now if only this was packaged as part of a conversion kit for ICEs. 3.5k$ would be a magic price. And a shop could similarly charge to retro it at that price. So hopefully 7k$ total. Mind you the work shops will bank even more with all the "scrap metal (engine block, catalytic converters etc)" so maybe we'd see free swap deals.
Your main hurdle is the driveline surviving the initial torque shock, so even with that 20sec power drop you still have the initial torque from a full battery as a risk.
Not at all unsolvable, you just want to consider it before you break your axles!
This is already a solved problem, as the accelerator peddle in an electric vehicle isn't a simple on / off switch, it's connected to a computer that talks to an electronic speed controller, thereby providing drive-train safe power application.
The same sorts of governing functions are computer managed in an ICE powered vehicle too.
Of course, this is in response to an engine swap, just talking out that these are all decisions to be made and thought about. People regularly drop in bigger ICE motors and blow their drivelines up. There is absolutely the option of plonking in a big torquey electric motor and sending all you've got through it, without upgrading axles or using the right settings/setup in your motor controller.
This isn't a theoretical problem, even some ICEs with a lot of torque have warnings against flooring them from standstill to avoid axle/drivetrain damage.
Oh I didn't mean solveable in the theoretical sense, I meant it is very much a practically solveable problem. Buy bigger axles, use a nuanced motor controller etc. It's a problem you have to solve for ICE swaps/tunes too. Just discussing that it's something you will likely want to consider if you're swapping from something low torque.
The scrap metal isn't really worth all that much. Maybe the cat is worth something.
I do agree though that it'd be great to be able to buy new high-performance conversion motors for a reasonable price. (I'm working on an RX-8 conversion with a Netgain Hyper9. It's a decent motor, but 120 horsepower isn't a lot compared to the ~230 hp engine it originally had, or the motors that come in mid-range modern EVs.)
On the other hand, a smaller, more powerful motor would probably need a lot of cooling. The Hyper9 is air cooled, and is supposedly about 96% efficient when it's in its optimal range. Sometimes it's nice to have things be simple. (The motor controller generally does need water cooling. It's not technically mandatory, but highly recommended.)
I wish that were literally true, it would have been a lot easier. Those engines are heavy (especially with the exhaust manifold/alternator/flywheel/etc.. hanging off it).
None. I bought the car with a bad engine in the first place, so it's not like I threw away a perfectly good engine. (I even took the old engine to a guy that rebuilds rotaries; he took it apart and said there weren't any parts that were worth trying to reuse.)
This is true of a lot of conversions: they aren't "destroying" a perfectly good ICE engine, they're salvaging a car that would otherwise be sent to the wrecker because it doesn't work anymore.
I think the RX-8 is a great platform for conversion because it's a nice, reasonably modern car and they can be had for almost nothing if the engine needs rebuilding, or is too damaged to be rebuilt.
That may be true of some rotary enthusiasts still; I don't really know that many. I could see it being more of a thing with RX-7s, which are kind of rare and expensive. RX-8s aren't super common, but they're also not hard to find. And if the engines are due for a rebuild, they're sort of like old pianos -- people will practically give them away.
Also, climate change is a thing. I'd expect more people are aware of that these days, and its hard to justify running such an inefficient engine even if they are admittedly really cool.
Do you have the swap project posted anywhere? Would love to follow. I'm more in favor of a K-swap if anything but I've seen videos of an FD3S with some electric motor and it seemed pretty rad; I lack the details for it, though.
I don't. I've been meaning to, just haven't gotten around to it. There's a guy in the UK doing a pretty similar conversion documented on Youtube. He's using a Leaf motor and batteries I think.
Even with an e-conversion you will often have to address the ECU in some manner. Even if you have a full standalone EV setup you will likely still need to integrate some portion of the body harness and fool the rest of the car. Bolting in the crate EV parts will be pretty trivial, the wiring etc is going to take time.
A smart company will come around one day with a targeted selection of cars for a "plug and play" wiring harnesses and control units.
A hybrid conversion would be ideal, if this motor could also act as a generator. It seems like it's small enough to fit on the tailshaft of a regular transmission; or perhaps even several of them.
I think that amount of power, although for only 20s, would make for a fun Tesla-beating hybrid sleeper.
The problem is not the engine, it's finding a place to securely mount the batteries that won't interfere with the crash safety systems. Hint: that would cost tens or hundreds of millions per car model if it's even possible. Conversions aren't going to be mass market.
perhaps batteries as we know them today may be different in a couple of years. hydrogen fuel cell batteries hold promise in this regard and possibly others like salt based batteries.
tl;dw: It's much more involved than simply swapping the motor. You need to create a custom mounting bracket for the electric motor, you need batteries (used long-range 75 KwH Tesla batteries go for about $10k), you need a charging system, an electronic management system, and you need to find a way to power peripherals like A/C which are typically powered via a serpentine belt from an ICE.
In time there will be a 3rd party market for conversion kits from EV parts to old cars just like there is a huge market for frames and engines etc for classic cars today.
one would think & hope small well designed motors would & could also be economical to build. there's probably intense process to produce these but how fancy do you need to get with 200kg of materials?
whether material or production costs dominate is an interesting question.
Permanent magnet motors sometimes use rare-earths. It's not absolutely necessary, but going without may lose some power and/or increase the weight. Induction motors don't need permanent magnets, but they're less efficient so the EV industry seems to be moving away from them. (Less efficient also means they generate more heat, which means more active cooling.)
EV motors often have absurdly high RPM limits, which may require some exotic materials and/or lubricants. (I think Tesla motors go up to about 18,000 rpm if memory serves.)
Copper for the windings is another high-cost material; copper has been expensive lately. You could use aluminum instead, but it would mean having to scale up the design or run at a lower power to compensate for the wire resistance.
I do hope to see good, cheap, powerful motors be a thing that was more available to random third parties to swap into their old ICE vehicles. Right now the best options seem to be to use something like a Netgain Hyper9, or scavange a drive unit out of something like a Leaf or Bolt or Tesla.
ok so based off your first three paragraphs what could justify all these mainstream car makers building motors that weigh 2.5X, use so so so much more material? why is Koenigsegg alone able to achieve such material efficiency, when it seems like we should be so pushed to push weight/material usage down down down? what justified such a high power density motor being so expensive?
For an electric car, the hardest part to design is the battery. It's really expensive, and really heavy. If you spend a ton of engineering effort to make your engine 50% smaller and $500 more expensive, all you've done is lowered your profit margin for a tiny decrease in weight. If you instead put the same engineering effort into the battery and manage to make it 5% smaller, you get a bigger weight reduction for the car, and it's probably accompanied with a lower price.
Optimizing things that aren't a bottleneck is almost never a good use of resources.
Yeah, that makes sense. EVs need motors and someone has to make them. Manufacturers will buy whatever has the best specs for the least cost that matches the vehicle. Some companies will naturally specialize on motors, even though motors are basically good enough already.
If this smaller motor is also cheaper because it uses less material that would be a win, but I suspect that's probably not the case. They also don't mention efficiency in the article, and that can be more important than size/weight.
I wonder how much Tesla pays for their motors. I wonder how much they'd save if they only needed 1/3rd as much material.
This kind of material-minimizing innovation seems like it could go a long way. It feels like if someone wanted to mass produce power-dense electric motors, they could radically reduce the cost of a motor by simply using less materials. If they can get to scale. If they can sell them like crazy, which they should, since they should be cheaper to make, as the material inputs are so much less.
Koenigsegg of course doesn't care about production costs. It's expected that every item that goes into the car is going to be built via the most exorbinant processes possible. But the underlying idea of using far less material to make a motor sounds extremely attractive to me.
I didn't see much in the article about efficiency. Koenigsegg seems focused on supercar performance like acceleration, but most EV makers care about range. EV makers do pay a lot of attention to their motors and highly optimize them for the specs that they care about.
The more efficient your motor is, the more mileage you get out of your battery, so the smaller your battery can be. It could easily be that an extra 1 kg of steel and copper shaves off 10 kg of lithium ion batteries.
The Netgain motors are wildly outdated. 100-140v in a world where 400v is almost standard, and 800v is increasingly common.
Means you need very heavy duty wiring/controllers, high current rated batteries, can't use OEM power steering / AC compressors, can't use OEM battery packs, can't use DCFC infrastructure....
And why not? Power steering systems don't run on the HV system but on the LV system as every electric car has a DC/DC converter that bridges the HV and LV domains. So regardless if your cars is using 800V or 100V powertrain system, all the auxiliary equipment will still be on the 12V network.
I basically agree with that, though I'd say that lower voltage motors are sometimes useful in conversions, since they usually have a smaller battery pack than what would be in an OEM vehicle (due to weight, cost, and having limited space to put the battery). Lower voltage doesn't really stop you from salvaging all those other parts from an OEM vehicle. I think it's usually just the motor controller and DC-DC converter that run at the full pack voltage. DC fast charging is a problem if the charger doesn't support the lower voltage.
I have wondered whether the Hyper9 can actually run at a higher voltage without damage. I suppose the limiting factors are the insulation on the motor windings and the ability to dissipate heat. (The motor demagnetizes if it gets too hot, which is why the motor has a temperature sensor so the controller can back off before that happens.) The Hyper9 comes with a motor controller that's limited to 180 volts (that's for the 144v nominal version). I don't know if anyone's tried to run a Hyper9 with a different controller that can handle much higher voltage, like 300 or 400v.
They finally did it, I remember on YouTube watching videos of a man at some kind of trade show who claimed you could build car motors that were roughly the size of a soup can and far more friendly for the environment. Always thought he was a crank, but I guess not.
Scaling the weight linearly down to a soup can (1/63) gives you about 5 horsepower. The Model-T had 20 horsepower though, as does your typical riding lawn mower. So you'd have to soup it up a bit more than that.
Motor torque capability generally scales in proportion to volume, but shaft speed capability typically increases as the motor shrinks, so the motor power will usually fall at a smaller rate. A motor with 1/64 volume will probably output between 1/30th and 1/16th of its power. So 20 horsepower might barely be achievable. It all really depends on the driver though.
Why don't you see a lot of very long thin, high revving motors for higher power with smaller size than large motors? This one has completely the opposite scale of dimensions even.
So, mainly two reasons that I am aware of. First, with a long spindly motor running at high speeds, eventually shaft whip becomes an issue; the distance between the bearings ends up being really far. Second, designers usually want low-speed torque more than super-high-speed power, and at high diameters you get a bit more torque than small long motors of equal volume, because torque scales more like the volume of a somewhat hollow cylinder rather than a fully solid cylinder.
For most brushless motors--though not axial flux motors like the one under consideration here--it's much easier to get heat out by passing air axially across the stator. This means that while the surface area is increasing proportionally with length, your ability to flow air across that surface area is not keeping up. For that same motor volume, a shorter and fatter motor will have better airflow and cooling than a long skinny motor.
I have a motor the size of a film canister that produces 0.5HP. It was built in 2003. I'm sure with better magnets and scaling to the size of a soup can would get it well above 5HP. The main caveat is that it spins at 20k RPM, so it would need a gearbox.
You can already get a soup-can sized 3.5kw motor on Amazon for ~$100, so that exists already. Their tech might be optimized for the size motor, but if not, there might be room for improvement at the smaller size.
Since the Ami is a car that actually makes a little sense for cities, it probably counts as "clown car" for people who are used to the huge hunks of steel that you usually see on streets.
Yep, though "clown car" seems dismissive, maybe we could call it "sort of legal for the road golf cart", as it does makes lot of sense for some EU city centres or for local deliveries in places where streets and parking spaces are tiny.
I saw a comment a few years ago from a guy that claimed to design electric motors. He said the design space is pretty hashed out. But what's changing is controls and use cases.
That said I think rocket lab gets 50hp out of the soup can sized motor they use for their turbo pumps.
It mostly is, but way at the boundaries of performance where cost is no object, I wouldn't be surprised to see a company like Koenigsegg advance beyond normal limits, using pricey materials like cobalt steels, sintered powdered iron, phase-change cooling, or other tricks that are beyond mortal budgets.
I always do a quick fact-check on any automotive engine claim:
HP & Torque curves vs RPM should always cross at 5252 RPM.
The one in TFA does not.
\_(ツ)_/¯
> HP & Torque curves vs RPM should always cross at 5252 RPM
Not really. First, this number only applies to imperial units. Second, axis scaling will move the crossing point. The only way this happens (provided we are talking about imperial units) is if the torque and power axis scales are explicitly scales such that the curves intersect at 5252 RPM.
It keeps surprising me that “you Americans” are still not using the SI system. As an European, it feels like I am reading an article from 1830, with hp instead of kW and lb-ft instead of Nm.
But - out of curiosity - why is the soda can measured in ml and not in fl oz?
I was always tought that the liter was an SI unit, I mean, it's defined in terms of SI units, I know it's not a base unit, but weird that it's singled out as "well, you're technically SI compatible, and you're defined in SI units, but we're not gonna let you be part of the group" :)
It even has an official SI symbol (L), despite not being an SI unit, what?!
I'm European and think in horsepower, not kW. Because I was born 40+ yrs ago. So what?
It's basically just a linear conversion of kw = .75 x hp anyway. What's the huge advantage here?
I'm all for metric or SI. But let's not overstate the value please.
The advantage is not having to remember all those funny constants and being able to do math in your head that actually makes sense?
Or more important, to be able to write an article that the entire planet can just read without 95% of them (everybody outside the US, UK and Myanmar) having to resort to Google to find out if those numbers are impressive or not?
Good addition / correction. So the amount of people that is unable to follow the article without too much effort went down from 95% to 80% of the audience.
It isn't funny because the GP doesn't want SI units to be used because they are a standard but because 95% of the world can understand them. I'm certain that more than 95% of people understand years.
This sounds like it is directed at me and I don't see why. Humor is often dependent on context. Some jokes are funny in some situations and not in others. The above joke is not funny here since it entirely misses the context in which it should be used.
I think the point was that horsepower is widely understandable and preferred in Europe as a unit of an engine power, despite otherwise using the SI units.
Horsepower is different though, you have imperial horsepower and metric horsepower (and many more). Both are not the same and neither is a round 750 watts.
For the last years I’ve mostly seen watts being used in NL, but it’s been ages since I saw a fast and furious movie or a top gear show. The car sellers use kW and often also, I assume metric, horsepower.
>The advantage is not having to remember all those funny constants
This, very much! I've done a ton of physical simulation code in my life. Whenever some newb or student comes to me for the first time with their simulation code that mysteriously doesn't work, in 90% of cases they stupidly didn't stick to SI and forked up some unit conversion, or mutiple. I tell the to keep it in SI and never let me see them make that mistake again. (Only exception is simple 1-to-1 unit conversions of parameters and results, when some stupid interface definition demands it that can't easily be changed.)
1. Everything uses a common base, so you don't get a base change on a scale change (or indeed, two different bases for different parts of the same measurement), and dimensional consistency becomes trivial.
2. The base is base-10, which is the same as our common counting system.
There are two exceptions I’m aware of to “SI is easier in practice”.
1. Temperature. It’s useful to elongate units over the range normally experienced by humans, which Fahrenheit does and Celsius does not, because it avoids tenths of a degree, for example, in room temperature selection.
2. Woodworking and similar: it’s useful to use powers of two because it’s very common to be marking/cutting/etc. 1/2 or 2x a value, which is easier to do in inverse power of two English measurements.
I've found metric to be better for woodworking, and especially metalworking. Powers of two (imperial) are no easier than doubling a metric measurement, and more difficult when partitioning items items in thirds or fourths, or having to cut wood in half with lengths like 56 and 7/32 inches (1428mm).
Horsepower is not horsepower. American "HP" is not the same as the horsepower (PS, pferdestärke) we use in Europe when we talk about "horsepower".
a kW is always 1000 watt, not 992.3 watts because of course it's a Canadian kW.
I personally decided to just use them always for clarity and I saw few people around me catch on. Be the change you want to see, especially when it comes to the free minor stuff.
Kibi didn't exist until 1998 (per your link), so anything you read that was written prior to that and for a few years after still has the kilo=1000/1024 ambiguity.
Computer people speak in Base 2 units because that's how the devices operate at a low level.
After many years and different widths the smallest common unit of exchange evolved to be a power of two: 8 bits are a byte, not 9, 10, 27, 30, etc; though Unicode might have been better off if 32 bits were the base character. However then older systems would have been at least 75% less useful.
Physical addressing units are also binary, because literal address lines (or their virtually latched equivalents on a serial bit-shift register) are used.
ROM, RAM, and correspondingly non-volatile writable storage inherit this basic premise.
So a non-sales computer person speaking 'kilo' or 'mega' or any other SI unit in relation to a computer part means it will hold or be able to transfer at least that many SI units in the quoted units. Everything gets rounded to the nearest useful neighbor. A digital kilo is not 1000, it is 2^10. A digital mega is correspondingly also 2^20. This is very similar to the exponents in SI units.
For that matter, humans have 8 fingers and 2 thumbs. Wouldn't an octal numbering system make more sense? Though for that we'd have to come up with new unit names near 2^3, 2^6, 2^9, etc that don't sound silly.
> For that matter, humans have 8 fingers and 2 thumbs. Wouldn't an octal numbering system make more sense? Though for that we'd have to come up with new unit names near 2^3, 2^6, 2^9, etc that don't sound silly.
Each of the 4 long fingers has 3 phalanges, so an interesting possibility is to use each thumb to count up to 12 on each hand. Given that many ancient units of measurement where base-12, I wonder why we didn't develop base-12 languages.
I've heard that's how merchants used to count in the Mediterranean. However much like QLC and TLC SSDs are more finicky to work and require stricter discipline than simple on/off storage, the same can be said for fingers and is it up or down.
That make me curious to look up the Koenigsegg's power. It would seem they are metric horsepower:
>Two common definitions used today are the mechanical horsepower (or imperial horsepower), which is about 745.7 watts and the metric horsepower, which is approximately 735.5 watts.
I guess speaking as a Brit the foreigners just didn't have proper horses.
Same. Screens and wheels are still 100% described in inches in sales.
Cars are specified with HP and optionally kW. Never kW alone.
Outside of these weird exceptions, it's SI all the way. And this doesn't really vary with age. The web site whrere you buy wheels and TVs doesn't know your age so it will say the rims or screens are 20" regardless of who you are.
Calories, grit, carats (for diamonds), Beaufort, viscocity is of ten boven in cP, grit (based on inches), dernier, rpm, dpi, lightyears, and of course km/hr. Plenty of non-SI units in use
Yes. I meant metric and sloppily said "SI" despite most common metric units only occasionally being SI.
Beaufort is a dimensionless label as far as I'm aware and grit is used as such too (i.e. it never says anything else than "240" i.e. it doesn't "240 grit" or "240 something per inch").
Grit is based on the amount of particles that fit through an inch square. You could also indicate it with the particle size inmicrometers.
My list wasn't close to exhaustive. We use all kinds of weird units.
Besides bar I sometimes see mmHg for pressure. Shoe sizes. I've never seen acceleration in m/s2 outside a physics problem, otherwise it's either G or seconds to 100 km/hr.
> We use all kinds of weird units.
> Grit is based on the amount of particles that fit through an inch square.
I'm aware. But I'd say its mostly used as a dimensionless. When I argue "we use metric except for these few" I mean in the cases where the unit (a length, mass, pressure etc) is actually uttered or written.
In some cases as you note there are labels which have non-metric definitions underneath, such as sand paper particles having a never-pronounced inch definition. The same goes for some weapon calibers where you might say a ".303 cartrige" for rifle ammunition but you'd never say a ".303 inch cartidge". A lot of people probably use these labels without knowing they are using an imperial definition. And that (I'm guessing) is also part of why it survived the metrification.
> I've never seen acceleration in m/s2 outside a physics problem, otherwise it's either G or seconds to 100 km/hr.
"10s to 100km/h" is as metric as m/s2 though (But again not pure SI).
g being a constant obviously has no explicit unit, it's as metric as you want it to be :) I hear "5g" as 5x9.82m/s2 but an american probably hears something else.
There's more nuance to it though: if you take a closer look at fields where inch are used even in fully metric language environments you'll find that it's often more a class designation than a measurement. A 21 foot container does not exist (turns out that according to the wiki 20 foot containers aren't even allowed to be 20 foot long, they are 40/2 minus some defined amount of padding)
It's even more pronounced with camera sensors, the size given in fractions of an inch is some kind of "equivalent to", whereas the size in mm is the actual size. Apparently the image sensor inch is 16mm or something like that.
I was surprised during NASA's first commentary session of the WEBB telescope launch. It seemed like it was the first time when they were consistently using SI units while speaking to their US audience. I think one time an imperial unit slipped out, but it got corrected immediately.
Immigration from Latin America and Asia are certainly helping SI in the US. However, there is a loooooong way ahead... And forget about Celsius, this one is nowhere to be seen.
(US here). It kind of helps to think of celsius between 0-100 as “percent of boiling water” for me. Living in one of the hotter parts of the world at the time, being able to say the temperature is 40-50% of the way to boiling water really seems a good objective definition of “too hot.”
Technically 0F is the freezing point of water, just a different type of water.
As a European I find Fahrenheit kind of makes sense on a human scale as 0 and 100 are the upper and lower limits of it being reasonable to be outside. Below 0 is "too cold", above 100 is "too warm" and when it is 50 it is neither warm or cold.
"Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride (a salt)."
It's funny to use that rationalization regarding 0-100 when in reality the rest of the Imperial system is utterly allergic to that sort of scale. 0F and 100F being endpoints for "reasonable" seems a bit of a stretch as well. As a Canadian that's "reasonably cold" and "way too warm".
I can't believe that there were people who actively worked on killing this effort and actually succeeded. Talk about stupidly reactionary.
In general it seems US public policy has suffered since the 70s. There were things like serious efforts for universal health care or metric conversion. These days it's not even imaginable to make a big change in the country.
> The Metre Convention (French: Convention du Mètre), also known as the Treaty of the Metre,[1] is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Ottoman Empire, United States of America, and Venezuela).
I didn't seem that way for their online tracker. Every time you visited the website you have to manual switch it back to SI units as the default was not SI.
Imperial units are often tied to measurement devices or operations of a device, than just being a collection of odd standards.
A passenger jet can attempt a landing on a 3000 feet long runway from 4 nautical miles from touchdown point, flying 250 knots at 1500 feet. Altimeters must be calibrated to announced local atmospheric pressure, or the default to 29.92 inHg or 1013 hPa.
Autoclave is a device used for sterilization that exploits saturated(pressure equal to ambient) steam. It is usually ran for 15 minutes at 121C(250F). According to a random internet source[1], atmospheric pressure at sea level is around 15 psi, and 250F is the point where pressure of steam exceeds that, being a function of temperature.
(One of) the beauty of SI units is measurement devices itself are universally built and marked in SI units that disparate measurements across industries can be converted and compared against. There is no “3000 feet runway 4 miles away” in metric, it’s a 1km runway 6.5km away. There is no need to convert between inHg and feet and PSI, or lb-ft and inch-pounds just because F.G. Superman in 1337 who pioneered art of bicycle repairing set measurement and tolerance for a bike frame to be 50 +/- 3.5 inch-yard per fortnight centigrade.
But that requires phenomena to be well studied and measurements clearly defined against SI units, which is a point more industries than we care to admit has reached.
That has to be an aspect of why imperial units persist, despite NASA and cutting edge aerospace are moving away from it, other than there would be a simple matter of gross widespread ignorance.
You mentioned nautical miles. Originally, the nautical mile was defined as 1/60th of a degree of longitude (aka one minute) along the surface of the sea, and so it is a pretty natural unit from a navigational standpoint.
It has since been redefined based on that original definition, as 1852 meters.
So it’s a goofy measure in that it uses base-60, but is otherwise more in the SI family both in terms of original derivation from natural measurements and in terms of its current SI-based definition.
There are other things out there called a “mile” that aren’t imperial, too. Take care when asking for directions in the Norwegian countryside, for example: https://en.m.wikipedia.org/wiki/Scandinavian_mile
Originally, a meter was defined as 1/10,000,000 of the distance between the equator and the North Pole. The circumference of the earth is now 40,075.017 km instead of 40,000 km but it was a pretty good estimate for 1795.
It's so annoying. They have the screen real-estate to show both units, but for some reason it's like they're trying make a very subtle statement to their international audience. "For Americans only" or something like that.
I don't see why you are being downvoted, you are absolutely right. For example you have US Gallons and Imperial Gallons, with the Imperial ones being used in UK not US.
Yep, and those two gallons aren't even remotely close. It's the most annoying thing on car forums, because someone will always say "oh my car gets 30mpg but everyone here says they are getting 40mpg!"
Like, yes, because you haven't established whether they mean US MPG or Imperial MPG.
YES! I always assume ( and very stupid of me ) that it was some regulation with cars and the way they drive between US and UK making some difference in MPG. I never knew the G in mpg was different!
This is one of the illustration with online or even real world discussions where we argue pass each other under the wrong basic assumption.
Yes, it's funny that when the standard unit is a somewhat lower number (so the KW number is the same magnitude but just a bit lower / less impressive than in HP) there is more resistance to the change.
I think in EU it is mostly due to the German car industry (and all the associated publications) unwilling to change.
In the German speaking world everyone knows what a hp is (PS), how much his car has, his past cars had, in which configurations their car is available... although the kW is what is printed on the documents since ages now.
Nobody likes change. Some people still complain about the Euro, and that the DM was so much better... At least it is not called ECU.
I'd dispute that. Everybody can roughly imagine a 1/4 multitude of the 2.5 kW of a typical hairdryer, nobody has a meaningful mental image of the amount of continuous work one could expect rotating a number horses (peak power per horse is about 15 hp)
But seriously, I do like the split-phase power we have in the US. I think we get the best of both worlds, having lower voltages in most living spaces, and higher voltages reserved for high-power appliances.
>>I think we get the best of both worlds, having lower voltages in most living spaces
How is this possibly a benefit for anything though. It's not like 110V is safer in any practical way, if you stick something in a socket it will kill you just as much as 220V would, so it seems like for literally no reason at all American homes have a much less "ability" to support a wide range of devices that work without any issue elsewhere in the world.
It's safer because of ohms law. Anything you short it with (whether that be an object that might heat up, or a human) will pass half the current and a quarter of the power.
I've been shocked with 120v on bare skin multiple times.
Yes, but my point is that it's still just as deadly for a human. It's like asking whether you want to be in a plane crash going 300mph or 600mph - it doesn't really matter. The #1 improvement in home safety when it comes to the electrical system is the socket design to prevent foreign objects entering(like the British plug design for instance), and second one is a working RCB fuse to kill the power before you even feel a tingle. 110V or 220V doesn't really matter.
Crashing at 300mph is guaranteed deadly. Being shocked with 120v is not. I've been shocked a half-dozen times and I haven't been injured in any way.
Current code in US/Canada also requires RCDs (we call them GFCI) in some places (and AFCI everywhere, which the rest of the world hasn't really adopted) and shuttered outlets... but these do not catch all types of faults. For instance, if a human conducts electricity across two conductors connected to an RCD/GFCI, it won't trip. It only trips if current is drawn to ground or to another circuit. Layered safety is a good approach.
That's not to say that 240v systems are unsafe -- they just have different characteristics and requirements because of it.
Yeah I've been shocked a few times with 240v and it's not nice but doesn't often kill people. Most electricity caused deaths are from something causing a fire rather than shocks I think.
This is so true! Fortunately, for BEV we seem to switch and this works incredibly well. You see kW and you know its about electrics, you see HP (or rather: PS) and you know it's about one of those wonky old "explosions in a tincan" things that eventually displaced the horse. It's quite powerful linguistic era demarcation.
When communicating in English with the intent to be understood it is wise to include both, putting the conversion in parens. I’m always thankful when Americans include this - otherwise all those feet and pounds and inches and stone are just random numbers to me.
I just remember that 1hp is 754 watts, but lets just call it 750. Another magic conversion that I remember from working on that stuff is that Nm * RPM / 9549 = kW. We never used ft-lbs though.
kW*h is the unit that absolutely kills me. Especially because people will just say "kW". And before long they're talking about "kW*h per day"... Kills me. "What do you people have against James Prescott Joule?!"
The prefixes with Joules get bigger. 1kWh is 3.6MJ. G and T are rare outside data sizes, it's nice if everything can stay in the milli through kilo prefix range.
SI isn't being used for real in Europe either. Highway speed limits there are always in kilometers per hour, instead of the SI units of meters per second as used for spacecraft. Heh.
Expressing quantities in SI units doesn't require 'base units'. SI prefixes are permitted (milli, micro, kilo, mega...), as are certain exclusions (including minutes, hours, ...).
And why the heck do sockets and drives come in negative powers of 2 such as 1/2", 1/4", 1/8" whereas smaller tolerances come in 1/1000's of an inch? Why not 1/512" and 1/1024" ? This gets into awkward conversions even within the imperial units such as 5/8" into decimal 0.625" instead of something like 640/1024" because of no good reason :-/
Why does it matter though? They're used for different orders of magnitude. I've never understood why people think that having everything in multiples of 1000 (as the metric system does) is an advantage. Yes it's easy to say how many millimetres there are in a kilometer. But when was the last time that came in handy?
That said, I think the US car industry has moved to metric and it is great to not need multiple sets of everything.
What about if it isn't water you are calculating but some other substance? You use a look up table to find the factors - we need to look up a but more in the table, but it isn't a big deal.
Are you serious, they literally just gave you an example lol.
I always hear that argument about "but when will I need it?" If you're using this system then you're always going to use it. It comes up all the time, it's natural so you don't think about it too much.
Does it mean it's better? Well yes, but it doesn't mean other measuring systems aren't good. You don't need it, but you'll want it once you learn it.
The first is a real example from a friend whose drains were blocked during some construction work, where rainfall from his garden was running into his basement during a storm. Would the water reach the electric cables?
The second is obviously relevant for the people responsible for rivers, storm drains, sewers, dams, hydropower and so on. When we start terraforming Venus, we'll need to add the conversion factor for sulphuric acid rain.
The ease is in moving between measurements. How many feet are in 102.3 inches?
Sure I can do the math to calculate it in my head and take a few seconds.
How many meters are in 240cm? Don't need to 'calculate' it the same method. I just move the decimal over. 2.4m...
I say this as an American who finds our use of Imperial pointless. Infact, there is a highway in Arizona that uses metric instead of imperial, as it was a part of our move to metric. (The current measuring and weights system in the United States is based on Metric, we do use it, just converted into another measure)
Every time I need to add or subtract two measurements.
Quick:
What is 2' 3 5/8" plus or minus 1' 2 19/32"?
or
What is 701.7 mm plus or minus 370.7 mm?
Seriously I work with both everyday, and while I grew up with inches & feet and I still intuitively know how deep two feet of snow is better than 61 cm of snow, I'm really starting to hate the US measurements, and use metric whenever I can.
Also, whenever we deal with things from the rest of the world, it becomes a mashup of US and metric measurements.
The US almost converted to metric in the 1970s, but Nixon squashed it, basically on the complaints of what are surely the ancestors of modern US right wing know-nothings who didn't like "foreign" stuff.
Looking at it historically, the fractions made a lot of sense when things were more coarse, and the ability to split things into even sections, 1/2, 1/3, 1/4... was more common.
OTOH, Metric was designed for doing calculations - we already use the decimal system for all other math, so we should design a measuring system to use the same calculation system. It really does work better.
well, a lot of people don't use SAE sockets for serious stuff. Your IKEA chair might have some 9/16ths wrenches - but for cars and other mechanicals its mostly metric.
A few brake lines and some old exhaust bits might be SAE, but by and large vehicles are done with metric.
Personally I like that SAE has fewer sizes... Its frustrating as hell working on cars with a mixmatch of 6mm 7mm and 8mm bolts. oh this is a 15 but a few awkward 16s! Mostly though, cars are pretty standard. European cars seem to be basically - 7mm 8mm (hose clamps and other tiny stuff) 10mm (air filter housings and such where 8mm is to small) 12mm 13mm (misc bolts, intake manifolds, exhaust, almost everything) 15mm 17mm 19mm (these larger ones are basically suspension and other large components)
England is a strange combination of metric and imperial. Walking is measured in km but driving is miles. Weight of a person is stone and lbs, but of any other object is in kg and g. Height of a person is ft and inches, but of any object is in m, cm or mm. It's very odd
When my baby was born about a year ago here in UK I would always say his weight in kg when someone asked, and people would literally stare me blank in the face and say they have no idea if that's a lot or not. Once I converted it to pounds for them they were like "oh yeah, he's a big baby then".
It's not that great a motor design. It's good, but we had similar power to weight motors where I worked 10 years ago and could run 200kW for more than 20 seconds. Good motor designs are cool, but IMHO they are usually not news-worthy but are just marketing.
> But - out of curiosity - why is the soda can measured in ml and not in fl oz?
The article is written for an American magazine while the pictures are from Koenigsegg directly, which are European; beverages use ml and l to measure contents.
Take a look at the graph, also provided by Koenigsegg, it uses Nm and kW.
If you want to see something fun, go check the size of the tires on your car (printed on the wall of the tire). It will read something like "245/35R18", where 245 is the section width in millimeters and 18 is the diameter in inches. All standard tire sizes use a combination of inches and millimeters, haha.
it gets worse the more you dig in. The middle number is am aspect ratio for length of sidewall. so its side wall thickness 35% of 245mm. Then on top of that when youre getting into trucks and jeeps common sizing switches to inches. so you go from 315/70/R18 to something like 35x12.5r18
>>As an European, it feels like I am reading an article from 1830, with hp instead of kW
Where in Europe are you that anyone uses kW for engine power lol. Yes it's listed in kW on my registration document but I've literally never heard anyone using kilowatts to describe engine power instead of horsepower, and I lived in a few European countries so far.
I’m in the Netherlands. I just did a Google search for electric cars and checked the top 3 results (Polestar, Hyundai Ionic, Mini) and all three of them list the kW numbers first / large and then the pk number between brackets or small. So we can safely assume that kW is dominant where I am.
Yeah, it's a pain point for me as well. We try to do all of our design work in SI units, use metric screw, etc. The problem is that industry simply isn't aligned this way. Sometimes you end-up with such a mess that you are forced to go back to imperial just for sanity.
The problem with switching the US to the metric system is that the cost would be truly massive. It would take decades, somewhere in the order of 50 years, for a complete conversion.
There's the obvious, things like every single highway sign would have to be replaced. And then there's everything else, like every single tool that everyone owns in this country would have to be replaced at some point. You would still have to be able to buy and use imperial unit hardware and tools for decades during and likely after the transition. I can't possibly list just how deep and wide such a conversion would have to reach.
And that's assuming everyone goes along for the ride. That said, a 50 year timeline would mean a new generation would grow up using the metric system. Another 25 years after that and we should be OK.
All of that said, the real problem is political. The cost of such a transition would be significant. Politicians will only get behind things they can convert into votes. Going metric isn't one of these things. Spending billions of dollars over five decades isn't something anyone can use to win an election. Most people aren't close enough to the design and manufacturing of goods to understand just how much this system actually hurts us. And so, going metric, in a practical sense, becomes an impossible dream.
The Farenheit temperature scale makes a little bit more sense to me then the Celsius one. It covers the temperatures we care about in more or less temperate climate, with 0°F being the lowest temperatures one will witness (-32C) and 100°F the highest (38°C), the latter being also a body temperature above which one has to worry about.
The Europeans are also still not using the SI system for measuring clothes or shoes. Actually I believe clothes and shoe sizes are a much bigger mess between all the countries in Europe than in the US. It is strange that the bureaucrats of the EU have not tried to a least unify these sizes, let alone using metric units.
for 95% efficient 200kw motor you'd need to dissipate 10kw. Doing it with air is problematic, and usually motors like this are water/oil cooled, otherwise it is really limited to short sub-minute burst of full power.
At this rate I would not be half surprised to see in-wheel type hubmotors as used in some electric skateboards [1] or the OneWheel [2]. That kind of changes the whole drive train concept.
It's unlikely. Anything attached to the wheels is "unsprung mass", and it has a huge effect on the handling and comfort of a car. Furthermore, for efficiency, you really want to minimize rotational inertia in the wheels.
Sure, for slow vehicles where these things don't matter, hub motors work great, but not for your typical road going car. They could put one of these near each wheel and drive the wheels via axles.
I don't think there are any losses on a (reasonably short, i.e. without intermediate supports) axle transmission, the only form of attrition are bearings and on both sides of such a setup you need one anyway, unless the same bearing is common between the wheel hub and the motor (i.e. the motor is actually the hub).
Could you elaborate a bit more? Do I understand correctly that in today’s world of energy efficiency, the car’s mass distribution has to be carefully tuned for maximum efficiency, and hub motors throw that off balance?
Intuitively, I always figured that having mass on an object that’s very low to the ground is a good thing, but I can imagine it’s something different when it’s attached to a wheel.
Apart from the mass distribution, if you look at a car travelling on an uneven road from the reference point of the car itself, you will see the wheels moving up and down very quickly to keep contact with the ground. My understanding is that adding mass to the wheels will slow them down and thus increase the time they don't touch the ground, reducing the grip.
F=ma, so if you increase the mass you either decrease the acceleration (they slow down) or increase the force (they hit the bumps harder). In practice it's both. The vertical acceleration when you hit a bump is essentially determined just by your speed and the size of the bump; it can't be slowed down. So instead what happens is the bump will exert a greater force on the tire (which will deform it more, reducing grip and probably meaning you'll need to run higher pressure, which also tends to reduce grip). On the other side, when you leave the bump, the force is determined by the spring rate of the suspension and the amount of compression, so for the same suspension, a heavier wheel will move back to the ground slower, which yes, will reduce grip. You could increase the spring rate to compensate, but that would exacerbate the first problem, and also wouldn't help in the situation where you hit a dip from steady state rather than exiting a bump.
The purpose of the car's suspension - the springs and shocks - is to decouple mass from the wheels. This allows the wheels to travel up and down over bumps and dips in the road surface quickly without large forces being exerted, which in turn makes for a smooth ride and good traction between tire and pavement. The more weight you move from the 'sprung' part of the vehicle - everything that's suspended by the springs - to the 'unspring' part - directly connected to the wheels - the more this is compromised. You can think of the extreme case where you take all the vehicle's weight and move it to the wheels: then it's like you don't have suspension at all and you're bumping and jarring across every imperfection in the pavement. Moving a lesser amount of mass to the wheels is basically a lesser version of that. (Likewise anything you can do to reduce unsprung weight - lighter brakes, wheels, tires, etc. - tends to have an outsized effect on handling. (And on performance in the case of rotational weight, but that's a separate issue.))
This made me think of that peculiar vehicle where the wheel is massive and the driver sits inside. Can't remember what it's called now but I seem to remember a spoof version in South Park.
Think about going over a bump. This gives the wheel a strong upward motion. The suspension has the task to discouple that motion from the car. Which is easier, as much as the wheel mass is low compared to the cars mass. Thus the aim is to keep the wheel as light as possible.
It might be worth mentioning that “because unsprung weight” argument is a chassis design argument, not a powertrain one. It applies to all engine types, including electric, gasoline, diesel, and steam engines.
I would not discount it completely. If you need only 20kW per wheel (for a typical european car) maybe then electric motor ends up actually lighter than classical axle setup? Perhaps even more so if also replacing brakes, but I don't expect that to happen soon.
Electric Wheel motors have been used before. The LeTourneau had an electric wheel back in the 1950s. This was IIRC mainly used for Earth moving equipment though.
They probably don't make sense on cars though as explained by other people here.
So it does. I was recalling Porsche lore from memory and thought I had a correct reference. Iirc Porsche built an electric 4-motor (hub) car for the Paris Expo about this time…
Oh, here we go:
> In 1900, at the Paris Exposition Universelle…[0]
Impressive, but they are probably optimizing purely for burst power, not for efficiency, making the trick easier, because the car has an ICE delivering the base power. Compared to Tesla, they have to optimize for both power AND efficiency, because their car is running on sole battery power.
Quite right. The small graph in the article confirms it. If you zoom in enough you can see the power and torque are more than doubled during the 20second burst mode, but even so it is very impressive
I think Tesla cars also have a similar "burst" mode too?
Some turbocharged combustion engines also have something called overboost, allowing short periods of operation at higher power than the "continuous" limit (again due to heat build-up)
This might apply for the use in a car having ICE. The electric motor itself could be optimized for efficiency, too. Efficiency adds range and indirectly reduces weight by smaller batteries. To rate the efficiency, we would need more data about motor efficiency vs. loads.
Modern Teslas also can sustain max power as well. Model 3 can basically launch consistently 0-60 in about 3.2sec some 20-30 times with no loss. The new Plaid can do low 9s back to back until the battery is low. Quite an achievement.
I know this is meant to be a joke but knowing folks that work in said department this is only true of engineering cars. They aren't able to do whatever they want with their own production cars.
The TLDR is production cars are "fused" at the factory to only work with firmware signed for production vehicles and devs can't produce these production builds themselves. There is facilities for live patching production cars but these systems are even more restrictive.
On the other hand... all bets are off in an engineering car. :P
I believe this was mostly on the older Model S that didn't have a dedicated coolant pump. It would always run at a fixed speed which was fine for normal usage but not on the track. New Tesla's have added a dedicated small electric pump so it can run at the speed needed to keep the motor in the correct temp range.
I'm sure they can still overheat based on other limitations (coolant radiator, pipe size etc...) but these can be rights sized based on trim level.
If my back of the envelope calculations are correct, our 7-seater midsize SUV uses about 35hp at a sustained crusing speed of 70mph. For a road car being able to produce it's maximum power for only short periods isn't much of a problem.
Slightly different if you expect to be able to take it around a track.
I'm having some issues here with the scale. With "For scale, that's a 330-mL energy drink", do they mean that it has a diameter of around 13 cm or what?
Also, aren't energy drink cans larger than coke cans? I haven't had a can in front of me for years, so using cm (or inches) would have been better.
"small Red Bull can". I didn't know they come in different sizes. Apparently the small one is 250 ml, mid one 355 ml and then there's a big one of 473 ml.
The 250 ml comes in a 14 cm height box, so I guess the 13 cm were a correct guess?
A 330 ml "Sleek Can", which I guess is the same one as a Red Bull can, has a height of 146 mm.
You know there's some scientists who study shapes and they say that diameter and height are different properties of a cylinder. I wouldn't know anything about that though I'm certainly no scientist.
It's the article which is comparing the height of a can to the radius or diameter of the motor (apparently the radius, but it would be more logical to compare it to the diameter).
It's just as valid as using bananas for scale, but the issue with the article is that that it doesn't even bother to mention the actual dimensions in cm or inches, yet it uses "tiny" in the title to describe the engine.
But for a circular cylinder, the height is not the same as the diameter, which of course is taken as the widest length across the circular cross-section. For a standard energy drink style can, that is around 70 mm (less than 3 inches).
> For scale, that's a 330-mL energy drink", do they mean that it has a diameter of around 13 cm or what?
It just means it's a standard european small-but-tall style can. There are 2shapes of 330ml cans, the shorter/stubbier one and the taller narrower one which was initially most common in energy drinks but is now used for soda cans too. Beer still uses the shorter/stubbier 330ml.
I believe they are around 14.5 cm high. Diameter around 6cm.
It's good that people are getting the weight down of these motors, but i'm still unsure why I need 250kW+, let alone two of them built into the drivetrain.
I've managed with <100kW for the last 30 years in my cars of choice, and I know headline figures sell stuff, but we're trying to save the planet at the moment. But I guess if it convinces petrolheads that there's still fun to be had going electric that serves a purpose...
Not that you're wrong generally speaking, but doesn't Koenigsegg R&D and license technology too? I believe they're trying to license (maybe even manufacture) their freevalve technology to some ICE-based auto manufacturers?
So it's certainly true that most of us here probably aren't the target for Koenigsegg super cars, we might be indirectly consumers of the engines or engine technologies they create.
Koenigsegg has been an incredible company to follow and their CEO is such a pleasure to listen to that they're one of the few auto companies that I'm excited about. I'd be even more excited if they took a path similar to Tesla or Polestar and started offering an affordable brand of EVs.
Unlike internal combustion engines, an oversized (for everyday driving) electric motor is not substantially less efficient in everyday driving than a normal-size one. In fact, oversized components are often more energy efficient (less electrical resistance etc).
i've always had the impression that miniaturization was the key to low thermal dissipation and electric consumption... How is it different with motors ? ( genuine question)
An oversized motor will be slightly less efficient at low load, but only slightly (compared to an IC engine whose efficiency is strongly related to size).
An oversized battery, or oversized wiring, will generally be more efficient due to reduced resistive losses. Larger components (such as are designed to handle high power levels) have lower electrical resistance.
Most of the places where miniaturisation is key to low power consumption are where power is used to process information. In that case, you're trying to get the amount of energy required to handle a bit flying past as small as possible. Most of the energy consumed in this way is used to fill up or empty the capacitance of the "wire" leading from the output of whatever is processing that bit of information, so anything that reduces the capacitance will reduce the power consumption (to a point - you also need to worry about leakage). Miniaturisation reduces that capacitance.
With electric motors, it's completely different - the amount of physical work that comes out of the motor is fixed - you can't reduce it like you can with information processing. So, you're purely looking at improving the efficiency of the conversion from electric power to mechanical power. A larger motor allows you to do that with thicker wires (so less resistance to heat up) and with things moving at a slower speed inside (which also helps). The only downside of a larger motor is if you have to carry it with you - that could reduce your efficiency by making the vehicle heavier. However, electric motors are generally remarkably efficient these days, and the main consequence of the inefficiency is heat generation, which gives us the other advantage of making it bigger - it is easier to dissipate heat from a larger object than a smaller object.
Energy efficiency is usually expressed as a percentage in one of two forms:
1. (useful energy out) / (energy in)
2. (theoretical minimum energy consumption) / (actual energy consumption)
In thermodynamic systems the second is often expressed as "isentropic efficiency" or similar.
In computing the second term can also be expressed using Landauer's limit [0], the theoretical minimum energy consumption of computation. Current computers are still shockingly inefficient in this regard, taking several orders of magnitude more energy usage than the "ideal" minimum.
So really, as inefficient as a gasoline engine is, it's nowhere near as bad as even the smallest, most modern CPU.
"Millions of times" level of inefficiency is like burning banknotes for warmth.
There is one positive environmental aspect of high power electric motors if they are capable of recuperation: you can recuperate a larger portion of the kinetic energy which would be wasted otherwise as heat using breaks. This counts even for heavy cars running lower speeds or not accelerating fast.
Aircraft mostly don't need much torque. And, a reasonable mass of batteries still don't hold enough Joules for a generally useful flight.
So, given a beefy fuel cell and liquified hydrogen tank (bonus points for aerogel insulation), an electric motor optimized for energy efficiency is likely to be more useful than one optimized for torque.
But no kerosene-powered airframe will be able to compete with them, once they show up. Hydrogen turbines might outdo the fuel cell/motor combo, though.
Does it really help you if the engine weighs nothing when the batteries weigh a ton? Economically viable (battery powered) electric aircraft is sci-fi.
Yeah, but motor size might compete with other things in the limited space. If you get (say) 30L more space from making 4 motors smaller, then that's 30L you can use for batteries which is (....really bad napkin math...) perhaps around 10kWh?
Or 30L more trunk space or cabin space.
In a hypercar it's obviously even more cramped, but more importantly a smaller engine is lighter.
I'm really excited to see what smaller and more powerful motors combined with increasingly dense battery technology does for robotics. Anyone with knowledge or expertise care to predict the next 10 years?
I don't think we're close to the limits yet of how many kilowatts we can pack into a defined weight/volume.
For example, one could imagine a motor having many 'onion layers' from outside to inside, where half of the layers are stationary, and half move. Magnetic fields between the layers cause the torque. By making many smaller layers, magnetic flux paths are shorter, and therefore less metal is needed for a given pulling force, and hence less space.
Current motors have just two layers (rotor and stator), but in future motors with 10+ layers, total power in a given space will be very high - the only limit really will be cost and difficulty of manufacture, especially of complex bearing sets required to keep all the layers concentric.
Eventually, motors will become small and light enough that they get integrated into wheels, and suddenly car design will be dramatically simplified.
I need this for my Miata. I’ve been thinking that the area where the fuel tank is and behind the seats could hold batteries. The range with gas is like 200mi anyway so if I could get 100 out of electric With this performance I would go for it
If they made an electric vw bug I feel like we could make an electric Miata. It would be heavier yes but if we keep the weight close to the ground and centered it wouldn’t be that bad
So if anyone has looked into motors for electric bicycles, will probably have learnt, how the copper is wound is also important to the performance & characteristics of the motor as this link explains.
https://www.youtube.com/watch?v=rFSTg8BNhoQ
I dont think we are even scraping the surface when it comes to electrical motor efficiency, but I think we could be seeing some innovation creeping into things like the washing machine and electric lawnmower in the future.
We may still have many things we can do to improve the efficiency, but the efficiency pretty close to 100% already, with Tesla hitting around 94% in their motors. So not a lot of room there. But of course there is still room to shrink the motors, make the motors lighter, make the motors have more power that can be sustained over a broader range of speeds, etc.
But the motors are already not super heavy or big by automotive standards, so the net benefit of those improvements are not so great, at least in normal sized cars. The biggest thing I would like improved is the range of speeds at which peak power can be sustained. In my model 3, I have around 500hp at low speeds, but it starts tapering off after 40mph or so. The model S plaid reduces this tapering by using more motors, which allows different gearing so the optimum motor speed is hit at a higher vehicle speed, and a bit more voltage.
The thing about improving up from 94% is, we may not magically double the power savings. But say, going from 94% to 97% may cut the waste heat in half, which means you can suddenly run the same size motor with twice the current without melting it down. So there are some nice benefits possible there.
Look at things like the "microstepper drivers" and "inverter heat pumps" too; its not just that we're getting more motor options, we're getting better at switching and shaping rich, chunky amps with little cheap chips of glass. That's opening up all sorts of capabilities that were fairy tale expensive before if they were possible at all.
Hear hear! I think we're just beginning to understand how much we can use smart chips and intelligent switching to improve performance. All you need to do is look at one of the old motors with brushes to realize how far we've come.
Yes, tapping that regenerative power will be a major step towards wheels directly geared to a clutchless motor which will then eliminate drive train losses. And I think alot of motors dont do regen in any major way yet.
The problem with regen is its too spiky and lithium ion charging doesnt like that unlike lead acid which can handle it, but using multiple battery options is becoming more normal. Cars fitted with stop start technology typically have an additional battery using either the newer cheaper Enhanced Cyclic Mat (ECM) batteries and the more older more expensive Absorbent Glass Mat (AGM) batteries, but they work.
" dont think we are even scraping the surface when it comes to electrical motor efficiency"
It's not uncommon for electric motors to be well over 90% efficient, and approach 95% or better within their ideal RPM range.
Windings are just part of the design; there's the lamination of the rotor and its materials, and the arrangement of the magnets (for example, halbach arrays.)
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[ 3.0 ms ] story [ 306 ms ] threadEdit:"After 20 seconds, the figures drop to 134 hp and 184 lb-ft of torque.". That's more like it.
Almost exactly the same :)
Not at all unsolvable, you just want to consider it before you break your axles!
The same sorts of governing functions are computer managed in an ICE powered vehicle too.
On the other hand, a smaller, more powerful motor would probably need a lot of cooling. The Hyper9 is air cooled, and is supposedly about 96% efficient when it's in its optimal range. Sometimes it's nice to have things be simple. (The motor controller generally does need water cooling. It's not technically mandatory, but highly recommended.)
This is true of a lot of conversions: they aren't "destroying" a perfectly good ICE engine, they're salvaging a car that would otherwise be sent to the wrecker because it doesn't work anymore.
I think the RX-8 is a great platform for conversion because it's a nice, reasonably modern car and they can be had for almost nothing if the engine needs rebuilding, or is too damaged to be rebuilt.
Also, climate change is a thing. I'd expect more people are aware of that these days, and its hard to justify running such an inefficient engine even if they are admittedly really cool.
https://www.youtube.com/watch?v=8_ACg1JTqtY
Batteries, inverters etc are expensive.
Comparing a gas tank to EV batteries, the cost swings the other way unfortunately.
A smart company will come around one day with a targeted selection of cars for a "plug and play" wiring harnesses and control units.
I think that amount of power, although for only 20s, would make for a fun Tesla-beating hybrid sleeper.
tl;dw: It's much more involved than simply swapping the motor. You need to create a custom mounting bracket for the electric motor, you need batteries (used long-range 75 KwH Tesla batteries go for about $10k), you need a charging system, an electronic management system, and you need to find a way to power peripherals like A/C which are typically powered via a serpentine belt from an ICE.
https://electrek.co/2021/11/03/ford-is-selling-mach-e-crate-...
https://www.thedrive.com/news/43030/fords-already-out-of-390...
https://performanceparts.ford.com/part/M-9000-MACHE
> Mind you the work shops will bank even more with all the "scrap metal (engine block, catalytic converters etc)" so maybe we'd see free swap deals.
What? You severely over-estimate the value of that unprocessed "scrap metal."
Also, the EV motor is probably one of the least expensive parts of the system. It's the battery and inverter that are expensive.
whether material or production costs dominate is an interesting question.
EV motors often have absurdly high RPM limits, which may require some exotic materials and/or lubricants. (I think Tesla motors go up to about 18,000 rpm if memory serves.)
Copper for the windings is another high-cost material; copper has been expensive lately. You could use aluminum instead, but it would mean having to scale up the design or run at a lower power to compensate for the wire resistance.
I do hope to see good, cheap, powerful motors be a thing that was more available to random third parties to swap into their old ICE vehicles. Right now the best options seem to be to use something like a Netgain Hyper9, or scavange a drive unit out of something like a Leaf or Bolt or Tesla.
Optimizing things that aren't a bottleneck is almost never a good use of resources.
If this smaller motor is also cheaper because it uses less material that would be a win, but I suspect that's probably not the case. They also don't mention efficiency in the article, and that can be more important than size/weight.
I wonder how much Tesla pays for their motors. I wonder how much they'd save if they only needed 1/3rd as much material.
This kind of material-minimizing innovation seems like it could go a long way. It feels like if someone wanted to mass produce power-dense electric motors, they could radically reduce the cost of a motor by simply using less materials. If they can get to scale. If they can sell them like crazy, which they should, since they should be cheaper to make, as the material inputs are so much less.
Koenigsegg of course doesn't care about production costs. It's expected that every item that goes into the car is going to be built via the most exorbinant processes possible. But the underlying idea of using far less material to make a motor sounds extremely attractive to me.
The more efficient your motor is, the more mileage you get out of your battery, so the smaller your battery can be. It could easily be that an extra 1 kg of steel and copper shaves off 10 kg of lithium ion batteries.
Means you need very heavy duty wiring/controllers, high current rated batteries, can't use OEM power steering / AC compressors, can't use OEM battery packs, can't use DCFC infrastructure....
And why not? Power steering systems don't run on the HV system but on the LV system as every electric car has a DC/DC converter that bridges the HV and LV domains. So regardless if your cars is using 800V or 100V powertrain system, all the auxiliary equipment will still be on the 12V network.
I have wondered whether the Hyper9 can actually run at a higher voltage without damage. I suppose the limiting factors are the insulation on the motor windings and the ability to dissipate heat. (The motor demagnetizes if it gets too hot, which is why the motor has a temperature sensor so the controller can back off before that happens.) The Hyper9 comes with a motor controller that's limited to 180 volts (that's for the 144v nominal version). I don't know if anyone's tried to run a Hyper9 with a different controller that can handle much higher voltage, like 300 or 400v.
Officially specced for 25A, commonly run from 4S LiPo = 14V, but the current can go higher with good cooling or in bursts.
https://www.hyperflight.co.uk/products.asp?code=MEGA-16-15-4...
https://www.amazon.com/Flipsky-Hardened-Skateboard-Brushless...
(The idea that an e-skateboard can have four of those motors blows my mind. Suicide!)
It's not enough for a car. I don't want to get pedantic about it, sure it could power a clown car or two scooters and an umbrella duct taped together.
https://www.auto-data.net/en/citroen-ami-electric-5.5-kwh-8h...
5.5 kW to get 45 kmh speed (and 70 km range)
The UK site for it envisions a possible use for the "cargo" version for "last mile deliveries": https://www.citroen.co.uk/models/future-models/ami.html
https://www.youtube.com/watch?v=HcoVYZ20PwM
That said I think rocket lab gets 50hp out of the soup can sized motor they use for their turbo pumps.
So in this case let's take the position of the bend, where power goes flat (4000rpm, 250kW, 600Nm): P=4000 x 2x pi/60 1/s x 600 Nm = 251kW
Seems to be correct.
Not really. First, this number only applies to imperial units. Second, axis scaling will move the crossing point. The only way this happens (provided we are talking about imperial units) is if the torque and power axis scales are explicitly scales such that the curves intersect at 5252 RPM.
But - out of curiosity - why is the soda can measured in ml and not in fl oz?
I was always tought that the liter was an SI unit, I mean, it's defined in terms of SI units, I know it's not a base unit, but weird that it's singled out as "well, you're technically SI compatible, and you're defined in SI units, but we're not gonna let you be part of the group" :)
It even has an official SI symbol (L), despite not being an SI unit, what?!
So satisfying...
I'm all for metric or SI. But let's not overstate the value please.
It is the mixture of both that ends up being very confusing.
The advantage is not having to remember all those funny constants and being able to do math in your head that actually makes sense?
Or more important, to be able to write an article that the entire planet can just read without 95% of them (everybody outside the US, UK and Myanmar) having to resort to Google to find out if those numbers are impressive or not?
Just laugh at the joke.
For the last years I’ve mostly seen watts being used in NL, but it’s been ages since I saw a fast and furious movie or a top gear show. The car sellers use kW and often also, I assume metric, horsepower.
This, very much! I've done a ton of physical simulation code in my life. Whenever some newb or student comes to me for the first time with their simulation code that mysteriously doesn't work, in 90% of cases they stupidly didn't stick to SI and forked up some unit conversion, or mutiple. I tell the to keep it in SI and never let me see them make that mistake again. (Only exception is simple 1-to-1 unit conversions of parameters and results, when some stupid interface definition demands it that can't easily be changed.)
1. Everything uses a common base, so you don't get a base change on a scale change (or indeed, two different bases for different parts of the same measurement), and dimensional consistency becomes trivial.
2. The base is base-10, which is the same as our common counting system.
1. Temperature. It’s useful to elongate units over the range normally experienced by humans, which Fahrenheit does and Celsius does not, because it avoids tenths of a degree, for example, in room temperature selection.
2. Woodworking and similar: it’s useful to use powers of two because it’s very common to be marking/cutting/etc. 1/2 or 2x a value, which is easier to do in inverse power of two English measurements.
F*ck :D
Wish we could all start understanding the difference between kilo and kibi, mega and mebu and so on for bits and bytes.
https://en.wikipedia.org/wiki/Binary_prefix
After many years and different widths the smallest common unit of exchange evolved to be a power of two: 8 bits are a byte, not 9, 10, 27, 30, etc; though Unicode might have been better off if 32 bits were the base character. However then older systems would have been at least 75% less useful.
Physical addressing units are also binary, because literal address lines (or their virtually latched equivalents on a serial bit-shift register) are used.
ROM, RAM, and correspondingly non-volatile writable storage inherit this basic premise.
So a non-sales computer person speaking 'kilo' or 'mega' or any other SI unit in relation to a computer part means it will hold or be able to transfer at least that many SI units in the quoted units. Everything gets rounded to the nearest useful neighbor. A digital kilo is not 1000, it is 2^10. A digital mega is correspondingly also 2^20. This is very similar to the exponents in SI units.
For that matter, humans have 8 fingers and 2 thumbs. Wouldn't an octal numbering system make more sense? Though for that we'd have to come up with new unit names near 2^3, 2^6, 2^9, etc that don't sound silly.
Each of the 4 long fingers has 3 phalanges, so an interesting possibility is to use each thumb to count up to 12 on each hand. Given that many ancient units of measurement where base-12, I wonder why we didn't develop base-12 languages.
>Two common definitions used today are the mechanical horsepower (or imperial horsepower), which is about 745.7 watts and the metric horsepower, which is approximately 735.5 watts.
I guess speaking as a Brit the foreigners just didn't have proper horses.
Outside of these weird exceptions, it's SI all the way. And this doesn't really vary with age. The web site whrere you buy wheels and TVs doesn't know your age so it will say the rims or screens are 20" regardless of who you are.
This is all as it should, however a large number of people have a really hard time groking the difference between kW and kWh.
So much so that I wonder if we should start specifying battery capacity in MJ to help people clarify things in their heads.
Beaufort is a dimensionless label as far as I'm aware and grit is used as such too (i.e. it never says anything else than "240" i.e. it doesn't "240 grit" or "240 something per inch").
My list wasn't close to exhaustive. We use all kinds of weird units.
Besides bar I sometimes see mmHg for pressure. Shoe sizes. I've never seen acceleration in m/s2 outside a physics problem, otherwise it's either G or seconds to 100 km/hr.
I'm aware. But I'd say its mostly used as a dimensionless. When I argue "we use metric except for these few" I mean in the cases where the unit (a length, mass, pressure etc) is actually uttered or written.
In some cases as you note there are labels which have non-metric definitions underneath, such as sand paper particles having a never-pronounced inch definition. The same goes for some weapon calibers where you might say a ".303 cartrige" for rifle ammunition but you'd never say a ".303 inch cartidge". A lot of people probably use these labels without knowing they are using an imperial definition. And that (I'm guessing) is also part of why it survived the metrification.
> I've never seen acceleration in m/s2 outside a physics problem, otherwise it's either G or seconds to 100 km/hr.
"10s to 100km/h" is as metric as m/s2 though (But again not pure SI). g being a constant obviously has no explicit unit, it's as metric as you want it to be :) I hear "5g" as 5x9.82m/s2 but an american probably hears something else.
It's even more pronounced with camera sensors, the size given in fractions of an inch is some kind of "equivalent to", whereas the size in mm is the actual size. Apparently the image sensor inch is 16mm or something like that.
As a European I find Fahrenheit kind of makes sense on a human scale as 0 and 100 are the upper and lower limits of it being reasonable to be outside. Below 0 is "too cold", above 100 is "too warm" and when it is 50 it is neither warm or cold.
https://en.wikipedia.org/wiki/Metric_Conversion_Act
https://en.wikipedia.org/wiki/Metre_Convention
> The Metre Convention (French: Convention du Mètre), also known as the Treaty of the Metre,[1] is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Sweden and Norway, Switzerland, Ottoman Empire, United States of America, and Venezuela).
A passenger jet can attempt a landing on a 3000 feet long runway from 4 nautical miles from touchdown point, flying 250 knots at 1500 feet. Altimeters must be calibrated to announced local atmospheric pressure, or the default to 29.92 inHg or 1013 hPa.
Autoclave is a device used for sterilization that exploits saturated(pressure equal to ambient) steam. It is usually ran for 15 minutes at 121C(250F). According to a random internet source[1], atmospheric pressure at sea level is around 15 psi, and 250F is the point where pressure of steam exceeds that, being a function of temperature.
(One of) the beauty of SI units is measurement devices itself are universally built and marked in SI units that disparate measurements across industries can be converted and compared against. There is no “3000 feet runway 4 miles away” in metric, it’s a 1km runway 6.5km away. There is no need to convert between inHg and feet and PSI, or lb-ft and inch-pounds just because F.G. Superman in 1337 who pioneered art of bicycle repairing set measurement and tolerance for a bike frame to be 50 +/- 3.5 inch-yard per fortnight centigrade.
But that requires phenomena to be well studied and measurements clearly defined against SI units, which is a point more industries than we care to admit has reached.
That has to be an aspect of why imperial units persist, despite NASA and cutting edge aerospace are moving away from it, other than there would be a simple matter of gross widespread ignorance.
1: https://biology.stackexchange.com/questions/95722/why-do-we-...
It has since been redefined based on that original definition, as 1852 meters.
So it’s a goofy measure in that it uses base-60, but is otherwise more in the SI family both in terms of original derivation from natural measurements and in terms of its current SI-based definition.
https://en.m.wikipedia.org/wiki/Nautical_mile
There are other things out there called a “mile” that aren’t imperial, too. Take care when asking for directions in the Norwegian countryside, for example: https://en.m.wikipedia.org/wiki/Scandinavian_mile
Like, yes, because you haven't established whether they mean US MPG or Imperial MPG.
This is one of the illustration with online or even real world discussions where we argue pass each other under the wrong basic assumption.
In the German speaking world everyone knows what a hp is (PS), how much his car has, his past cars had, in which configurations their car is available... although the kW is what is printed on the documents since ages now.
Nobody likes change. Some people still complain about the Euro, and that the DM was so much better... At least it is not called ECU.
"The country where everything is bigger (*)"
(* except for consumer goods that would be designed around a practicable supply current of 10A elsewhere)
But seriously, I do like the split-phase power we have in the US. I think we get the best of both worlds, having lower voltages in most living spaces, and higher voltages reserved for high-power appliances.
How is this possibly a benefit for anything though. It's not like 110V is safer in any practical way, if you stick something in a socket it will kill you just as much as 220V would, so it seems like for literally no reason at all American homes have a much less "ability" to support a wide range of devices that work without any issue elsewhere in the world.
I've been shocked with 120v on bare skin multiple times.
Current code in US/Canada also requires RCDs (we call them GFCI) in some places (and AFCI everywhere, which the rest of the world hasn't really adopted) and shuttered outlets... but these do not catch all types of faults. For instance, if a human conducts electricity across two conductors connected to an RCD/GFCI, it won't trip. It only trips if current is drawn to ground or to another circuit. Layered safety is a good approach.
That's not to say that 240v systems are unsafe -- they just have different characteristics and requirements because of it.
1. https://en.wikipedia.org/wiki/Metric_prefix
Expressing quantities in SI units doesn't require 'base units'. SI prefixes are permitted (milli, micro, kilo, mega...), as are certain exclusions (including minutes, hours, ...).
That said, I think the US car industry has moved to metric and it is great to not need multiple sets of everything.
If we have 2mm of rain in Copenhagen this afternoon, and my yard measures 8m×12m, how much water must drain away?
How much rain falls on the whole city?> my yard measures 8m
You use a very long unit of measure.
What about if it isn't water you are calculating but some other substance? You use a look up table to find the factors - we need to look up a but more in the table, but it isn't a big deal.
I always hear that argument about "but when will I need it?" If you're using this system then you're always going to use it. It comes up all the time, it's natural so you don't think about it too much.
Does it mean it's better? Well yes, but it doesn't mean other measuring systems aren't good. You don't need it, but you'll want it once you learn it.
The second is obviously relevant for the people responsible for rivers, storm drains, sewers, dams, hydropower and so on. When we start terraforming Venus, we'll need to add the conversion factor for sulphuric acid rain.
Sure I can do the math to calculate it in my head and take a few seconds.
How many meters are in 240cm? Don't need to 'calculate' it the same method. I just move the decimal over. 2.4m...
I say this as an American who finds our use of Imperial pointless. Infact, there is a highway in Arizona that uses metric instead of imperial, as it was a part of our move to metric. (The current measuring and weights system in the United States is based on Metric, we do use it, just converted into another measure)
Every time I need to add or subtract two measurements.
Quick:
What is 2' 3 5/8" plus or minus 1' 2 19/32"?
or
What is 701.7 mm plus or minus 370.7 mm?
Seriously I work with both everyday, and while I grew up with inches & feet and I still intuitively know how deep two feet of snow is better than 61 cm of snow, I'm really starting to hate the US measurements, and use metric whenever I can.
Also, whenever we deal with things from the rest of the world, it becomes a mashup of US and metric measurements.
The US almost converted to metric in the 1970s, but Nixon squashed it, basically on the complaints of what are surely the ancestors of modern US right wing know-nothings who didn't like "foreign" stuff.
Looking at it historically, the fractions made a lot of sense when things were more coarse, and the ability to split things into even sections, 1/2, 1/3, 1/4... was more common.
OTOH, Metric was designed for doing calculations - we already use the decimal system for all other math, so we should design a measuring system to use the same calculation system. It really does work better.
A few brake lines and some old exhaust bits might be SAE, but by and large vehicles are done with metric.
Personally I like that SAE has fewer sizes... Its frustrating as hell working on cars with a mixmatch of 6mm 7mm and 8mm bolts. oh this is a 15 but a few awkward 16s! Mostly though, cars are pretty standard. European cars seem to be basically - 7mm 8mm (hose clamps and other tiny stuff) 10mm (air filter housings and such where 8mm is to small) 12mm 13mm (misc bolts, intake manifolds, exhaust, almost everything) 15mm 17mm 19mm (these larger ones are basically suspension and other large components)
This one is definitely changing. Lots of people here only know their weight in kg now (including me).
Is that with younger generations? Most people I know doesn't have clue about their weight in Kg.
It's not that great a motor design. It's good, but we had similar power to weight motors where I worked 10 years ago and could run 200kW for more than 20 seconds. Good motor designs are cool, but IMHO they are usually not news-worthy but are just marketing.
The article is written for an American magazine while the pictures are from Koenigsegg directly, which are European; beverages use ml and l to measure contents.
Take a look at the graph, also provided by Koenigsegg, it uses Nm and kW.
complete shitshow.
Where in Europe are you that anyone uses kW for engine power lol. Yes it's listed in kW on my registration document but I've literally never heard anyone using kilowatts to describe engine power instead of horsepower, and I lived in a few European countries so far.
The problem with switching the US to the metric system is that the cost would be truly massive. It would take decades, somewhere in the order of 50 years, for a complete conversion.
There's the obvious, things like every single highway sign would have to be replaced. And then there's everything else, like every single tool that everyone owns in this country would have to be replaced at some point. You would still have to be able to buy and use imperial unit hardware and tools for decades during and likely after the transition. I can't possibly list just how deep and wide such a conversion would have to reach.
And that's assuming everyone goes along for the ride. That said, a 50 year timeline would mean a new generation would grow up using the metric system. Another 25 years after that and we should be OK.
All of that said, the real problem is political. The cost of such a transition would be significant. Politicians will only get behind things they can convert into votes. Going metric isn't one of these things. Spending billions of dollars over five decades isn't something anyone can use to win an election. Most people aren't close enough to the design and manufacturing of goods to understand just how much this system actually hurts us. And so, going metric, in a practical sense, becomes an impossible dream.
This said as a French and ex-physicist.
For example 160kw, 6.7kw/kg motor https://www.yasa.com/products/yasa-p400/
[1] https://www.backfireboards.com/products/backfire-g3-with-sup...
[2] https://news.ycombinator.com/item?id=29797315
Sure, for slow vehicles where these things don't matter, hub motors work great, but not for your typical road going car. They could put one of these near each wheel and drive the wheels via axles.
Pro: get rid of the differential.
Cons: have less power overall, less efficiency (for an electric motor?), more losses. Probably.
Intuitively, I always figured that having mass on an object that’s very low to the ground is a good thing, but I can imagine it’s something different when it’s attached to a wheel.
[1] https://www.lazareth.fr/project/e-wazuma/
They probably don't make sense on cars though as explained by other people here.
[0] https://arstechnica.com/cars/2020/02/check-out-the-first-eve...
Oh, here we go:
> In 1900, at the Paris Exposition Universelle…[0]
[0] https://www.automobiliardent.com/index.php/home/article_deta...
Some turbocharged combustion engines also have something called overboost, allowing short periods of operation at higher power than the "continuous" limit (again due to heat build-up)
The TLDR is production cars are "fused" at the factory to only work with firmware signed for production vehicles and devs can't produce these production builds themselves. There is facilities for live patching production cars but these systems are even more restrictive.
On the other hand... all bets are off in an engineering car. :P
I'm sure they can still overheat based on other limitations (coolant radiator, pipe size etc...) but these can be rights sized based on trim level.
Slightly different if you expect to be able to take it around a track.
Stall torque = current, and there is no trick around that.
Also, aren't energy drink cans larger than coke cans? I haven't had a can in front of me for years, so using cm (or inches) would have been better.
The 250 ml comes in a 14 cm height box, so I guess the 13 cm were a correct guess?
A 330 ml "Sleek Can", which I guess is the same one as a Red Bull can, has a height of 146 mm.
It's just as valid as using bananas for scale, but the issue with the article is that that it doesn't even bother to mention the actual dimensions in cm or inches, yet it uses "tiny" in the title to describe the engine.
It just means it's a standard european small-but-tall style can. There are 2shapes of 330ml cans, the shorter/stubbier one and the taller narrower one which was initially most common in energy drinks but is now used for soda cans too. Beer still uses the shorter/stubbier 330ml.
I believe they are around 14.5 cm high. Diameter around 6cm.
Here's the same press release written in metric land:
https://www.autodaily.com.au/koenigsegg-designs-in-house-ev-...
It's good that people are getting the weight down of these motors, but i'm still unsure why I need 250kW+, let alone two of them built into the drivetrain.
I've managed with <100kW for the last 30 years in my cars of choice, and I know headline figures sell stuff, but we're trying to save the planet at the moment. But I guess if it convinces petrolheads that there's still fun to be had going electric that serves a purpose...
So it's certainly true that most of us here probably aren't the target for Koenigsegg super cars, we might be indirectly consumers of the engines or engine technologies they create.
Koenigsegg has been an incredible company to follow and their CEO is such a pleasure to listen to that they're one of the few auto companies that I'm excited about. I'd be even more excited if they took a path similar to Tesla or Polestar and started offering an affordable brand of EVs.
Although it’s worth noting that “trickle down” tech advancements are quite a powerful force in the automotive industry
An oversized battery, or oversized wiring, will generally be more efficient due to reduced resistive losses. Larger components (such as are designed to handle high power levels) have lower electrical resistance.
(Resistive heating power) = (current)^2 * (resistance)
- "smaller" cables in CPU make for lower energy consumption
- "larger" cables in engine reduce resistance
With electric motors, it's completely different - the amount of physical work that comes out of the motor is fixed - you can't reduce it like you can with information processing. So, you're purely looking at improving the efficiency of the conversion from electric power to mechanical power. A larger motor allows you to do that with thicker wires (so less resistance to heat up) and with things moving at a slower speed inside (which also helps). The only downside of a larger motor is if you have to carry it with you - that could reduce your efficiency by making the vehicle heavier. However, electric motors are generally remarkably efficient these days, and the main consequence of the inefficiency is heat generation, which gives us the other advantage of making it bigger - it is easier to dissipate heat from a larger object than a smaller object.
1. (useful energy out) / (energy in)
2. (theoretical minimum energy consumption) / (actual energy consumption)
In thermodynamic systems the second is often expressed as "isentropic efficiency" or similar.
In computing the second term can also be expressed using Landauer's limit [0], the theoretical minimum energy consumption of computation. Current computers are still shockingly inefficient in this regard, taking several orders of magnitude more energy usage than the "ideal" minimum.
So really, as inefficient as a gasoline engine is, it's nowhere near as bad as even the smallest, most modern CPU.
"Millions of times" level of inefficiency is like burning banknotes for warmth.
https://en.m.wikipedia.org/wiki/Landauer%27s_principle
So, given a beefy fuel cell and liquified hydrogen tank (bonus points for aerogel insulation), an electric motor optimized for energy efficiency is likely to be more useful than one optimized for torque.
But no kerosene-powered airframe will be able to compete with them, once they show up. Hydrogen turbines might outdo the fuel cell/motor combo, though.
In a hypercar it's obviously even more cramped, but more importantly a smaller engine is lighter.
https://www.youtube.com/watch?v=1mPmCDS66Qc
For example, one could imagine a motor having many 'onion layers' from outside to inside, where half of the layers are stationary, and half move. Magnetic fields between the layers cause the torque. By making many smaller layers, magnetic flux paths are shorter, and therefore less metal is needed for a given pulling force, and hence less space.
Current motors have just two layers (rotor and stator), but in future motors with 10+ layers, total power in a given space will be very high - the only limit really will be cost and difficulty of manufacture, especially of complex bearing sets required to keep all the layers concentric.
Eventually, motors will become small and light enough that they get integrated into wheels, and suddenly car design will be dramatically simplified.
But there are also many many other things which can be tweaked on an electric motor to alter characteristics as this blog explains. https://www.electricbicycleworld.com/blog/review-of-ebike-mo...
I dont think we are even scraping the surface when it comes to electrical motor efficiency, but I think we could be seeing some innovation creeping into things like the washing machine and electric lawnmower in the future.
But the motors are already not super heavy or big by automotive standards, so the net benefit of those improvements are not so great, at least in normal sized cars. The biggest thing I would like improved is the range of speeds at which peak power can be sustained. In my model 3, I have around 500hp at low speeds, but it starts tapering off after 40mph or so. The model S plaid reduces this tapering by using more motors, which allows different gearing so the optimum motor speed is hit at a higher vehicle speed, and a bit more voltage.
The problem with regen is its too spiky and lithium ion charging doesnt like that unlike lead acid which can handle it, but using multiple battery options is becoming more normal. Cars fitted with stop start technology typically have an additional battery using either the newer cheaper Enhanced Cyclic Mat (ECM) batteries and the more older more expensive Absorbent Glass Mat (AGM) batteries, but they work.
It's not uncommon for electric motors to be well over 90% efficient, and approach 95% or better within their ideal RPM range.
Windings are just part of the design; there's the lamination of the rotor and its materials, and the arrangement of the magnets (for example, halbach arrays.)