unless Tesla starts offering drive module or battery+penthouse swaps for a reasonable price (similarly, imagine if GM wanted to swap the Voltec2 drive assembly because the seals wore-out in the A/C compressor).

(*)see 43 minutes 47 into Jack Rickard’s video “Tesla Model 3 Battery Removal and Disassembly”.

“What we see is that Tesla has eliminated two of these components. In other cases, Tesla has combined functionality of two Bolt EV components into a single component.”

Sandy Munro said much the same after his Model 3 teardown analysis was complete: Said that Tesla was remarkably advanced in getting one part or one assembly to perform the function of two or even more, thus reducing the number of parts and making the car less expensive to build.

However, it would seem to come at the expense of making the car harder to design, and less flexible in changing the design. I’m not saying that eliminates the advantage, just pointing out that there is a trade-off involved.

And probably more difficult/expensive to repair or replace.

John Kelly is a hero in the EV world. He teaches his students every detail about the advantages of EVs and consequences of ICEs without shoving it down their throats. Although he has been an EV owner himself, he is now forced to drive an ICE since it’s the only affordable vehicle that can be customized to accommodate a wheelchair. I’d love to see Tesla find a way for him to get into an X.

I wish it had a damn battery heater. I drive around with limited regen to and from work because of this.

In a M3??? What temperatures are you talking about? Charging in ETD mode doesn’t warm it enough? Preconditioning doesn’t??? Doesn’t the M3 have a dedicated heater for starting the battery cold? Or is it stuck using heat from the drive motor?

When you combine parts, repair costs are much more.