Tesla: hairpin winding electric motor

I’m no engineer. What I know about electric motors ends at electricity running through coils creates magnetic fields, the reason why you should not coil the wires to tidy up your computer setup.

Talk of hairpin winding electric motors at Investor Day piqued my interest so I got Google to clue me in.


Requirements for electrical machines in traction applications keep increasing in terms of power density and efficiency. The use of hairpin windings is a relatively new development and sees increasing attention due to its beneficial electromagnetic and thermal performance. Hairpin windings are solid conductors as opposed to stranded wire used traditionally and hence can achieve a high fill factor and good thermal performance. This makes the use of hairpin windings attractive in designs where high power density and efficiency are required.

Fill factor can be up to ~0.75, compared with 0.4-0.6 for conventional round wires
Better thermal performance
Enable a highly automated manufacturing process
Less flexibility for winding configurations
AC losses
Higher cost

I question the higher cost disadvantage, automation should offset other costs.

Tesla’s mission is to cut costs and to improve the environment. They talked about using software to model the best configuration instead of running tests. Sandy Munro talked about seeing them welding which gives a clue to which design they are using. Permanent magnets with zero rare earth minerals. The result is a drive train made up of a $1,000 motor combined with a $5,000 battery pack which makes the $25 to $30K mass market vehicle not just feasible but high Gross Margin to boot. Tesla pundits suggest that the new motor will find its way into the current model lineup in addition to powering the new mass market EV.

A more efficient electric motor cuts fuel (electricity) costs, no rare earth means less mining, a mass market priced EV means faster transition to renewables. Win, win, win…

The market price action suggests that the ‘investor’ audience is more interested instant gratification than in long term ecology.

The Captain


I suspect it’s just going to take people a while to digest the information.

I initially heard that Investor Day was “disappointing” and that the next gen car wasn’t announced and was a big disappointed myself just to hear that.

Then I watched two videos: The Rob Maurer condensed version of the Tesla presentation… which blew me away. And the analyst panel discussion at the bar, which included Munro’s entertaining pontification (including the hairpin winding motor… and I’m glad you posted here about it). Half hour for the Maurer video should leave anyone’s mouth hanging open:

As Munro later mentioned (multiple times)… nobody will be able to stop Tesla. Their plan and their ongoing implementation just has them pulling away more and more.

Except maybe the Chinese. Because, in the final analysis, they can operate at a loss as long as the government chooses to support it… and regardless of what the financial reports say.

He is no fool who gives what he cannot keep to gain what he cannot lose.


My best guess is that Musk and his people think it is very risky to attempt to complete two new vehicles at the same time. So they are now making the decision to either:

  1. Go full speed ahead and get cybertruck into full, and smooth, production. Then, later, begin the process for the model 2 (or whatever it will be called). Less risky.
  2. Get cybertruck into production AND get the “model 2” (or whatever it will be called) into design/factory/production at the same time. More risky.

They may decide that they don’t have enough engineering staff to do two at the same time properly. Or they may decide that they are mature enough to be able to do multiple designs simultaneously. We shall see.

The thin, round wire of the conventional winding technology is substituted by copper bars,

I think the big difference here is wires that do not have a circular cross-section. Thus no air gaps between windings. Oddly related, back in the early 80’s I had some woofers from Radio Shack whose voice coil was wound with square wires as well. And for the same reason.

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I disagree. Build the Cyber Truck in Austin starting in 2023 and build the Model 2 (or whatever it will be called) in Monterrey, Mexico starting in 2025-6. These two models are sufficiently apart in development stage for this suggestion to make sense.

The Captain


It could be much sooner than that. The Mexico ground breaking will be this month and it wouldn’t surprise me if details of the next generation platform occur during that ceremony as it appears that will be what this giga factory will produce.

Giga Shanghai took a remarkable 11 months to construct while Giga Germany and Giga Texas took about 20 months. The state governor of Nuevo Leon said that Tesla was going to accelerate construction and have the site online by the end of 2023. That seems impossible, but you never know with Tesla.


Giga factories probably have multiple assembly lines when fully developed. Once opened with one line they continue installing additional capacity. Hence more than one date may be involved.


Yes, exactly. Not at the same time. Sounds like you agree! The cybertruck will be in production smoothly by end of '23, then they will turn to the model 2 and it will be in production smoothly in '25-'26.

From the Bloomberg article (going by memory):

The mayor said “This will be the largest factory in the world”.

That would be impressive… Boeing’s main factory in the Seattle area is pretty big. Some have noted that the Giga Mexico rendering LOOKS like a double giga factory.

I still think it’ll be the next gen small car, at least to start. And despite company direction that it is intended to supply Latin America (implied “only”), I see most of the volume coming to the US… because the entire Latin American market for all vehicles is much smaller than the US market… and it isn’t likely Tesla will capture the entire Latin American vehicle market. :slight_smile:

Probably intended to meet small(er) car demand for the entire Western Hemisphere eventually.

He is no fool who gives what he cannot keep to gain what he cannot lose.

Your best guess is completely wrong. Tesla is currently ramping two new vehicles: expanding Giga Nevada to mass produce the Tesla Semi; and going full speed on ramping Cybertruck production at Giga Texas.

The currently stated intention is to go full speed on getting the next gen vehicle into production at the new Gigafactory. Their estimate is that they start rolling off the line in 18-22 months, so mid to late 2024. The constraint is not risk or engineering, it’s (as always) getting enough batteries in production. Ramping up 4680 production themselves and from suppliers (like Panasonic, who won’t have 4680s in quantity until a year from now) is key to being able to produce the next gen vehicle(s).



Word to the wise watch Mercedes, the company will be entering this race. I just see the headlines now with Google building the company’s software and the margins per unit. This is Germany’s best hope of leading in the EV market. JMO

Don’t forget that mass production in the semi tractor market is a relative thing. The entire US market is something like 100k - 200k units a year. Selling 5000 in the first year would be quite an accomplishment.

Tesla probably doesn’t need to get the same speed efficiencies out of their semi production as they need on other lines.

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If, as stated, each vehicle is worked on by its own small team, there should be little conflict. In my previous post I just wanted to highlight the timing happenstance that the factory where the Cyber truck is going to be built is up and running while the factory for the new model is yet to be built.

The Captain

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I don’t think the semi really counts (re: “production hell”). They’ll probably sell a few thousand of them at best this year and next year. I’m talking about vehicles that will number in the 100,000+ volume range.

I haven’t watched the whole event yet. When was this “stated”? Who exactly stated it? Do you have a link to it? If it was stated by Tesla, then why were so many people disappointed about the lack of info about the next gen vehicle?

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Generally speaking, because people are idiots. Well, also Wall St. doesn’t want to hear anything beyond “Here’s what we’re shipping this quarter.”, so being idiots kind of comes with the territory.

Here’s a video from Autoline explaining to the ignorant what they just saw.

Short and sweet.

The basic automotive assembly line hasn’t changed much since 1913. But Tesla has a revolutionary idea of how to put cars together. And this new process will be the key way it can come out with a $25,000 car and still make a tidy profit.



The price chart favored by traders is the six month chart. For traders “18-22 months” might as well be Eternity! :imp:

The Captain

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Great explanation! It ties in with a discussion at Seeking Alpha about Tesla’s 4D factory design (I don’t remember the exact term they were using). It stressed that instead of an assembly line there were independent production cells. Any cell, at any time could try out something new and if it worked it would be incorporated into all the other same process cells. This is what allowed Tesla continuous innovation without pausing the whole plant.

By contrast, a sugar mill is governed by the seasons. Dry season December to April, wet season May to November. Trucks get stuck in the mud during the wet season, therefore they make sugar from December to April and do plant maintenance from May to November. They could double the efficiency if they could make sugar all year round.

At Tesla they don’t let tradition overrule first principles. It’s Amazing!

The Captain