5 ms·

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

poniko 1y ago
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.
- b112 1y ago
  No wonder electrics don't sell well in the US. People weigh more, you're basically saying that leaving grandma at home, is a "game changer".
  - eru 1y ago
    Well, the world's most popular electric car brand (BYD) is also virtually banned in the US. That doesn't help with adoption.
  - mort96 1y ago
    Range being worse with a fully loaded car than with a lightly loaded car isn't exactly news, and not exactly limited to electric cars. I can clearly feel my old diesel struggling more when I'm driving 3 friends and with loads of heavy stuff in the back than when I'm alone. That makes the gas bill more expensive.
    - throw-qqqqq 1y ago
      You probably know already, but ICE cars only convert about 20–30% of fuel energy into motion, while EVs are often +90% efficient. So when an EV has to work harder (extra battery weight or colder weather), you notice the drop in range more. In an ICE, the same load is less visible because most energy gets wasted as heat. This is also why cold weather seems to affect EV range more.
      - jq-r 1y ago
        The unexpected benefit which I've noticed when switching from a small, light car to a heavier, medium EV car is that the latter doesn't drive/feel any worse when fully loaded. Makes the trips that much more pleasant.
      - jabl 1y ago
        > You probably know already, but ICE cars only convert about 20–30% of fuel energy into motion, while EVs are often +90% efficient. So when an EV has to work harder (extra battery weight or colder weather), you notice the drop in range more. There's a kernel of truth here in that Otto engines suffer lower efficiency at part load, however I suspect the real reason is that gas car range is "good enough" and refilling is fast, so one doesn't tend to obsess about remaining range. > This is also why cold weather seems to affect EV range more. That's because a) some batteries suffer degraded performance at low temperature, and b) ICE cars use the plentiful waste heat for cabin heating whereas an EV needs a heat pump or even resistive heating of the cabin air.
        throw-qqqqq 1y ago
        > That's because a) some batteries suffer degraded performance at low temperature, and b) ICE cars use the plentiful waste heat for cabin heating whereas an EV needs a heat pump or even resistive heating of the cabin air. You are making my point here actually. Combustion engines suffer from the exact same, but because they waste so much energy as heat already, less “extra” energy needs to be spent on that.
        mort96 1y ago
        I don't think there's a contradiction here. Electric cars suffer degraded range when it's cold (in part) because they're so much more efficient that they don't produce enough waste heat to heat the cabin. And batteries are so much less energy dense than diesel and gasoline that the extra power draw reduces their range to a meaningful degree.
        Dylan16807 1y ago
        Part of your point is right, part is wrong. Yes heating impacts range in an EV, but it's not really an efficiency thing, it's because you can't get it "free". If an ICE didn't let you harness the heat, you'd see a similar percent drop in range. And for extra weight, it's just not true. Making a motor work 10% harder at 90% efficiency, compared to making an engine work 10% harder at 20% efficiency, both of these are going to reduce your range by 9%.
  - throw-qqqqq 1y ago
    >> removing 200-300kg from a car in one go will be a game changer > No wonder electrics don't sell well in the US. People weigh more, you're basically saying that leaving grandma at home, is a "game changer". Even in the US, your average grandma weighs less than 2-300kg :D
    - liotier 1y ago
      [This post to prevent ulterior posting of "yo mama" jokes]
  - xandrius 1y ago
    That's true only if your very large "grandma" must at all cost sit on your batteries at all times. If we could indeed leave "grandma" home, that would make things better. And they don't sell well in the US because of oil lobbying and think tanks whose sole goal is to make you buy more oil.
  - infogulch 1y ago
    True! If only grandma wouldn't insist on bringing 250kg of weapons and ammunition with her everywhere I'd get much better range in my EV, but alas this is the USA.
    - thelastgallon 1y ago
      250kg grandma = ~20 small dogs 250kg weapons = ~20 small dogs Instead of technological advancements of EV motors, we can immediately use existing pharmaceutical tech (Ozempic, GLP-1) to immediately deliver weight reduction to cars. However, this will be immediately offset by the increase in weight of weapons carried, thanks to Jevons Paradox.
    - somehnguy 1y ago
      Quite frankly I would like to hang out with that grandma. Load it up, I’ll take the range hit.
  - deleted 1y ago
    [deleted]
- klabb3 1y ago
  Manufacturers may just keep the battery size and market the improved range instead? Smaller cars in urban and suburban environments have always had lots of benefits, but since many of them are collective in nature, it has largely fallen on tragedy of the commons, and we got larger cars with larger hoods instead.
  - DennisP 1y ago
    Why not both? For a two-car family, having a good road-tripper and a light sporty car can work out pretty nicely.
  - Qwertious 1y ago
    They might, but so far they don't. Manufacturers are largely switching to LFP (although to be fair they tend to offer a long-range option which ships NMC instead) and the main benefit of LFP is cost. The range of electric cars on the market is largely capped at 500KM/300miles. They could offer more, but they don't.
- davedx 1y ago
  Not true. Tesla themselves said the way they got the Model 3 to be so efficient was by optimising every single part exhaustively. It’s expensive at design stage but results in the most efficiency gains across the fleet - so worth it (especially something like the motors)
nmehner 1y ago
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.
- Kaibeezy 1y ago
  See also the Saab Emily GT project. Even with an older, heavier gen of these axial flux motors they found significant performance gains by controlling each wheel via its own motor. https://electrek.co/2023/04/27/saab-engineers-develop-secret-nevs-emily-gt-electric-car-project/ https://electrek.co/2023/04/27/saab-engineers-develop-secret...
  - nmehner 1y ago
    I didn't want to put the usability of the motor into question or go into a complete evaluation of advantages/disadvantages :) This was just an explanation that weight trimming the motor might be very much worth the effort - even if it somewhat "insignificant" compared with savings that are possible in battery weight.
- close04 1y ago
  YASA doesn't call it a hub motor specifically but that's one place where it helps to save as much weight as possible. And for the cars most likely to have 1000+HP weight matters too. A Tesla motor weighs 100-200lbs, so saving that much weight down to 28lbs on a supercar is highly desirable. I think large drones will be another place where a downsized version of this motor will make a huge difference, assuming the power scales nicely with size.
- rob74 1y ago
  Ok, now I understand why this motor is only used in supercars - installing four (or even only two - according to https://www.mercedes-benz.de/passengercars/technology/concept-amg-gt-xx-amg-ea.html#technology-and-innovation https://www.mercedes-benz.de/passengercars/technology/concep..., even the AMG GT-XX has "only" three of them) hub motors with twice the power of a Tesla Model 3 in any other car would be ridiculous. So, the actual challenge is to make this motor even smaller while keeping the same power to weight ratio, so it can also be used for regular cars? That is, if they want to build something for the mass market, not only for an exclusive clientele?
DrScientist 1y ago
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. https://youtu.be/3qjB6GnhloY?si=yqlz7Evuyf5VaghO&t=446 https://youtu.be/3qjB6GnhloY?si=yqlz7Evuyf5VaghO&t=446
- honkostani 1y ago
  https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
- DrScientist 1y ago
  What's a bit of a shame is they are no longer an independent company ( ie wholly owned owned by Mercedes ) - so that might mean we are less likely to see these motors combined with solid state batteries any time soon.
- hamdingers 1y ago
  > If you have a lighter more efficient motor you need a smaller battery for the same range Nitpick: You can have a lighter motor, but you're never going to have a significantly more efficient motor because existing EV motor systems are already 95% efficient or better. The electric motor is an old and refined technology.
  - DrScientist 1y ago
    I'm not an expert - but the axial flux design while old is been largely ignored due to manufacturing problems that have now been overcome ( so most of the dev has been on the radial flux variety ). And apparently axial flux motors have shorter magnetic flux paths which reduces losses. ie the efficiency gain is due to the switch from radial to axial flux - not some incremental gain on radial flux. Having said that the efficiency gains are relatively small - 1-2%. However again there is a compounding effect, in that the reduction of loss of energy as heat, leads to requiring less cooling - and/or the motor is able to operate a full efficiency over a wider power output range ( as heating the copper increases the electrical resistance ). https://www.stanfordmagnets.com/advantages-and-disadvantages-of-axial-flux-motors.html https://www.stanfordmagnets.com/advantages-and-disadvantages...

poniko 1y ago

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.

b112 1y ago
No wonder electrics don't sell well in the US. People weigh more, you're basically saying that leaving grandma at home, is a "game changer".
- eru 1y ago
  Well, the world's most popular electric car brand (BYD) is also virtually banned in the US. That doesn't help with adoption.
- mort96 1y ago
  Range being worse with a fully loaded car than with a lightly loaded car isn't exactly news, and not exactly limited to electric cars. I can clearly feel my old diesel struggling more when I'm driving 3 friends and with loads of heavy stuff in the back than when I'm alone. That makes the gas bill more expensive.
  - throw-qqqqq 1y ago
    You probably know already, but ICE cars only convert about 20–30% of fuel energy into motion, while EVs are often +90% efficient. So when an EV has to work harder (extra battery weight or colder weather), you notice the drop in range more. In an ICE, the same load is less visible because most energy gets wasted as heat. This is also why cold weather seems to affect EV range more.
    - jq-r 1y ago
      The unexpected benefit which I've noticed when switching from a small, light car to a heavier, medium EV car is that the latter doesn't drive/feel any worse when fully loaded. Makes the trips that much more pleasant.
    - jabl 1y ago
      > You probably know already, but ICE cars only convert about 20–30% of fuel energy into motion, while EVs are often +90% efficient. So when an EV has to work harder (extra battery weight or colder weather), you notice the drop in range more. There's a kernel of truth here in that Otto engines suffer lower efficiency at part load, however I suspect the real reason is that gas car range is "good enough" and refilling is fast, so one doesn't tend to obsess about remaining range. > This is also why cold weather seems to affect EV range more. That's because a) some batteries suffer degraded performance at low temperature, and b) ICE cars use the plentiful waste heat for cabin heating whereas an EV needs a heat pump or even resistive heating of the cabin air.
      - throw-qqqqq 1y ago
        > That's because a) some batteries suffer degraded performance at low temperature, and b) ICE cars use the plentiful waste heat for cabin heating whereas an EV needs a heat pump or even resistive heating of the cabin air. You are making my point here actually. Combustion engines suffer from the exact same, but because they waste so much energy as heat already, less “extra” energy needs to be spent on that.
        mort96 1y ago
        I don't think there's a contradiction here. Electric cars suffer degraded range when it's cold (in part) because they're so much more efficient that they don't produce enough waste heat to heat the cabin. And batteries are so much less energy dense than diesel and gasoline that the extra power draw reduces their range to a meaningful degree.
        Dylan16807 1y ago
        Part of your point is right, part is wrong. Yes heating impacts range in an EV, but it's not really an efficiency thing, it's because you can't get it "free". If an ICE didn't let you harness the heat, you'd see a similar percent drop in range. And for extra weight, it's just not true. Making a motor work 10% harder at 90% efficiency, compared to making an engine work 10% harder at 20% efficiency, both of these are going to reduce your range by 9%.
- throw-qqqqq 1y ago
  >> removing 200-300kg from a car in one go will be a game changer > No wonder electrics don't sell well in the US. People weigh more, you're basically saying that leaving grandma at home, is a "game changer". Even in the US, your average grandma weighs less than 2-300kg :D
  - liotier 1y ago
    [This post to prevent ulterior posting of "yo mama" jokes]
- xandrius 1y ago
  That's true only if your very large "grandma" must at all cost sit on your batteries at all times. If we could indeed leave "grandma" home, that would make things better. And they don't sell well in the US because of oil lobbying and think tanks whose sole goal is to make you buy more oil.
- infogulch 1y ago
  True! If only grandma wouldn't insist on bringing 250kg of weapons and ammunition with her everywhere I'd get much better range in my EV, but alas this is the USA.
  - thelastgallon 1y ago
    250kg grandma = ~20 small dogs 250kg weapons = ~20 small dogs Instead of technological advancements of EV motors, we can immediately use existing pharmaceutical tech (Ozempic, GLP-1) to immediately deliver weight reduction to cars. However, this will be immediately offset by the increase in weight of weapons carried, thanks to Jevons Paradox.
  - somehnguy 1y ago
    Quite frankly I would like to hang out with that grandma. Load it up, I’ll take the range hit.
- deleted 1y ago
  [deleted]
klabb3 1y ago
Manufacturers may just keep the battery size and market the improved range instead? Smaller cars in urban and suburban environments have always had lots of benefits, but since many of them are collective in nature, it has largely fallen on tragedy of the commons, and we got larger cars with larger hoods instead.
- DennisP 1y ago
  Why not both? For a two-car family, having a good road-tripper and a light sporty car can work out pretty nicely.
- Qwertious 1y ago
  They might, but so far they don't. Manufacturers are largely switching to LFP (although to be fair they tend to offer a long-range option which ships NMC instead) and the main benefit of LFP is cost. The range of electric cars on the market is largely capped at 500KM/300miles. They could offer more, but they don't.
davedx 1y ago
Not true. Tesla themselves said the way they got the Model 3 to be so efficient was by optimising every single part exhaustively. It’s expensive at design stage but results in the most efficiency gains across the fleet - so worth it (especially something like the motors)

nmehner 1y ago

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.

Kaibeezy 1y ago
See also the Saab Emily GT project. Even with an older, heavier gen of these axial flux motors they found significant performance gains by controlling each wheel via its own motor. https://electrek.co/2023/04/27/saab-engineers-develop-secret-nevs-emily-gt-electric-car-project/ https://electrek.co/2023/04/27/saab-engineers-develop-secret...
- nmehner 1y ago
  I didn't want to put the usability of the motor into question or go into a complete evaluation of advantages/disadvantages :) This was just an explanation that weight trimming the motor might be very much worth the effort - even if it somewhat "insignificant" compared with savings that are possible in battery weight.
close04 1y ago
YASA doesn't call it a hub motor specifically but that's one place where it helps to save as much weight as possible. And for the cars most likely to have 1000+HP weight matters too. A Tesla motor weighs 100-200lbs, so saving that much weight down to 28lbs on a supercar is highly desirable. I think large drones will be another place where a downsized version of this motor will make a huge difference, assuming the power scales nicely with size.
rob74 1y ago
Ok, now I understand why this motor is only used in supercars - installing four (or even only two - according to https://www.mercedes-benz.de/passengercars/technology/concept-amg-gt-xx-amg-ea.html#technology-and-innovation https://www.mercedes-benz.de/passengercars/technology/concep..., even the AMG GT-XX has "only" three of them) hub motors with twice the power of a Tesla Model 3 in any other car would be ridiculous. So, the actual challenge is to make this motor even smaller while keeping the same power to weight ratio, so it can also be used for regular cars? That is, if they want to build something for the mass market, not only for an exclusive clientele?

DrScientist 1y ago

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. https://youtu.be/3qjB6GnhloY?si=yqlz7Evuyf5VaghO&t=446 https://youtu.be/3qjB6GnhloY?si=yqlz7Evuyf5VaghO&t=446

honkostani 1y ago
https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
DrScientist 1y ago
What's a bit of a shame is they are no longer an independent company ( ie wholly owned owned by Mercedes ) - so that might mean we are less likely to see these motors combined with solid state batteries any time soon.
hamdingers 1y ago
> If you have a lighter more efficient motor you need a smaller battery for the same range Nitpick: You can have a lighter motor, but you're never going to have a significantly more efficient motor because existing EV motor systems are already 95% efficient or better. The electric motor is an old and refined technology.
- DrScientist 1y ago
  I'm not an expert - but the axial flux design while old is been largely ignored due to manufacturing problems that have now been overcome ( so most of the dev has been on the radial flux variety ). And apparently axial flux motors have shorter magnetic flux paths which reduces losses. ie the efficiency gain is due to the switch from radial to axial flux - not some incremental gain on radial flux. Having said that the efficiency gains are relatively small - 1-2%. However again there is a compounding effect, in that the reduction of loss of energy as heat, leads to requiring less cooling - and/or the motor is able to operate a full efficiency over a wider power output range ( as heating the copper increases the electrical resistance ). https://www.stanfordmagnets.com/advantages-and-disadvantages-of-axial-flux-motors.html https://www.stanfordmagnets.com/advantages-and-disadvantages...