> Could lead to significant efficiency gains for EV's, because 1/4 of the motor weight means better power-to-weight ratio... a lot of things will automatically get better.

EV motors are already lightweight. The electric motor in a vehicle like a Tesla Model 3 already weighs less than you do. Reducing that one component by 75% would be a weight savings equivalent to about a half of a passenger.

Not a significant efficiency improvement for vehicles that weigh over 3000lbs (or double that for many EVs).

Every little bit helps, but this isn’t a game changer.

I wish more people on the road realized the extent to which weight reduction improves all aspects of the driving experience... it really does compound unlike any other change that you can make to a vehicle. IMO heavy vehicles are a scam and the antithesis of the direction we should be moving.

> In 2025, after a £12m investment, YASA opened the UK's first axial-flux super factory, in Oxfordshire.

It’s a little sad to me that fundamental innovations in electromechanical engineering like this get just a few million in investment, yet if this had been yet another derivative software startup with “AI” in the pitch, they’d probably have 10x+ or more investments being thrown at them.

But EVs are already heavy because of the battery. I suppose percentage-wise the motors don't make much of a difference (?)

Tesla Model Y's battery is 771 kg. The motor in Model Y weights about 45 kg, about three times as much as the motor in the article. By reducing dual motor configuration weight from 90 kg to 28 kg, we reduce total powertrain weight by 7%.

This is a negligible improvement to most things about an EV. Motors are already extremely power-dense.

There is a single exception, and it's a big one. Direct-drive, wheel-hub motors are not well-regarded right now, specifically because they increase unsprung weight (the part of the car more closely coupled to the road surface than the passenger) and this impacts handling substantially. So instead we backport a bunch of the mechanical infrastructure that transfers power from a traditional ICE engine to the four wheels. We're paying that bill already, on almost all production EVs. Quadruple the power density and simple, 1-moving-part wheel hub motors look like a lot better case versus central driveshafts and mechanical linkages.

Batteries are the bottleneck.

Even if motors were literally weightless and mass-less, EVs would weigh more than ICE cars.

It's like making a more efficient CPU for your phone when all the power is eaten up by the cell-modem, screen and RAM. People wonder where the practical battery life gains are and theyre miniscule in practice

> According to YASA, this is achieved without using exotic or expensive materials, so the design could actually be scalable once the demand kicks in.

That is ever more special

>In 2025, after a £12m investment, YASA opened the UK's first axial-flux super factory, in Oxfordshire.

In Bay Area that is small investment in a startup which would be able to lease a small office

>Could lead to significant efficiency gains for EV's, because 1/4 of the motor weight means better power-to-weight ratio...

that would help VTOL a lot. Unfortunately YASA motors are priced for supercars and availability seems to be low.

I'm more excited about light electric vehicles. (Bikes, tuk-tuks, what-have-you).

Only the absolute weight of a motor counts, because consumers of passenger vehicles do not require 1000 hp.

How far does YASA's tech allow the motor weight to scale down, for applications where you don't need the power?

Can you make it 2.8 pounds instead of 28, if all you need is 100 hp? Likely not.

> because 1/4 of the motor weight means better power-to-weight ratio...

1/4 of something that is a small fraction of the total weight of a car means very little improvement in overall power to weight ratio.

I suspect that gaining 40% of car seat weight would be much more beneficial even if way less sexy.

Better for robotics as well.

I don't see the weight reduction being very significant.

If we take a Tesla model 3, I believe it weighs 1611kg, and the motor shows up at 80kg if you google it (no idea if this is correct). This YASA motor by comparison weighs 14kg. So, this would drop the vehicle weight by 66kg out of 1611, so that's a 4% saving.

> Could lead to significant efficiency gains for EV's

Not really. EV's are very heavy from non-motor weight. A Model Y weighs ~4300 lbs. A motor that is 75 lbs lighter is a 1.7% savings. That's not nothing, but I wouldn't say "significant". You can do better by swapping for fancy wheels or eliminating some of the glass roof.

And really this is true up and down the electric vehicle world. Weight-sensitive applications are always going to be completely dominated by battery weight. Making the motor smaller just isn't going to move the needle.

Basically this is good tech without an application, which is why it's having to tell itself with links like this.

saving 30 kg of weight on a 2000 - 2500 kg car won't lead to "significant efficiency gains"

> This is awesome. Lighter motors also make electric flight more viable

The next innovation we need is Aerial refueling[1] for electric planes. High density swappable batteries and high altitude wind/solar plants that can swap batteries mid air. Perhaps some billionaire will develop a large fleet of these to service all flights! If no western billionaires, we just have to wait for China to develop this tech.

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

The other aspect is that a smaller motor with the same power generally has higher efficiency, by necessity, since it has less heat dissipation. So higher power and higher efficiency and lower size/weight all go together. It’s a great synergy.

It will probably lead to cars that fail sooner and are cheaper to build

> 59kW/kg

At this point why don't we get rid of the k prefix and write 59W/g?

Edit:

I was half joking, but various answers mention kW being standard for motors, kg being the SI unit for mass etc. All true, but as used here in a combined unit, which means "power density" it still would make sense IMO. It's not like the "59" tells you that it's a strong motor and hence you want kW to compare it to other motors. You can't, it's just a ratio (power to weigth). W/g just reads much nicer in my head. Or we could come up with a name, like for other units. Let's call it "fainpul" (short fp) for example :)

59 fp is a new record for electric motors!

Much better you should post it and somebody mark the banner ridden one for deletion.

A much better link .. and probably not to late to change it via [edit] on submission in your view..

The YASA link is primary, links to test data and back story, and has more detail substance and authority.

My first thought too.

While I see Toyota-style hybrids as designed for efficiency, there's also the performance hybrids like the new Porsche 911 T-hybrid where an electric motor spins up the turbocharger to eliminate lag while another integrated into the gearbox adds power. There is no "EV mode" so it doesn't need a large battery.

Arguably the most important characteristic of a sports car is light weight, so lighter motors would be immediately useful there.

The size of this motor is moderately interesting, but the power density doesn't really matter for most of the things you just mentioned. Almost every one of them is limited by the amount of batteries you can put in for both weight and power output reasons.

There's indeed a huge number of applications where lower weight electric motors could be useful.

Not sure about that, but if you ask me, a really small dog only weighs up to 7 pounds - or otherwise said, this motor weight as much as four fat Chihuahuas ( https://en.wikipedia.org/wiki/Chihuahua_(dog_breed) )

New performance ratio: horsepower:dogweight.

> But how many footballs a small dog weighs?

Which kind of football: the British or the US-American one? :-)

Lol. I was confused by it also. I have no idea how much is 28 pounds, and I could imagine how a small dog can be anything from 1 kg to 10 kg. It happens that the motor weight is ~13kg, but I'm still not sure that 13kg dog counts as "small".

123.5 cubic centi-litres

Not sure about footballs but 28 pounds is about the weight of a child, a bag of rice, or a dumbbell. Hope that helps!

American football or international futbol? If American, it's twelfteen furlongs.

Axial flux motors are difficult and expensive to make.

Motors need to be made of laminated steel sheets to reduce parasitic eddy currents. The laminations need to be thin in the direction of the direction of the flux. For radial flux motors you just punch out a shape and stack a bunch of sheets up. For axial flux you have to wind a strip: https://15658757.s21i.faiusr.com/2/ABUIABACGAAgmviFqAYozvPw-...

Each layer of that strip has a different cut in it, so its much more complicated to make. The shape and manufacturing method typically impacts efficiency; YASA avoids that by spending more money. Efficiency is an unavoidable requirement of high power density- heat is the limiting factor, and going from 98% to 96% efficient means double the heat.

The mechanical demands on the motor are also much higher- radial flux is balanced since the magnetic force pulls the rotor from opposite sides. Axial flux motors are usually one-sided, so the magnets are trying to pull the rotor and stator together with incredible force. That also makes vibrations worse. Extremely strong, expensive bearings are required to handle it. With permanent magnet rotors you need a jig to lower the rotor into place; they can't be assembled by hand. That also makes maintenance more difficult and expensive.

First, no, it won't scale like that.

Second, don't forget that you're trading one complexity for another. Eliminate a drive shaft and you still have to get power to the wheel somehow, which means now you're running high power electrical cable in a very dynamic environment with exposure to the elements. On top of that, you need to cool the electric motor, so you're probably running some kind of fluid out to it. Not that it isn't a solvable problem, but it probably doesn't reduce the weight much, if at all, when the system is all added up. You'll find that while you eliminate an axle, you still need to mechanically connect the two wheels together (look at the rear subframe on an FWD car) for strength, which also reduces the weight loss. Then the steering on the front... etc.

Until a more significant change than this motor (where maybe a 2.8lb motor could produce 100hp without needing active cooling), we're better off with "inboard" motors still.

Is it really easy to forget?

It would almost have to be very efficient -- they're saying it can do something like 500HP continuous, and it doesn't have enormous fins all over it for cooling.

Exactly my thought as well. You can have all the horsepower you want but if it doesn't convert the electricity efficiently, it's not going to be useful for normal consumer cars.

Peak power is a number that can be manipulated. You just dump short circuit current into a winding. Even if that peak lasts for 1 microsecond, you can "claim" eye-watering horsepower numbers.

I wonder if we defined peak as sustained peak over 100 milliseconds, or some more meaningful number, what that would do to the claims. You aren't really generating meaningful torque over 1 microsecond.

I sort of wonder how well these things can be scaled down.

Wheel hub motors are obviously bad, for harshness reasons, but if you could have a motor like this weighing 1-2 kg, and put one on each wheel, that'd be okay.

Power-wise this would be okay if things are linear. 26 kW per wheel sustained power output is more than enough for a light car. The question is what torque a scaled-down machine can be expected to have.

> That's 28 pounds

or about the same as a small dog

Thanks. Do you also happen to know the power density of the motors in the average EV car? Because the article uses "nr of Tesla Model 3" as a unit, which is meaningless without further details about it power density.

That’s an excellent video!

It's not a lab model (according to the article), but it's likely aimed at performance cars. For consumer cars, 150 KW / 200 HP is enough and efficiency is more important than weight.

Of course, when consumer car efficiency increases, they won't necessarily get higher ranges because the manufacturers will instead try to downsize the battery.

You sent me down a rabbit hole.

I have no idea, but:

I searched axial flow motor in wikipedia, and the last link is:

https://newatlas.com/technology/conifer-iron-magnet-electric...

So maybe?

Rare-earth magnets do not fall under “exotic”.

I had the same question - would this make, I dunno, super efficient wind turbines?

> "There has been significant progress in the construction of molecular motors powered by light and by chemical reactions, but this is the first time that electrically-driven molecular motors have been demonstrated, despite a few theoretical proposals," says Sykes. "We have been able to show that you can provide electricity to a single molecule and get it to do something that is not just random."

"something that is not just random" ==> Probably a long way away from something in production. I wouldn't hold off on any urgent transportation needs waiting on this tech.

Pretty much any modern car battery out there. Many of those allow 350 kW charging, discharging that quickly is even easier.

Current motors seem to suffice just fine:

https://youtu.be/ysE8FMhAPH0

the first thing I thought was building a robot dog with these, they probably already built an evangelion with these they aren't showing us

Their website claims "4 X more torque and double the power densities of current technologies".

A bit handwavy, but given the inherent torque advantage of electric, I doubt torque is an issue. If anything, a lot of EVs would probably do better with a touch less torque.

Source: https://yasa.com/technology/

It is important if you want to put the motor in the wheelhub. Too much unsprung mass kills vehicle dynamics.

Drone motors are aircooled though, so I think you actually want the radial configuration.

Saving up even few % of weight while not compromising on comfort/safety is a holy grail for any decent car manufacturer.

Not sure why the negatives in this thread (maybe too many folks hold TSLA stock?), this is properly awesome (r)evolution.

Oil cooling. Besides this is a peak power value, so thermal constraints don't matter. Continous power is given around 350-400 kW.

(Sources: https://yasa.com/news/yasa-smashes-own-unofficial-power-dens... and https://yasa.com/technology/)

Surely there is still some merit in having competition in the market place?

Tesla is getting out of the car business

Mercedes should buy Tesla you mean.

We're a country who even sold our water to the highest international bidder ...

What would make you think we wouldn't sell our tech crown jewels also? (throwing in our grandparents and children to sweeten the deal).

I wonder if Americans don't have a mental image for measurement units so that they alway use some physical object as a reference. Sure, its useful to use a common object as a reference but I don't see that much often in other places.

Most people usually understand what it means something to be 20 meters, 5kg or 2 liters intuitively. Like, when I hear that something is 60m tall I intuitively think if it as 20 story apartment building and don't benefit from the extra info about how this is like 18 elephants stacked on each other.

If I were a self-respecting journalist, I would've used 3.26 gallon milk jugs. Small dog automatically goes to which breed? Chihuahua (fits in a toddlers purse) or Border Collie or Golden Retriever or Saint Bernard (needs an SUV/minivan)? 4 different classifications based on size!

Imperial dog or metric dogge?

Americans are very weird when it comes to metric. They often quote mobile phones as having something like "a six inch screen size but now only 12mm thick" - pick a measurement system people !

Is even a 13 kg dog "small"? It certainly does not feel small if you are carrying it upstairs.

The link you're quoting, the one posted, is a second hand US report.

The primary company link is from a UK subsidiary of Mercedes-Benz and is (almost) fully metric (the fundemental units US weights are officially defined with respect to (for more than a century now)).

See: https://yasa.com/news/yasa-smashes-own-unofficial-power-dens...

  Earlier in the summer YASA achieved 550kW (738bhp) from a 13.1kg version of its new axial flux prototype motor, equating to an unofficial power density world record of 42kW/kg

  Now latest testing of an even lighter 12.7kg version on a more powerful dynamometer has shattered this record, with a staggering 750kW (>1000bhp) short-term peak rating, resulting in a new unofficial power density record of 59kW/kg

Bag of potatoes?

Sometimes leads to humorous effect https://x.com/SheriffAlert/status/1221881862244749315

> Large boulder the size of a small boulder is completely blocking east-bound lane Highway 145 mm78 at Silverpick Rd

Car companies, both electric and non-electric, frequently advertise rated horsepower of their vehicles, even non-performance vehicles. In the US, horsepower is one of the key metrics for a vehicle overall.

Every car listing, review and so on mentions either the bhp or kW, along with the 0-100km/h or 0-60mph which is functionally the same as listing the horsepower to weight ratio.