Mercedes‑Benz starts large‑scale production of electric axial flux motor

Here’s a build series of an ex-Apple/NASCAR/Tesla engineer turned YouTuber swapping Tesla Model 3 drivetrain to a 50s Jag.

https://youtube.com/playlist?list=PLoTU9_iCGa6i_C38pwQyg0pBG...

As an antique BMW enthusiast, I know some people that have swapped electric motors in to 2002s and 2000 CSLs and they said it was actually a pretty disappointing experience. You lose the vintage driving experience entirely.

Number 1 problem is battery weight though. Not electric motors.

I have a 84 w123 300D, and would love to add some more power to it. Lightweight hub motors would be great, but any decent size battery would be at least 200lbs+, which is hard to do on a old chasy.

  > BYD can be lighter because they skip on safety gear and proper structural elements - in my experience.

From the animation: "Torque grows with the cube of diameter"

That seems like a pretty cool cheat-code to get more power. Perhaps it will mean you will start having cars with more distance from the ground to accommodate the large dia motor wheels.

This is happening now in the openinverter.org community

I'm going to replace the differential and the automatic transmission in my truck with a 4-cylinder engine and an electric transmission.

Yup, the visualization didn't help me understand the concept any more than plain text. Superficial in the way that you would expect from a system that has no real world reference for what it is creating.

To get something better I expect more than a one-shot is needed, and the knowledge to guide it in the right way.

Look at the beauty of an interactive visualisation of an internal combustion engine made by a human being - https://ciechanow.ski/internal-combustion-engine/

It’s possible to actually learn something from this, whereas the one fable created is just slop with pretty colours.

Code is here https://github.com/mohsen1/axial-flux-motor-explainer

Feel free to steal! This was one shot with Claude Code. You can take it and adopt it to your need

Yeah so the relationship between speed, power, frequency, size (both in the direction of primary flux excitation and in the direction orthogonal to both that and the movement), and torque at nominal values of current density (for a given conductor losses are proportional to the square or this value and to the total mass of that conductor in the machine; that's independent of any of the other scaling parameters; note this is absolute power not percentage) and peak flux limitations (core saturation, permanent magnet demagnetization), are sadly not trivial if you express them in a way that is even just _valid_ for the modern days where we can support electrical frequencies up to around a megahertz at scales up to around 100 kW, and even harder when you remember that core material has severe frequency dependence of it's limits.

E.g. for example for a given electrical frequency and decent radial flux synchronous machine, power density is quite static and torque density can actually be dialed quite freely from 2-pole machine (turboset in gas turbine running on the grid at 3600 rpm (or 3000 rpm outside NA and some Pacific Islands) to 40(+) (example deployed at Hoover dam, 180 rpm). At those higher pole counts, the center of the rotor is no longer electromagnetically active, because the magnetic field lines keep to a narrow ring only about as thick as each pole is wide. Unfortunately it's mechanically not that trivial to handle a cylindrical shell with a small air gap (this needs to be significantly smaller (about at least 10x) than the pole width) when using substantial torque and speed.

Circumferential velocity is practically limited by hoop strength of whatever the outer region of the rotor is made of, even if it's all very nicely balanced, because eventually the magnetic armature flux source (wires or magnets) will fly out.

Higher electrical frequencies limit the field winding core's magnetic permeability (magnetic field/force strength amplification relative to vacuum, for same electrical current) which hurts efficiency by dropping the useful mechanical power component of field voltage while the voltage resulting from the current (that needs to happen to cause the magnetic field in the direction of movement that causes the mechanical force) due to wiring resistance stays. (I think the permeability gives the ratio between voltage and current for otherwise identical mechanical load conditions and winding shape?)

Thinner wires have less fill factor because the insulation has to stay the same thickness as per-winding voltage stays, but magnetically inactive terminations are less wasteful (for losses and mass) when a decent number of effective turns (>>1, think >10~50 for most of the benefits) are used.

Note while the armature necessarily has an even number of poles in it's construction (north/south), the field is not forced to that.

Indeed, the iirc most smooth torque (under practical mechanical feasibility limitations and without undue sacrifice of efficiency) results from having a prime number (of field windings, in WYE-style connection) exactly one off from the armature pole count. Note that for low losses all these torque-smoothing techniques _require_ only a single electrically directly driven winding in each slot (per mechanical field pole) and with that only GCD(field_slots, (armature_poles / 2)) windings get to share an electrical half-bridge (one single wire going to a single voltage-output terminal on the electronics board; note mainstream BLDCs have 3 of these, classic fridge compressors have 2, and modern stepper motors (e.g. 3D printer) have 4).

Any time you have multiple windings driven by different electrical source voltages you're wasting heat in the winding because the lowest-loss would require all conductor in the slot to to perfectly evenly share current.

There's just one problem with that: you need a nearby slot with exactly opposite phase to even possibly use more than a single (half) turn of "winding" in the slot.

If the voltage is still enough to not loose too much in the connections, you can use transistors developed for efficiently powering modern computer chips from comfortable voltages like 12V, but even then a "winding" has to be much longer than an armature pole to mitigate the losses of spreading the return current sideways to where a slot carries the current in the reverse direction. Once the voltage at the transistor is over around 10V the benefits of more precise control of the field magnetization to the armature position (and how the shapes distort the field lines from anything that would look like a sine wave) could be useful. In theory that'd also provide direct access to electronically control the air gap (well, net force normal to the air gap "surface") which _could_ be an alternative to mechanical bearings for very thin-shell constructions. See maglev trains for a pretty practical application of using an electric motor to also levitate the "rotor" in a place where a mechanical bearing ("train wheels + bogies") performs poorly.

Yeah, I'm at once awed that something like that can be auto-generated (I presume?) and disappointed that it doesn't usefully or practically improve my understanding, beyond written synopses and human videos, at all.

Stuff like this reminds me that we still need a human in the loop to edit, to improve, to advance.

Auto-from-scratch just doesn't really achieve anything of actual value.

Hundreds of examples of axial flux motors exist online. If you look at the visualization it shows the iron cores in a perpendicular orientation with the hub. This is correct, but loses so much of what makes these specific motors interesting. The angled nature of the grey cores and copper wrapping smoothes the transition between each magnetic field.

Basically it is a pretty version of a dumbed down partially incorrect answer. With a knowledgeable user it would be very good, but he has no idea he is wrong. I’m not sure what Dunning Kreguer with graphics should be called.

You don't. You didn't know before either. The difference is trust. How do you trust it as much as you do the hypothetical humans making such representations? That's up to you.

The question is for you to answer, first. Gotta do that work. (My answer will differ from yours.)

Then, predictably, finding the collection of supporting details + vetting the content in question.

This is an issue we, technology-folk, ought to help guide our non-tech-co-folk through engaging with, BTW. Our responsibility is rising with tech becoming more deeply entrenched / required for society's operations.

And is development of batteries (and better magnetics) not just chemical engineering and material science?

Motors might be a 'solved problem' - there might not be much innovation, Maxwell's laws aren't changing any time soon, but there will surely be a lot of incremental improvement - an early 1900s ICE is considerably worse than a 2000s ICE.

> The Chinese EV industry is actually lead by development of batteries

This is the core point, but it applies for the whole of the industry. Motors just don't matter. An electric motor is an almost vanishing component of the weight and complexity of an electric vehicle. Cut the mass of the thing *in half* and you're looking at 100kg savings, tops. You could do that with a Model Y by just changing the roof material to something boring and not glass. You could almost do it by shrinking the oversized-as-is-the-fashion wheels.

So... it's great that Mercedez-Benz is producing these, I guess. But it won't make their cars anything more than incrementally better. Which is why we're seeing them crow about it in a press release and not a spec sheet.

I thought that for a long time the german supply chain had an advantage in terms of the precision engineering to create drive chains for ICE - but EV's don't have the same number of moving parts and hence... end of advantage?

According to wikipedia[1] the first industrial steam engine (1712) was invented almost 100 years before the invention of the steam locomotive (1804), arguably its greatest evolutionary feat.

[1] https://en.wikipedia.org/wiki/History_of_the_steam_engine

> The US' lack of breakthroughs in EVs has little to do with technology or expertise and everything to do with an administration that is openly hostile towards EVs and renewable energy in general.

It has nothing to do with the current administration either. For one thing, China's dominance predates it. For another, the EU and Japan have failed equally hard at capturing any meaningful EV marketshare.

The current admin is actively hostile to EVs, but I think the real problem was the chicken and egg issue of charging stations: they wouldn't be built because there wasn't enough demand for them and EVs would be limited in sales because they wouldn't have chargers to use on the road.

This is where Tesla made a huge difference with Supercharger stations. I am no fan of Elon, but that work was fundamental in making EVs viable in America.

1. There is still no good answer for air transport, trans-oceanic shipping, long-haul trucking, and long-distance rail. ICE will be used there for a good while longer.

In Formula E the drivers control engine behavior and regen. It is much better than F1 right now.

It would be awesome if they would implement a crude rule: no computers. You can use a computer to design the car--CAD/CAM/CAE are all fine--but no stored program computers are allowed in the race car. I think that would improve F1 tremendously.

I am somewhat confused at the intensity of pushback for the statement “leading electric vehicles.”

Chinese EVs are leading and that doesn’t necessarily mean being the best, most advanced vehicles. They are leading in value/pricing, and in many regions they are leading in sales.

BYD sells almost double the EV volume of Tesla globally as of December 2025. They are objectively leading in that respect.

I think the parent comment of yours made a good point (or at least adjacent to a good point) about China’s ability to enter the market: they can’t compete with 100 years of internal combustion engine development along with the vast parts supplier network of the West, but they can compete on battery chemistry, battery supply, motors, and the more vertically integrated EV space where automakers don’t need to depend on a huge network of parts suppliers like they did in the past.

I also think that a lot of pushback to the innovation that China is delivering is criticism that is stuck in the past. If you buy a Xiaomi car, it integrates perfectly with all your Xiaomi consumer devices. You can control your rice cooker or robot vacuum from your car’s integrated infotainment system. This type of approach was exactly what Apple was going to deliver before they abandoned their automotive project.

Or, you can buy a Mercedes and you’ll get a car with more precise handling and perfectly tuned driving characteristics. The infotainment system looks like Windows Vista.

Which side of the aisle do you think most consumers care about? I think most people buy into Xiaomi’s approach.

Listening to the heads of the American and European car companies say the same and driving in them in china. I know that is different than personally disassembling one and reviewing it, but I am not sure the incentive for the other companies to say they have inferior products, unless it was a play for subsidies or deregulation of some form.

Personally I feel that the rest of the world continues to dramatically under estimate China’s progress and technological advancement at our own peril. Is there fluff and are their lots of untrue claims, of course, but that is certainly not something they have a monopoly on.

Aren't you getting your analogy backwards? American supermarkets have the same role in the story as Chinese cars.

It was Yeltsin.

i wonder how much heat you'd have to dump if you just used a resistive load and heatsinks. aluminum isn't very heavy. Look at the size of a rotor and brake shoe on modern cars, it can't be that much larger surface area as a heat sink to dump the charge. Although someone would have to test it. Since EV are so smart, wouldn't they know that all routes generally are downhill, and thus stop the charge at 80% or something? Further, the absorption phase means you have to dump excess current somewhere anyway if you're over 80% charged.

Interesting, it seems like keeping the battery at some level below 100% (e.g. 80%) would make sense then because I don't think regen would ever top it off that much right?

My understanding is that after 80% the rate of charge a lithium ion battery can accept diminishes.

Could the 80% Li-on battery accept the charge from the brake regen fast enough? Or would it still have to be drained somewhere else if the battery could not accept it?

Or you could dump the power into a realllly loud horn

> that very thing the reader is wondering about

Don’t mistake your curiosity for everyone else’s

It's a press release.

Yes. If you have a laser printer, that windup sound you hear at the start of a job is the polygon mirror motor spinning up thousands of RPMs - those are PCB stator motors. As were VCR head motors.

"Advantages : A motor can be built upon any flat structure, such as a PCB, by adding coils and a bearing." https://en.wikipedia.org/wiki/Axial_flux_motor with image of "A miniature DC brushless axial motor used in a Digital Data Storage drive, showing the integration with PCB construction techniques."

Floppy disk drive motors, but for cars.

No, it means the motor is smaller and it can be put into the wheel

It's poorly worded. There aren't three motors per axle, there are three motors total: one on the front axle and two on the rear axle.

The translation's a little woolly.

For the AMG GT4 there will be 3 motors: two at the rear, and one at the front.

My interpretation (and my German's pretty lousy) is that each motor is combined with a gear system in a single package, and they're calling the overall package (motor plus gears) a High Performance Electric Drive Unit (HP.EDU).

The two rear motors will probably be independent, so no need for a mechanical rear diff (it'll be electronically controlled).

There's no mention of a front diff, so it's unknown whether that's built into the front HP.EDU or is a separate mechanical diff).

To build on what others have said. Multiple motors per axle allow you to get rid of the diff, and you get torque vectoring basically for free.

Then there's braking. More driven wheels means more braking energy that can be recouped via regen. In traditionally rwd cars you lose out here because braking energy tends to be directed forward.

Also there's packaging. One large motor might impinge on the cabin.

Also you get benefits wrt mass production.

A smaller motor is easier to handle. Potentially could avoid the need for high voltage cables. Which eases repair.

I got the impression that there were three motors altogether and they were integrated with the axles.

I would be careful about that video, it seems relatively "explaining this new amazing innovation that has no/negligible downsides (please invest in us)" rather than "explaining the practical pros & cons of this technology".

The AI voice is annoying, the content is as personal a a vanilla yogurt but the animation is clear.

I'd like a 600 HP 1.5l supercharged V16 - doesn't even need to be in a car, mainly just to listen to!

https://en.wikipedia.org/wiki/British_Racing_Motors_V16

V5?

https://en.wikipedia.org/wiki/VR5_engine

We owned an vw inline 5 Passat (quantum in North America). Good engine and synchro awd.

Since they're relatively compact they will probably start stacking them. Like pancakes.

Stick two of them together on the same axle then.

> Axial flux motors aren't some new sci-fi invention

Indeed not. The first ever electric motor was an axial flux motor built by Michael Faraday in 1821. It's definitely not a new idea.

The energy density on super capacitors is pretty bad. If you imagine full power 200kW braking for 5 seconds that's 1 mega joule and at a best case 8 watt hours per liter you're going to need 35 liters minimum. Really you probably need to double that so you can float up and down and never fully saturate the capacitor as power inflow is going to drop as you get closer and closer to fully charged.

https://en.wikipedia.org/wiki/Supercapacitor

So how do you stop then if the batteries are (close to) fully charged? You'd need to shunt that power into a big resistive load, and then dump that heat.

Can regen brakes keep a car stopped? I would think that the braking force diminishes as the rotor speed approaches zero so it wouldn’t keep you in place on a steep hill, but I’m not sure.

well you could have really cheap drum brakes that probably would last the lifetime of the vehicle. Maybe not even hydraulic - electro-mechanical with a mechanical (E brake) fallback.

even better a motor brake already is a thing. Its kinda of like air brakes, requires current to disengage and looks liek a little clutch thats slapped on the shaft or housing.

I don't think my logic would lead to only one country with a launch rocket. Russia and China do not really have the option of using American rockets.

Britain however does have this option and as far as I know it has never had a problem launching satellites, so I guess it's worked out so far.

Yeah. Traditional car makers have enormous demand for EV innovations. Germany has more and bigger traditional car makers.

The UK is by far the best country to raise venture capital in Europe, and is the third largest market in the world after the US and China...

That is also not guaranteed. VW (with its array of brands) leads the european BEV market by a lot. [1] (sorry I only found data for April 2026 right now but earlier months were similar)

One additional point of data. In Q1 of this year they delivered 200K BEV worldwide [2] while Tesla did 350k [3].

Calling that 10 years behind is not warranted in my opinion. I would agree to say competitive and challenged.

[1] https://cleantechnica.com/2026/06/01/europe-ev-sales-report-... [2] https://www.volkswagen-group.com/de/pressemitteilungen/volks... [3] https://ir.tesla.com/press-release/tesla-first-quarter-2026-...

Mercedes always brings their latest technologies to the highest tier of cars first. Almost every major innovation has first debuted on the S class

    > "instead of applying engine breaking when the driver takes their foot off the pedal, they went to great lengths to _move the break pedal_ in proportion to the amount of engine breaking that is currently being applied as per the VCUs command"

Regenerative braking slows the car more aggressively than an ICE where you take your foot of the gas, so the pedal change isn't putting on the brakes, it's communicating to a driver used to ICE that the car is slowing more than might be expected.

There may also be a sports-related reason for people who habitually left-foot brake.

    > "Why not move the gas pedal too?"

The equilibrium of "good enough vs technological simplicity" for cars was probably reached in the 1950s. Everything after that was more or less solving "non-issues" with ever-increasing complexity ;)