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.
YASA was founded in 2009, a spin out from Oxford University following the PhD of founder and still CTO, Dr Tim Woolmer.
"Over the decades that followed both of these technologies were explored. But despite the potential for weight reduction, smaller size, shorter axle length and increased torque, it was the difficulty in manufacturing the axial flux technology that limited its commercial viability, because the motor could not be made by stacking laminations, as with radial machines."
"The breakthrough innovation came by segmenting the axial flux motor in discrete "pole-pieces", so the motor could be manufactured using Soft Magnetic Composite material.
SMC can be pressed at low cost into a wide variety of 3D shapes. This removed the need for the complex laminations, overcoming the major manufacturing challenge of the axial flux machine."
"In 2025, after a £12m investment, YASA opened the UK's first axial-flux super factory, in Oxfordshire.
The opening of this facility boosts YASA’s manufacturing capacity, setting new benchmarks in e-motor technology and quality, and enabling production to scale beyond 25,000 units per year."
This is awesome. Lighter motors also make electric flight more viable
> 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.
This, or a miniaturized version thereof could change the game for light electric vehicles -
imagine an electric motorcycle that weighs substantially more like an electric bicycle.
Right now it takes about 10-15lbs of motor to produce a 3KW motor for an electric bike, this motor is about 10 times that in power density afaict.
The Livewire electric motorcycles use something like 100-200 lbs of motor to produce 1/4 as much power, 75kw, so that’s an improvement of 8-16x.
Not a game changer but I wonder if ligher motors allow you to do things like have one motor per drive wheel, removing the need for differential gearboxes?
Then you can do clever things with traction control without having to use the ABS system to brake the drive wheels.
Or dramatically change the turning circle on big cars and vans. Maybe even reduce the size and weight of the braking system by taking on some of that role.
Nice observation that the weight isn't that much of a deal compared to batteries for electric vehicles!
It does seem like with this advancement, and the size of these axial flux motors that maybe, all wheel drive vehicles will be the default. As well as sub 3 second acceleration, which can make vehicles safer, for example getting out of the way of an incoming object. Of course it could also make them less safe because that vast of acceleration is kind of dangerous.
But I do wonder if the weight reduction (over 30%) of lithium sulfur batteries paired with these is really going to make a great recipe for all sorts of quiet, long lasting, powerful electric vehicles and robots!
Exactly. Main problem is battery energy density. Cars can drive about 20 kilometers on 1 liter of gasoline. In comparison, Tesla's 4680 cells are at about 272-296 Wh/kg and CATL's Kirin Battery at about 255 Wh/kg. A bit efficient EV often uses 200 Wh/km, so for 1 kg of battery the electric vehicle can only reach 1-2 km. An order of magnitude difference. Theoretically, batteries could go to 1000 Wh/kg some day, which would mean about 5 km per 1 kg of battery assuming all else remains equal.
Somebody's probably already pointed this out, but in the case of motors, making them lighter can make a big difference.
For example, by making the flywheel in a clutch lighter, you reduce the amount of torque it takes to spin the flywheel. Saving 10 pounds there is not a 10/3000lb difference.. it could be a huge percentage of total power output.
I would expect that lighter motor components would potentially allow weight reduction in load bearing components. Not an advantage for SUV-type cars, but for light and ultralight vehicles it could add up to more weight saving and longer ranges.
> 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.
For EVs no but it's huge for flight if it could be scaled down. Paramotors and ultralight planes are on the verge of being competitive with gas they just need a bit more energy density per pound in the system.
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.
I agree with you however I believe weight and safety are in a complex relationship right now, which has nothing to do with performance and handling.
Unfortunately I feel much less safe in a Fiat 500 when a significant portion of cars in the road weigh nearly 3 tonnes and perhaps can't even see me. I suspect most people are in SUVs because they're the pragmatic trade off between safety and convenience, not because they were hoping for excellent performance.
Weight is not the only thing that matters though. You also need to consider center of gravity and wheel base. A YJ Jeep Wrangler and a Honda Fit both weigh around 2700 lbs and they even have similar wheel bases but the driving experience between those 2 is night and day. A Honda Fit can take a turn at speed without feeling like you're going to go flying. You'll feel like you're able to flip making a turn going 20 mph in a YJ.
This is why the first performance mod that most people put on their cars is an adjustable coil over suspension. Dropping the car down by an inch or 2 changes has just as much of an impact as shedding some weight.
Ironically, most people put lift kits on Jeeps but that also usually comes with widening the wheel base and putting on larger wheels/tires.
Driving Volkswagen e-up for the first time was a very unique experience to me. My brain needed to adjust that a car can be that nimble and responsive due to its small size/weight and instant torque from the electric motor.
> I wish more people on the road realized the extent to which weight reduction improves all aspects of the driving experience
This is a blanket statement and completely untrue. Good driving experience is directly correlated to TRACTION, not just weight. And traction isn't just a function of weight - it also is affected by center of gravity, friction between the wheels and the road. Traction is what gives you the perception of being in control of the car.
I used to own two cars of the exact same model - one petrol and one diesel. The petrol is lighter in weight, about 100+ kgs lighter than the diesel variant. And the driving experience on that is slightly scary especially on roads with strong winds. In fact, it is so light that if you drive over tiny puddles or rumbles strips, the car will sway sideways. The diesel always feels more planted because it is front-heavy, thus adding more traction to the front wheels (both are FWDs). I always prefer the diesel for longer drives because of the heft and confidence it provides.
> 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.
Seems to me everyone wants to invest, instead, into something that can be "web scale" with low marginal cost, that is, natural monopolies. There is not enough anti-trust enforcement.
The issue with this type of motor is that it is part of the unsprung weight since it is inside the wheel. This is probably why savings here matter a lot more (or at least in a very different way) than the battery weight.
It compounds. If you have a lighter more efficient motor you need a smaller battery for the same range, that combined weight loss means you meed lighter brakes etc etc, and because the car is now lighter you size of your motor you need is less.....
They claim, this compounding effect works out to basically double the effective weight saving from battery and motor.
ie if you start with saving 50kg on motor, and 50kg on battery, you end up saving 200kg over all. Still only about 10% of a typical electric car.
Yea that's the thing right, the battery is so very much of the weight that optimizing the other parts are "meh" at this point. What is cool is that the 600Wh/kg solid state batteries seems like they are really finally here soon :) i.e removing 200-300kg from a car in one go will be a game changer.
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%.
> 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.
It’s great anywhere you want more power but are limited by space and/or weight for performance reasons. Aerospace, e-bikes, electric race vehicles, electric motorcycles.
But yeah, EVs seem weird except for racing reasons perhaps.
What I can’t figure out is how they dissipate the heat - double digits kw per kg is crazy.
Hub motors are problematic because they increase the sprung weight of the wheel, which loses more traction when hitting bumps. Dangerous while cornering or braking. Scale down a motor like this to 300 HP and you could have an amazing AWD vehicle.
This video https://m.youtube.com/watch?v=WU9Ptibu2WQ&t=179s claims that SMC materials have much higher losses at low frequencies than laminated materials, up to around 400 HZ when they very rapidly pull ahead.
So as the core of a step down transformer for consumer electronics, SMCs would be worse than a laminated core (stack of sheet metal pieces punched with a press, stacked and wound with the windings). But in a motor operating at 100s of rpms, no problem. And as I understand it, in high torque motors the magnetic fields pulse far more often than once per revolution because the windings are many and small, so that several can pull on the armature at any orientation.
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.
> Direct-drive, wheel-hub motors are not well-regarded right now, specifically because they increase unsprung weight
It will always be lighter to not have the motor in the wheel.
> So instead we backport a bunch of the mechanical infrastructure that transfers power from a traditional ICE engine to the four wheels.
No, we do it because it's smart and efficient for freeway-capable vehicles.
Wheels get banged up in use. They're easy to replace for different applications. They're exposed to 200 kph salt spray at hundreds of RPM. They are not a great place for motors.
This may or may not be generally true. The needs around motors in a robot are more about control than raw output (some output is certainly needed). It is possible that this advancement in manufacturing will benefit there, but it is not assured by the information at hand.
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
I'd expect more applications in either aviation or mobile / portable power devices.
As others have noted, battery remains a major factor in overall mass, and motor placement (in-wheel vs. driveshaft) is a concern in ground-transport.
In aviation, battery limits overall range, but a high-power, low-range, lower-mass vehicle could be useful for short-hop flights, manned or unmanned, especially where payload considerations are paramount.
Mobile-power applications (tools, transportable equipment) might also benefit from high power-to-weight, especially if this means that overall weight limits could be more readily met (e.g., total vehicle weight, total carried weight), or additional equipment (or battery) could be provided.
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.
>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. Until some factory in China starts making similar ones, there are not much chances on getting hands on such a motors.
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.
This motor is well more than twice as powerful as the Model 3 motor, so it could eliminate the entire weight of the second motor in the higher performance models. That’s 146kg, the weight of two adults, an 11% reduction.
The Ferrari 296 GTB weighs about 1500kg and the sports version 1300kg. For the cars YASA produces motors for it's much easier to increase the power to weight ratio by reducing weight than increasing power. I imagine an important design point for all of its components is to reduce weight.
Weight reductions on an electric car are self-reinforcing. If you reduce the weight of a component, the battery can become (slightly) smaller, which again reduces weight. At a certain amount of reduction this will allow you to make the whole structure lighter, which will again allow for a smaller battery.
I agree insofar as the motor is not a Big Ticket Item, opposed to ICE cars where the engine block is going to be 10% or more.
Tesla (I know) claimed a 30kg (?) weight loss on their Cybertruck (I know) just from moving their 12V systems to 48V, allowing for lighter cables at lower currents. Not all such potential is untapped, and my hunch is that there is more to be had with structural battery integration, battery cooling, and high voltage wiring.
Depends on your definition if significance, but I think they do. Every kg of useless weight you do carry, lowers your range. But sure, on its own it is not a magic game changer for heavy electric cars.
For light weight vehicles on the other hand, it might be.
If you put several small motors on each wheel you might get some extra weight gains in the form of less transmission needed. Cables weight less than metal structural bars. But yes you are not going to be 500kg lighter.
OK, you can stop being so enthusiastic. We won't afford to buy any vehicles with these motors until the patents expire. I mean, I'm still waiting for epaper screens...
There is no statement about the efficiency of the motor itself. If the energy conversion efficiency is low, then the weight savings will not matter and the car will have even less range.
> 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.
A sufficiently compact electric motor enables mounting it in the nose-wheel of commercial aircraft, allowing it to be driven around like a golf cart. This means the plane can taxi without the use of its engines, just the power from the APU. [1]
Also planes would not have to wait for a tug to pull back from the gate, which improves turnaround times for the airline.
Surely it would be easier to recharge rather than swap batteries? I wonder if in the future war will be like a turn based strategy game as everyone wait for drones to recharge before making a move.
Okay cool downvote me but it's true, most of the weight is batteries and asking a smaller device to do more work will create more heat and wear components faster. It's not a new phenomenon.
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 :)
Amusingly, given the other thread in here with people sniping each other over the metric system, I'm obliged to point out that kg, not g, is the fundamental unit of mass in SI, because even metric can't get away without some silliness.
This discussion is all about vehicles with large batteries, but how about hybrids? With light enough and efficient enough motors, all kinds of designs might become practical:
- Toyota-style hybrid drives could be a lot lighter, and they don’t need large batteries.
- e-bikes with tiny batteries?
- Hybrid aircraft? What if there was a battery large enough for takeoff and landing, a small motor (or pair for redundancy) for cruising and to recharge the battery, and motors and fans or propellers wherever is best from an aerodynamic perspective.
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.
What do you mean? Modern LFP cells have quite high power density. LTO is even higher.
An e-bike with a 100Wh battery and a 300W motor would be extremely useful if it were light enough: you could carry it up stairs, onto trains, etc easily, and it would give plenty of boost to navigate traffic for short distances and make it easier to go up hills. The idea would be that most of the energy would come from the rider. 100Wh of modern LFP cells doesn't weight very much, but you still need to carry around the motor and the structure to support the motor.
In an airplane, you need a lot of power to take off, and weight is a big deal.
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.
> Toyota-style hybrid drives could be a lot lighter
The hybrid electric motor in a Toyota is already pretty comparable in weight to the motor in TFA, but obviously much less powerful. You can see the main hybrid motor of a RAV4 at [0]. If memory serves both the Camry and RAV4 hybrid models are only 2-300 lbs heavier than their gas counterparts.
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) )
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".
The questions I have mostly centre around how much precision of power delivery it has - it is an all or nothing proposition, can it deliver 0.1% smoothly for real world use, and what is the MTBF / duty cycle / failure mode? I would imagine the last thing anyone would want is a locked wheel, or only one wheel delivering that much power. I know this is unlikely, but as someone with a 22-year-old ICE vehicle I do tend to take the long view on these things and want to know how they will fail as much as how they work. Same applies to the Tesla motors - is there much information on failure modes publicly available?
Ok so whats the catch with the technology? Its more powerful, smaller, all readily available materials. Some kind of strange shape, longevity challenge? Difficult to make so costs are tough to bring down?
Just noticed that they are owned by mercedes benz- they will kill it accidentally. Corporate wont be able to roll it out. They will try and capture all the value and kill its potential
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.
>> Each layer of that strip has a different cut in it, so its much more complicated to make.
You can roll a spool of that material and then machine the shape out of it. I've seen this done for axial flux motors. There are other approaches as well, and the cost differences get even smaller if you throw automation at the production process. I used to believe axial flux motors were one of those oddities that won't win in the end, but now that I work with them I'm not so sure. They are at least competitive with radial flux machines.
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.
Readit News
YASA was founded in 2009, a spin out from Oxford University following the PhD of founder and still CTO, Dr Tim Woolmer.
"Over the decades that followed both of these technologies were explored. But despite the potential for weight reduction, smaller size, shorter axle length and increased torque, it was the difficulty in manufacturing the axial flux technology that limited its commercial viability, because the motor could not be made by stacking laminations, as with radial machines."
"The breakthrough innovation came by segmenting the axial flux motor in discrete "pole-pieces", so the motor could be manufactured using Soft Magnetic Composite material.
SMC can be pressed at low cost into a wide variety of 3D shapes. This removed the need for the complex laminations, overcoming the major manufacturing challenge of the axial flux machine."
"In 2025, after a £12m investment, YASA opened the UK's first axial-flux super factory, in Oxfordshire.
The opening of this facility boosts YASA’s manufacturing capacity, setting new benchmarks in e-motor technology and quality, and enabling production to scale beyond 25,000 units per year."
This is awesome. Lighter motors also make electric flight more viable
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.
Right now it takes about 10-15lbs of motor to produce a 3KW motor for an electric bike, this motor is about 10 times that in power density afaict.
The Livewire electric motorcycles use something like 100-200 lbs of motor to produce 1/4 as much power, 75kw, so that’s an improvement of 8-16x.
Then you can do clever things with traction control without having to use the ABS system to brake the drive wheels.
Or dramatically change the turning circle on big cars and vans. Maybe even reduce the size and weight of the braking system by taking on some of that role.
All for the same weight budget.
Lighter motors for mobile robots could also be cool.
It does seem like with this advancement, and the size of these axial flux motors that maybe, all wheel drive vehicles will be the default. As well as sub 3 second acceleration, which can make vehicles safer, for example getting out of the way of an incoming object. Of course it could also make them less safe because that vast of acceleration is kind of dangerous.
But I do wonder if the weight reduction (over 30%) of lithium sulfur batteries paired with these is really going to make a great recipe for all sorts of quiet, long lasting, powerful electric vehicles and robots!
For example, by making the flywheel in a clutch lighter, you reduce the amount of torque it takes to spin the flywheel. Saving 10 pounds there is not a 10/3000lb difference.. it could be a huge percentage of total power output.
[0] https://en.wikipedia.org/wiki/Amdahl%27s_law
Of which there can be two, or even three.
Deleted Comment
It can make cars cheaper, or longer range, or faster, or any number of other designs based on what the manufacturer is looking for.
But to OP's point about flight - stacking 6 Tesla motors is not an option. Stacking 6 of these YASA motors? Much less weight.
Unfortunately I feel much less safe in a Fiat 500 when a significant portion of cars in the road weigh nearly 3 tonnes and perhaps can't even see me. I suspect most people are in SUVs because they're the pragmatic trade off between safety and convenience, not because they were hoping for excellent performance.
This is why the first performance mod that most people put on their cars is an adjustable coil over suspension. Dropping the car down by an inch or 2 changes has just as much of an impact as shedding some weight.
Ironically, most people put lift kits on Jeeps but that also usually comes with widening the wheel base and putting on larger wheels/tires.
It was an absolute shock the first time I braked in the Volvo, not to mention trying to take a corner.
This is a blanket statement and completely untrue. Good driving experience is directly correlated to TRACTION, not just weight. And traction isn't just a function of weight - it also is affected by center of gravity, friction between the wheels and the road. Traction is what gives you the perception of being in control of the car.
I used to own two cars of the exact same model - one petrol and one diesel. The petrol is lighter in weight, about 100+ kgs lighter than the diesel variant. And the driving experience on that is slightly scary especially on roads with strong winds. In fact, it is so light that if you drive over tiny puddles or rumbles strips, the car will sway sideways. The diesel always feels more planted because it is front-heavy, thus adding more traction to the front wheels (both are FWDs). I always prefer the diesel for longer drives because of the heft and confidence it provides.
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.
They claim, this compounding effect works out to basically double the effective weight saving from battery and motor.
ie if you start with saving 50kg on motor, and 50kg on battery, you end up saving 200kg over all. Still only about 10% of a typical electric car.
https://youtu.be/3qjB6GnhloY?si=yqlz7Evuyf5VaghO&t=446
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.
But yeah, EVs seem weird except for racing reasons perhaps.
What I can’t figure out is how they dissipate the heat - double digits kw per kg is crazy.
This video https://m.youtube.com/watch?v=WU9Ptibu2WQ&t=179s claims that SMC materials have much higher losses at low frequencies than laminated materials, up to around 400 HZ when they very rapidly pull ahead.
So as the core of a step down transformer for consumer electronics, SMCs would be worse than a laminated core (stack of sheet metal pieces punched with a press, stacked and wound with the windings). But in a motor operating at 100s of rpms, no problem. And as I understand it, in high torque motors the magnetic fields pulse far more often than once per revolution because the windings are many and small, so that several can pull on the armature at any orientation.
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.
It will always be lighter to not have the motor in the wheel.
> So instead we backport a bunch of the mechanical infrastructure that transfers power from a traditional ICE engine to the four wheels.
No, we do it because it's smart and efficient for freeway-capable vehicles.
Wheels get banged up in use. They're easy to replace for different applications. They're exposed to 200 kph salt spray at hundreds of RPM. They are not a great place for motors.
That is ever more special
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
As others have noted, battery remains a major factor in overall mass, and motor placement (in-wheel vs. driveshaft) is a concern in ground-transport.
In aviation, battery limits overall range, but a high-power, low-range, lower-mass vehicle could be useful for short-hop flights, manned or unmanned, especially where payload considerations are paramount.
Mobile-power applications (tools, transportable equipment) might also benefit from high power-to-weight, especially if this means that overall weight limits could be more readily met (e.g., total vehicle weight, total carried weight), or additional equipment (or battery) could be provided.
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.
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. Until some factory in China starts making similar ones, there are not much chances on getting hands on such a motors.
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.
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.
So yeah, weight reduction on EVs is great.
Tesla (I know) claimed a 30kg (?) weight loss on their Cybertruck (I know) just from moving their 12V systems to 48V, allowing for lighter cables at lower currents. Not all such potential is untapped, and my hunch is that there is more to be had with structural battery integration, battery cooling, and high voltage wiring.
For light weight vehicles on the other hand, it might be.
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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
Also planes would not have to wait for a tug to pull back from the gate, which improves turnaround times for the airline.
[1] https://www.wheeltug.com/
Not very feasible, but an option that has been thought through.
I guess there’s a system that’s gated to track dependent technologies, to track improvements and what they’ll enable.
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!
Same reason you wouldn't use m²/s³ even though that's also technically correct.
Could the motor in question be shrunk down to 1kg, producing 59kW? Probably.
Could it be shrunk down to 1g? No.
The YASA link is primary, links to test data and back story, and has more detail substance and authority.
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- Toyota-style hybrid drives could be a lot lighter, and they don’t need large batteries.
- e-bikes with tiny batteries?
- Hybrid aircraft? What if there was a battery large enough for takeoff and landing, a small motor (or pair for redundancy) for cruising and to recharge the battery, and motors and fans or propellers wherever is best from an aerodynamic perspective.
- Power tools.
An e-bike with a 100Wh battery and a 300W motor would be extremely useful if it were light enough: you could carry it up stairs, onto trains, etc easily, and it would give plenty of boost to navigate traffic for short distances and make it easier to go up hills. The idea would be that most of the energy would come from the rider. 100Wh of modern LFP cells doesn't weight very much, but you still need to carry around the motor and the structure to support the motor.
In an airplane, you need a lot of power to take off, and weight is a big deal.
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 hybrid electric motor in a Toyota is already pretty comparable in weight to the motor in TFA, but obviously much less powerful. You can see the main hybrid motor of a RAV4 at [0]. If memory serves both the Camry and RAV4 hybrid models are only 2-300 lbs heavier than their gas counterparts.
0: https://youtu.be/O61WihMRdjM?t=120
https://yasa.com/news/yasa-and-lamborghini-high-performance-...
Technically a hybrid but probably not what you had in mind?
But how many footballs a small dog weighs?
Which kind of football: the British or the US-American one? :-)
Just noticed that they are owned by mercedes benz- they will kill it accidentally. Corporate wont be able to roll it out. They will try and capture all the value and kill its potential
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.
You can roll a spool of that material and then machine the shape out of it. I've seen this done for axial flux motors. There are other approaches as well, and the cost differences get even smaller if you throw automation at the production process. I used to believe axial flux motors were one of those oddities that won't win in the end, but now that I work with them I'm not so sure. They are at least competitive with radial flux machines.
If it isn't very good, then it might be excellent for drag races, but maybe not so many others.
Also, any power that doesn't turn into torque, is likely to be expressed as heat.