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on Gopher (inofficial)
HTML Visit Hacker News on the Web
COMMENT PAGE FOR:
HTML Electric motors with no rare earths
Danox wrote 7 hours 21 min ago:
Really sounds promising. The question is will the French have the will
to build it in bulk on shore in France or Europe? Thereâs no point if
they want to sub it out to the world to build cheaper somewhere else?
This technology does show that you should never give up on industry,
research, development and building on shore.
latentframe wrote 7 hours 40 min ago:
One of the most interesting thing about commodity bottlenecks is that
they often accelerate substitution ; scarcity can end up by making a
material being less important
ZedZark wrote 8 hours 25 min ago:
Say all you want about the inferior efficiency and so on, but if
nothing else they have proven that it's viable, even commercially. So
the rare earths are really not as vital as they have been made out to
be.
kopirgan wrote 10 hours 44 min ago:
Broader point is this: Middle East created oil crisis back in 70s.
Since then US economy has grown enormously while it's still using
pretty much same amount of oil, imported or otherwise. They shot
themselves in their foot. Iran is doing this now, telling the world to
avoid Hormuz. They will learn to do that.
China is doing that by blackmailing countries with rare earth.
Answers will be found. Especially as some of finest brains across 2
continents + Japan are very interested in doing it. In the past, China
could flood market at right time to make alternatives unviable. But
that trick has worn off.
In this context, 92% or even 80% efficiency of permanent magnets is no
big deal. It'll not be the answer to every use case but will satisfy
many and limit demand.
coryrc wrote 5 hours 18 min ago:
I don't know. Europe had the opportunity to make themselves energy
independent multiple times; instead they doubled down on Russian oil,
and in response to the latest invasion, they instead doubled down on
Qatar natural gas...
Germany spent enough on solar to have nuclear power for winter
heating and instead they get nearly nothing from it when energy (note
I said Energy not Electricity) demand is the highest: winter heating.
Now, if they had put that solar in North Africa and ran cables, sure,
but they didn't. Or if they did Drake's landing solar storage, that
would also work. But they spent a fortune only to still be completely
dependent on fossil fuels and are destroying the economic base
because of the cost.
jfengel wrote 9 hours 24 min ago:
In the long term solutions will be found, but in the short term they
can gain an enormous bargaining chip. If food prices double because
we've burnt the last drop from the Strategic Petroleum Reserve, the
administration will give them just about anything they want to avoid
utter political destruction.
The game theoretic definition of a threat is something that harms
you, but harms them so much that they will avoid forcing you to
trigger the threat. It's a different matrix from the Prisoner's
Dilemma, but still leaves you guessing about the personality of your
opponent. The personality of Iran seems reasonably consistent. The
US, less so.
RobotToaster wrote 14 hours 38 min ago:
Why not just use an induction motor with VFD?
adrian_b wrote 13 hours 13 min ago:
As said in the parent Web page, lower energy efficiency, thus shorter
range with the same battery.
Another poster has mentioned that BMW also uses EESMs instead of
permanent-motor magnets.
BMW uses EESMs as the main motors, on the rear axle, while they use
induction motors as auxiliary motors on the front axle.
Besides being cheaper, the induction motors have the advantage that
if they are used only as auxiliary motors, you can cut the power
supply to them at any time, in which case they will consume nothing.
So their lower efficiency does not matter, because most of the time
they are turned off.
CarVac wrote 10 hours 45 min ago:
> Besides being cheaper, the induction motors have the advantage
that if they are used only as auxiliary motors, you can cut the
power supply to them at any time, in which case they will consume
nothing.
EESMs have this advantage too, you can simply cut power to the
field winding.
adrian_b wrote 15 hours 4 min ago:
Unfortunately, their Web page does not say a single word about the
important problems of their motors.
The electrically excited synchronous motors have been known forever,
but they had not been used in EVs because of 2 disadvantages.
The first is that traditional EESMs require brushes, i.e. sliding
electrical contacts, which are worn out by friction, so such motors
require frequent maintenance for changing the brushes.
It is possible to make brushless EESMs, but they require a rotating
transformer and a semiconductor rectifier inside the rotor.
The second disadvantage is a lower efficiency than with permanent
magnets, which cannot be improved so much as to match PM motors,
because the electrical currents that circulate through the rotor
windings must generate heat. The lower efficiency also makes cooling
more difficult.
Renault says that their EESMs have an efficiency of 92%. This is a good
efficiency, even if not as good as attainable with permanent magnets.
Losing a few percents in efficiency is an acceptable compromise for
avoiding the use of expensive and supply-constrained chemical elements.
What I wonder is whether Renault reaches this 92% efficiency with EESMs
having brushes, or with brushless EESMs, and this is what I would have
liked to read on the parent Web page.
Brushless EESMs usually had a lower efficiency, so 92% would be
impressive for them, while it would look normal for EESMs with brushes.
If Renault has succeeded to make a brushless EESM (i.e.
maintenance-free) with an efficiency of 92%, that is something worth to
brag about. Otherwise, making a traditional EESM would not be great
news, because everybody has avoided those because of the maintenance
problem.
ErroneousBosh wrote 4 hours 0 min ago:
> electrically excited synchronous motors
So hold on, their amazing technological innovation is...
a washing machine motor?
petre wrote 5 hours 52 min ago:
> The second disadvantage is a lower efficiency than with permanent
magnets, which cannot be improved so much as to match PM motors,
because the electrical currents that circulate through the rotor
windings must generate heat. The lower efficiency also makes cooling
more difficult.
It depends.
With PM motors if you exceed the Curie temperature, the magnets lose
their magnetism. Also one can control the rotor excitation current on
EESMs so core saturation is less of an issue compared to PMSMs.
The brushes are also quite long lasting and easy to change on a good
design so maintenance is not as a big of an issue.
ASMs are even more robust but they have lower power density and
efficiency but are better for coasting.
There is also the SynRM which uses an unwound rotor with flux
barriers (cutouts) that aligns with the stator flux, no magnets
needed. It's basically as robust as the ASM but without its lower
efficiency disadvantages and also no brushes, at the cost of more
complex power electronics and lower speed noise.
MisterTea wrote 7 hours 38 min ago:
> so such motors require frequent maintenance for changing the
brushes.
Define frequent. I maintain machinery with brushes so I have a decent
idea of what life span should be depending on the environment. If the
housing for the slip ring setup is well protected from dirt and the
slip rings aren't cleaned by a cave man you can get a few years of
life from the brushes.
chipsa wrote 7 hours 30 min ago:
If the desired location for this is a car, then a few years of life
that requires half disassembly of a motor isnât going to work.
coryrc wrote 5 hours 27 min ago:
The slip rings are not in the middle of the motor, they're on the
butt. I know car makers don't always try to make things
serviceable, but it'll be hard to make it hard to replace.
Probably the only issue will be needing to remove other parts
first to get to it, if anything.
w4der wrote 6 hours 24 min ago:
That does not sound worse than replacing the spark plugs in a
Subaru engine.
RicoElectrico wrote 9 hours 18 min ago:
> The second disadvantage is a lower efficiency than with permanent
magnets, which cannot be improved so much as to match PM motors,
because the electrical currents that circulate through the rotor
windings must generate heat. The lower efficiency also makes cooling
more difficult.
Wouldn't the back EMF help here? In brushed DC motor it surely does,
reducing losses way below what full voltage over winding resistance
would incur.
cbolton wrote 7 hours 51 min ago:
That just means lower net voltage => lower current => lower torque
right? When you do need torque you need current and the losses that
come with it.
torginus wrote 10 hours 10 min ago:
Munro took apart a Nissan Ariya which has this exact kind of motor.
The maintenance is basically removing a tiny cover and replacing the
tiny and cheap carbon brushes every 100k km or more. It's basically
cabin filter level maintenance.
And they said that PMSM motors are more efficient at low RPM, but
their coils get saturated at higher RPMs meaning they lose efficiency
at highway speeds (which actually affect the range number people car
about).
So overall not such a bad tradeoff, if it makes cars less expensive.
runeks wrote 5 hours 14 min ago:
> [...] but their coils get saturated at higher RPMs meaning they
lose efficiency at highway speeds (which actually affect the range
number people car about).
This seems like a big disadvantage. Highway is exactly where EVs
fare worst compared to ICE cars.
I wonder if this could be solved by introducing a gearbox?
I know the new Mercedes CLA (EV) has two gears, the second gear
being optimized for highway speeds. But I don't know whether it's
related to this.
antalis wrote 2 hours 2 min ago:
To be clear: a big disadvantage of permanent magnet motors
(PMSM).
HTML [1]: https://youtu.be/BFmp9ODkCA8?t=725
teamonkey wrote 2 hours 27 min ago:
It canât be that bad because the latest Renault EVs have pretty
good real world range figures in their class.
CarVac wrote 10 hours 46 min ago:
Efficiency varies according to the load and RPM.
Permanent magnet motors have higher peak efficiency but EESMs are
better in non ideal conditions, particularly low torque high RPM i.e.
highway cruising where efficiency is more critical than at low
speeds.
psd1 wrote 11 hours 14 min ago:
TFA does specifically call out the lower efficiency of eesm. I guess
it was edited after you wrote your comment.
Efficiency schmischiency. I see your 3% and raise you the abolition
of SUVs.
I see your motor-brush maintenance burden with my washer fluid,
tyres, brakes, seals bearings bulbs filters etc etc. Then I raise you
control modules that send your car to three garages and the
scrapyard. Cars have wear items, you heard it here first.
adev_ wrote 12 hours 40 min ago:
> such motors require frequent maintenance for changing the brushes.
"Frequent" is all relative.
The Renault Zoe, 10y ago, was already using a synchronous engine with
wired rotor. And most were going over 150kkm without any issues nor
brush changes.
> because the electrical currents that circulate through the rotor
windings must generate heat
Currently stator heat in wired synchronous engine is less a problem
than in SynRMs with permanent magnets.
Most neodymium based permanent magnets start to be irreversibly
damaged id they heat up beyond 100°C. That's currently why Tesla has
such a good cooling system in their engine.
Wired rotor are bunch of copper coil, as such they are much more
resistant to temperature gradients.
wolfi1 wrote 5 hours 58 min ago:
150kkm - wouldn't that be 150 Mm?
ben_w wrote 5 hours 11 min ago:
Sure, also 1 mAU and 0.5 light seconds, but treating km as a base
unit and prefixing it with another k isn't too uncommon a
misuse.
halper wrote 5 hours 11 min ago:
Yes, you are correct. As the SI brochure states: "Compound prefix
symbols, i.e. prefix symbols formed by the juxtaposition of two
or more
prefix symbols, are not permitted."
Unfortunately, almost no one uses SI units and/or prefixes
correctly.
duffydotsvg wrote 12 hours 50 min ago:
Amazing breakdown for someone (me) who knows literally nothing about
how motors work.
bornfreddy wrote 14 hours 36 min ago:
Interesting question, it looks like they are / will be brushelss:
> Group will gradually embed new technological improvements from 2024
on its EESM: stator hairpin, glued motor stack, *brushless* and
hollow rotor shafts.
[0] [1] That said, what sibling says about the maintenance problems
is very true. :-/
HTML [1]: https://www.evspecifications.com/en/news/6ec9484
Karliss wrote 12 hours 20 min ago:
All sources point that their 2025 models are still using brushed
rotors. Here is a teardown video it's from Nisan car but it's using
a Renault electric motor [1] .
In the picture at Renault website (section describing their next
gen 2027 motors) you can clearly see the 2 slip rings on right
side. That might be just a placeholder using their last gen motor,
but I would expect that they would mention it if their next gen was
brushless while the current one has brushes.
Brushless seems to be a thing that they have described as future
work for at least 5 years but it's not there yet.
HTML [1]: https://www.youtube.com/watch?v=BFmp9ODkCA8
ece wrote 10 hours 17 min ago:
Compared to an ICE, maintenance of brushes is still quite an
improvement.
whazor wrote 14 hours 52 min ago:
Not sure how familiar you are with Renault, but âmaintenance
problemsâ pretty much sums up a lot of older Renaults.
prmoustache wrote 6 hours 33 min ago:
There were models with tons of problems, other that were bullet
proof really.
I think if we take french cars (Renault/Peugeot/Citroen) in
general, most major reliability issues have been on diesel cars
exhaust gas recirculation systems due to strict european emissions
and they are far from the only brands suffering from that.
German cars were known for their great reliability in the early
90's but in later decades had all sort of electronical gremlins.
Also I think regardless of their actual current reliability, some
brands or models attract on average different kind of owners which
impact how actual services are followed, if the car is stored
inside or outside, if the owner take care or not of warming up the
engine in the morning or floor it while cold, and the general care
they apply to it.
sofixa wrote 13 hours 6 min ago:
Which "older" ones? The original 5 is kind of a tank.
gattilorenz wrote 11 hours 48 min ago:
I didn't know tank have regular problems with starting,
especially in cold weather, regardless of whether the choke is
open or not :)
BoredPositron wrote 11 hours 36 min ago:
Yeah, if we are talking about cars with choke we can say with
confidence that most of the original engineering team is in
retirement.
mirsadm wrote 13 hours 6 min ago:
What does older mean in this context? Because some people still
think the year 1996 wasn't that long ago. Modern Renault cars are
fine and reliable enough. I've had 4 in my life time and had zero
issues myself. I see a ton of them here in the UK and, again,
they're fine.
ReptileMan wrote 13 hours 18 min ago:
As the old saying goes - better a naughty French than boring
German...
dcanelhas wrote 15 hours 56 min ago:
Clearly making a motor with induced magnetic fields both for the stator
and rotor isn't the innovation here, since a large fraction of
industrial motors do not have permanent magnets.
I would assume the innovation here would need to be making it small and
efficient for any meaningful torque output? Usually when you see claims
of a 93% efficient electrical motor its the result of taking an
absolute beast of a 2kW machine and operating it at 400W. Does anyone
have insights into what Renault are doing here?
rbanffy wrote 13 hours 51 min ago:
The real innovation is in making them brushless and essentially
maintenance free while still being efficient enough.
general_error wrote 16 hours 45 min ago:
I own a Zoe for that reason
bestouff wrote 15 hours 18 min ago:
I also have a Zoé (an R135). Wonderful little machine.
PowerElectronix wrote 16 hours 47 min ago:
Rare earth magnets are just too good for electric motors to go this
way. Europe and the US just need to get the rare earth manufacturing
going and stop being reliant on china for this stuff.
E-Reverance wrote 17 hours 31 min ago:
"At the same time, China is also the world's leading producer of
electric cars..."
Kind of interesting for a professionally branded company to use "..."
like that
numpad0 wrote 21 hours 36 min ago:
Weren't Tesla ACIM drive unit motors before Model 3 also magnet-free? I
thought they used passive isolated bundles of copper wires and their
reluctance as magnets.
MrDrMcCoy wrote 22 hours 8 min ago:
It's a bummer they are not really available in the US.
alephnerd wrote 22 hours 3 min ago:
EVs in the US and China tend to use PMSMs, though GM, Stellantis, the
DoE, and the DoD are funding an EESM startup [0]
[0] -
HTML [1]: https://nironmagnetics.com/
ipbrown wrote 8 hours 21 min ago:
Niron is not developing an EESM. They are developing Iron Nitride
permanent magnets. These magnets can be used in a variable flux
permanent magnet synchronous machine (VFPMSM). Variable flux
machines have some similar characteristics to EESMs in terms of
their ability to change the field excitation, but they are
fundamentally different than EESM in terms of how they do so. EESM
change their field excitation and VFPMSMs change the magnetization
state through stator current pulses. Their current/torque
regulation control is also quite different.
There are other startup companies developing EESMs but not Niron to
my knowledge.
isopede wrote 23 hours 22 min ago:
Does regenerative braking work with a motor like this?
cwillu wrote 22 hours 57 min ago:
Yes: IIRC some large generators work exactly like this, as the
energized rotor gives a lot more flexibility in managing frequency
and power output.
fc417fc802 wrote 21 hours 7 min ago:
Not just some, approximately all of them. It greatly complicates
the logistics of a black start. â Of course that situation has
additional complexity due to the need for substantial additional
power in order for the various fuel supply systems to operate but I
digress.
â
HTML [1]: https://en.wikipedia.org/wiki/Black_start
tlb wrote 14 hours 51 min ago:
Generator excitation is not the hard part of a black start. You
have to run coal feeders, blowers, and water pumps for an hour
before you can spin the generator. Then you get power instantly
upon applying power to the field windings.
cesarb wrote 7 hours 51 min ago:
> You have to run coal feeders, blowers, and water pumps for an
hour before you can spin the generator.
That's probably the reason most grid black start facilities in
my country (Brazil) are hydroelectric dams, which need none of
these.
msandford wrote 12 hours 6 min ago:
And even that's not the hard part of a black start. The plant
control is relatively easy. What's hard is grid coordination.
All generation and consumption have to be almost perfectly
balanced every second of every day. And the power company
doesn't have good addressability of load. Worse when you
restore power to an area all their stuff turns on in parallel
giving an inrush that could be 3x or more the steady state.
A black start is a very drawn out process of bringing
generation and load online in a balanced way and with wait
times between load increases for stabilization.
ahartmetz wrote 23 hours 6 min ago:
After watching a Munro video about it, I see your point. In the motor
shown, the rotor gets its magnetic field simply by inducing a current
and a field in it in reaction to the stator's field. There are no
electromagnets in the rotor like I expected. In that case, I'm not
sure either... I'd say more likely than not but it's complicated
since the stator basically needs to induce a field and at the same
time recover energy from the field that comes back from the rotor. I
would further guess that the phase shift between the two components
makes it possible to treat them separately.
Previous comment: Don't see why not - the "field" coils (the ones
that replace the permanent magnets) need to be energized, which can
initially come from the batteries if necessary.
maxerickson wrote 21 hours 12 min ago:
There are electromagnets in the rotor, it is directly energized.
userbinator wrote 23 hours 27 min ago:
A historical pioneer in the complex technology of electric motors
without magnets
Those who know the history of electric machines will find the title and
verbiage very amusing. Motors with no permanent magnets were the first
practical ones, and at this point wound-rotor motors are over a century
old.
It's worth noting that some of the biggest motors have always been
designed this way, because the size of magnets required would make them
both too expensive and dangerous, and still not powerful enough for
their size; a field coil can generate a field that's only limited by
the current and resistive heating of the winding, but rare earth
magnets have fixed limits on field strength.
anonymousiam wrote 18 hours 27 min ago:
You're right about the verbiage being amusing.
All big generators have an exciter coil that is used to generate the
magnetic field. It has the advantage of allowing voltage regulation
through adjustment of the field, rather than after the fact, which
would be far less efficient.
In both motors and generators, there is an efficiency hit related to
the need to supply power in order to generate the field, but when you
scale up the system, it actually becomes more efficient to use the
electromagnet. With the rare-earth mineral shortage, it makes even
more sense.
rdtsc wrote 8 hours 39 min ago:
> field. It has the advantage of allowing voltage regulation
through adjustment of the field, rather than after the fact, which
would be far less efficient
That and not having huge strong magnets is nice when doing
maintenance.
WalterBright wrote 19 hours 18 min ago:
Long ago, when I was in Cub Scouts, one of the projects was to build
an electric motor. The parts list was:
1. a plank to form the base
2. several 6 inch nails
3. wire
4. a tin can (as a source of sheet metal)
5. tape
No magnets. But it worked perfectly fine when connected to a dry
cell. Adventurous science lad that I was, I decided it would work
better when connected to AC. So I attached a power cord and plugged
it in.
A loud vibration ensued, and then it burst into flames. My mom wasn't
happy.
toss1 wrote 11 hours 10 min ago:
One of my favorite sayings:
"Good judgement comes from experience; experience comes from bad
judgement."
I commend your excellent use of bad judgement there, WalterBright
(despite your mom's lack of enthusiasm)!
actinium226 wrote 12 hours 49 min ago:
Username checks out.
rbanffy wrote 13 hours 57 min ago:
That 60Hz sound is a sure sign we did something very wrong. By the
time you hear it itâs usually too late to say âUh ohâ
Daub wrote 19 hours 2 min ago:
Been there. Im gonna guess that 90% of HN folk have similar stories
to tell.
WalterBright wrote 17 hours 39 min ago:
The Cub Scouts in the 1960s were a lot of fun. Each den meeting
involved a project. The other one I remember was we each built a
kite from scratch.
Mine was a bit fragile, and the first gust of wind shredded the
sticks and plastic film.
But it was still fun!
As a teen I built a flame thrower. No, I'm not going to explain
how to build one. My dad told me that God looks out for little
boys, because otherwise they'd never survive to adulthood.
When I was 9, I found a book of his "Rocket Manual for Amateurs".
The opening sentence was something like "if you're fascinated by
things that burn and explode, this book is not for you." Who
could resist a teaser like that? I promptly read it cover to
cover. He wouldn't let me buy any of the necessary materials.
Daub wrote 10 hours 41 min ago:
> if you're fascinated by things that burn and explode, this
book is not for you.
Translation⦠âread me now!â
ridgeguy wrote 15 hours 47 min ago:
"Rocket Manual for Amateurs" was my favorite book after I found
it in 8th grade. In high school I had a chem teacher who would
give me chemicals so I could experiment with what I'd read. A
great book for budding Raketenkinder.
WalterBright wrote 19 hours 11 min ago:
P.S. I still use tin cans as a source of sheet metal. There was a
big storm a while ago, with tree branches whistling by at high
speed. (Not a good time to be outside.)
Three holes were punched in the house by the branches, 1-2 inches
in diameter. What to do, what to do. I took a coke can, slit it and
unrolled it into sheet metal. Then cut a disk bigger than the hole,
and epoxied it into place. Worked like a charm, and cost nothing.
I've used coke can metal for shingles and flashing, too. They don't
rust.
psd1 wrote 11 hours 8 min ago:
I like that story. I fixed a microwave door latch with a beer-can
shim and some decorative ribbon; we used it another 11 years.
fragmede wrote 18 hours 54 min ago:
there's also a plastic liner on them that I'm sure helps.
echoangle wrote 18 hours 52 min ago:
It also helps that they are made from aluminum which doesnât
rust like iron does.
hdrz wrote 15 hours 40 min ago:
It rusts just like iron, but the rust (AlOx, or alumina)
stays bonded to the metal and actually protects it.
wongarsu wrote 14 hours 19 min ago:
In other words: it rusts, but it doesn't rust like iron. It
rusts in a much less destructive way because the aluminum
oxide protects the rest of the aluminum from oxygen
redeeman wrote 9 hours 51 min ago:
it does not rust, it corrodes :)
lloeki wrote 14 hours 23 min ago:
Rust being literal Fe2O3 makes a convincing argument that
aluminium sure oxidises but doesn't rust pretty much by
definition ;)
euroderf wrote 16 hours 5 min ago:
And epoxy binds to aluminum just fine ? Epoxy is weird. What
solid material does it NOT bond to ?
mjanx123 wrote 15 hours 49 min ago:
It does not bond to polypropylene and other low surface
energy plastics
psd1 wrote 11 hours 10 min ago:
Terminology question - I understood those to be
"high-energy" surfaces, because the chains are strongly
bound. Is it a typo, or am I wrong?
AlotOfReading wrote 15 hours 51 min ago:
Polyethylene, like they use in food containers. Virtually
nothing sticks to it unless specifically designed.
ridgeguy wrote 15 hours 52 min ago:
Teflon.
cen0b wrote 15 hours 2 min ago:
Yummy, my favorite!
echoangle wrote 13 hours 7 min ago:
Actually should be mostly fine since itâs pretty
inert, unless you eat the stuff used to make it.
xeonmc wrote 21 hours 50 min ago:
What advantage do permanent magnets provide that it isn't the case
that all motors are made without them?
sitharus wrote 21 hours 30 min ago:
A lack of wear components.
A permanent magnet motor uses permanent magnets on the rotor, but
an electrically excited synchronous motor has an electromagnet on
the rotor. This requires a rotating electrical contact which has
normally been made with slip rings and carbon brushes. These wear
over time and need replacement.
Most large electric generators are externally excited synchronous
generators using carbon slip rings, so it's a well understood
field.
This can be made contactless using inductive coupling and a
rectifier - since inductive coupling needs AC but the excitation
coil needs DC - at the expense of some efficiency.
You can see the efficiency difference - Renault claim 92%
efficiency but permanent magnet motor EVs have touted efficiency
over 95% in the motor.
ipbrown wrote 8 hours 31 min ago:
I am a little surprised that Renault is only claiming a drive
cycle efficiency of 92% (unclear for which drive cycle). It is
possible to design EESM with brushless high frequency rotating
transformers and rectifiers for WLPT drive cycles with greater
than 94% almost 95% efficiency.
snovv_crash wrote 17 hours 50 min ago:
You can also make squirrel-cage rotors that are auto-inductive in
the sense that they resist slip from the rotating field of the
stator. This is also extremely simple to manufacture and doesn't
require driving separate fields or anything similar.
adrian_b wrote 14 hours 38 min ago:
This is mentioned in the parent page, where it is also
mentioned that their disadvantage is a lower energy efficiency
than either electrically-excited synchronous motors or
permanent-magnet motors.
The lower efficiency means a lower range for the same battery,
which is why the companies that have used them in the past,
like Tesla, have abandoned them.
Permanent-magnet motors have the highest possible energy
efficiency, followed by electrically-excited synchronous
motors, than by the induction motors mentioned by you.
Both permanent-magnet motors and induction motors do not
contain parts that need frequent maintenance, while this
property is more difficult to achieve for electrically-excited
synchronous motors.
hulitu wrote 13 hours 38 min ago:
> The lower efficiency means a lower range for the same
battery,
And some heat which must be dissipated or else they will
dethrone the BMW as the leading burning car. /s
Rapzid wrote 21 hours 20 min ago:
To a layman that seems like a really small efficiency tax if you
can't get your hands on the magnets for some reason.
tbrownaw wrote 19 hours 46 min ago:
You can get about 2/3 as much output power for a given amount
of waste heat and cooling capacity.
It's like how laptop power bricks used to be big and get hot,
and now they aren't and don't.
_kulang wrote 20 hours 43 min ago:
Itâs a near-doubling of energy loss - probably a healthier
way to understand it when the efficiencies are all 90%+
Maxion wrote 18 hours 53 min ago:
Funnily enough if enough of that energy loss (heat) can be
scavange, this wouldn't be nearly that bad for us living up
here in the cold.
antonkochubey wrote 14 hours 38 min ago:
In most EVs motors are watercooled, so that energy can
indeed be scavenged â problem is, during low-speed
driving, the heat output is not high enough to get
noticeably above ambient temperature.
handstitched wrote 21 hours 7 min ago:
It's a small difference, but if you had a choice between "more
efficient AND less maintenance" and "less efficient and more
maintenance" then it's easy to see why the permanent-magnet
solution is preferred.
mcdonje wrote 12 hours 10 min ago:
Another comment said they're not using brushes, so they
shouldn't need more maintenance.
namibj wrote 20 hours 39 min ago:
The actual alternative is induction motors, which are just a
bit less efficient than PMSM and otherwise basically the
same. Except that the frequency fed to them isn't exactly
proportional to speed.
They've been used to great success since we had the needed
power electronics to drive the electric trains of Europe.
XorNot wrote 22 hours 57 min ago:
Not quite true: you're also limited by the mechanical strength of
your windings and core (this is the upper limit on superconducting
magnets like at CERN and in fusion plants).
Jblx2 wrote 22 hours 54 min ago:
And if you also ignore iron saturation.
ipbrown wrote 23 hours 32 min ago:
Electrically excited synchronous machines (EESMs), also known as wound
field synchronous machines (WFSMs) have a number of potential
advantages and disadvantages compared to interior permanent magnet
synchronous machines (IPMSMs). IPMSMs are the dominant motor topology
currently in use for North American electric vehicles.
Advantages:
- Not subject to the price and supply chain volatility of rare earth
permanent magnets.
- For highway dominant drive cycles, the cycle efficiency of EESMs can
be higher than state of the art IPMSMs. EESMs tend to have their best
efficiency at moderate torques and high speeds because of their
excellent field weakening characteristics. I tend to think that they
would be a good fit for application in class 8 trucks or as auxiliary
motors in automobiles with two powered axles.
- The output torque doesn't necessarily decrease with rotor
temperature. In IPMSMs the permanent magnet flux linkage decreases with
rotor temperature.
- At least theoretically, with proper control, it is possible to
operate EESMs with unity power factor and decrease the kVA rating of
the stator inverter.
- If there is a stator inverter fault, there are schemes to denergize
the rotor which have some safety implications.
Disadvantages:
- DC current needs to be transferred to the rotating field winding. For
automotive applications this tends to be done either with brushes and
slip rings or brushlessly using a high frequency transformer with a
rotating rectifier. In either case additional power electronics and
other components are needed for the field power transfer and control
which reduces some of the potential cost savings of the elimination of
the permanent magnets. If brushes and slip rings are used with oil
spray/oil jet cooling of the rotor they need to be sealed in a separate
compartment. I am a little surprised that Renault has stuck with
brushes and slip rings versus an inductive high frequency transformer
solution. I think this has limited their power density.
- For very torque dense machines, cooling the rotor field winding is
challenging, and in my opinion is best accomplished by oil spray/oil
jet cooling.
- It is difficult to reach the same maximum speeds as IPMSMs in an
automotive package size. The rotor field winding retention system to
keep the field turns from moving into the airgap at high speeds needs
considerable attention during the design.
- The overall axial length of the non-active region of EESMs is
typically longer than IPMSMs because of the field winding end turns and
field excitation system.
- EESM efficiency is dominated by the manufacturable slot fill of the
field winding.
- High performance current/torque regulation is considerably more
difficult.
High performance EESMs have been used in aerospace generator
applications for decades, albeit with a different rotor excitation
system than what is used in automotive applications. Renault (and their
supplier Continental) really led the commercialization of EESMs into
automotive mass production. Now BMW has followed suit and multiple
suppliers have EESM designs (Mahle, ZF, etc.) GM had a really nice EESM
design and high frequency transformer excitation which they published
back in 2014. My colleagues and I built several generations of EESMs as
part of U.S. Dept. of Energy projects ( [1] ) and I think they have
their place as EV traction motors for certain applications.
HTML [1]: https://www.osti.gov/servlets/purl/1837809
schobi wrote 15 hours 39 min ago:
I see another advantage..
You can switch a motor without permanent magnets to "idle mode".
I understand in Tesla dual motor configurations, the front motor is
without magnets. The excitation field will be turned on when you need
extra power, but at crusing speed it does not cause extra "drag".
From one teardown I've seen, they even went so far to use cheaper and
less efficient IGBTs for the front drive, and more efficient SiC
Mosfets for the rear motor (in the same vehicle!). If you need extra
acceleration briefly, lower efficiency can be accepted.
gmac wrote 16 hours 14 min ago:
Itâs interesting that EESMs can be more efficient at high/highway
speeds, and itâs something I had read before. This seems to me to
be a key advantage of EESMs, because when people worry about EV
range, they worry mainly about range on long-distance, high-speed
journeys.
(I have a Renault EV and itâs excellent. Aside from the motor
technology, itâs relatively light, has a heat pump as standard, and
a good-sized battery).
ipbrown wrote 8 hours 19 min ago:
EESMs generally are not great at city driving cycles compared to
IPMSMs. They do really excel in field weakening at moderate
torques.
giobox wrote 23 hours 36 min ago:
It's interesting that this is a brushed design. In the RC car
community, brushless motors are generally regarded as superior, but
those of course have the rare earth magnet problem.
Technically the brushes can wear out, although there are claims they
are good for 150,000-250,000 miles it seems.
Devorlon wrote 12 hours 48 min ago:
It's brushless:
HTML [1]: https://www.evspecifications.com/images/news/6ec9484/additio...
amelius wrote 10 hours 36 min ago:
Makes me wonder why they made that choice, if what your parent
commenter said is true.
dreamcompiler wrote 20 hours 35 min ago:
"Brushless DC motors" are good because brushed DC motors are
constantly switching polarity, which causes arcing of the brushes,
which causes wear. The brushes are not there to energize the rotor;
the rotor is just magnets after all. The brushes are there to tell
the stator to change polarity.
Brushless DC motors don't arc -- because they switch stator polarity
with electronics that sense the position of the rotor without rubbing
parts. (They can also fine-tune the stator current spikes to make the
motor very efficient over a wide speed range, which brushed DC motors
cannot do.) The lack of arcing is more important than the fact that
they don't have rotating contact points.
Brushed AC motors have rotating contact points (slip rings) but they
don't arc (ideally), so the contact points don't degrade as fast as
brushed DC motors do. But they do carry a lot of current because
their purpose is to energize the rotor. Brushed AC motors are not
ideal, but making an AC motor "brushless" is not nearly as big a win
as making a DC motor brushless.
Wait. You're saying DC motors require current that's constantly
switching polarity? So they're sort of really AC internally?
Yep. All motors require constantly changing current. The distinction
between AC and DC motors is whether you feed the motor externally
with current that is already alternating sinusoidally, or whether the
motor itself turns external DC into some kind of AC.
hnav wrote 23 hours 32 min ago:
It's technically not a brush but a slip-ring. The design of these
motors is very similar to automotive alternators, just scaled up 100x
(in terms of power).
adrian_b wrote 13 hours 21 min ago:
Brushes are used everywhere for transmitting electrical current
between two parts that have an unlimited relative motion.
Brushes are typically made of graphite mixed with some binder. The
graphite conducts the electrical current, but it also acts as a
lubricant.
The metallic part that is in contact with the brush is called a
slip ring, if it is continuous, like in synchronous motors, or a
collector ring if it is segmented, like in DC motors or
single-phase motors with brushes.
genter wrote 23 hours 19 min ago:
I've probably taken apart 10 automotive alternators. Every single
one had brushes.
hnav wrote 22 hours 58 min ago:
yeah I misspoke, I meant to say that it's a brush riding on a
slip-ring (continuous contact, no arcing, lasts long) rather than
a bunch of contacts in a cylinder (commutator, arcing, wears
out).
dheera wrote 23 hours 29 min ago:
Slip rings have brushes.
raverbashing wrote 23 hours 13 min ago:
Yes but they wear less than DC brushed motors exactly because
it's a slip ring and not a commutator
ahartmetz wrote 23 hours 9 min ago:
Because it's the discontinuities in the commutator where the
sparks fly (with much help from self-induction of the motor's
coils) and erode the ring and brushes.
hijinks wrote 23 hours 51 min ago:
let me guess.. but its 2x the price?
hnav wrote 23 hours 42 min ago:
no, but requires introduces brushes (slip-rings really) which is a
wear item
jillesvangurp wrote 18 hours 7 min ago:
I don't think car owners have to worry about this the first half
million miles or so with these motors. Electrical motors last a
long time. We'll know for sure in a few decades, I guess. That's
how long it will take for a significant number of their cars to
actually drive that far.
Also, compare this to ICE engines which experience continuous
explosions, lots of mechanical parts, extreme temperature swings,
etc. and still manage pretty decent durability. There's simply no
base for assuming that parts like this wearing out and needing to
be replaced is going to be a common thing.
theodric wrote 17 hours 26 min ago:
The Continental and Renault motors like those in my Kangoo ZE and
Zoe have so far proven fairly reliable, with the occasional
exception being shaft bearings. The Q210 is particularly robust.
I'm not aware of anybody having brush/slip ring issues yet.
themafia wrote 23 hours 16 min ago:
Cars already have lots of wear items and a mature service industry
for them. If I can reliably get at least 50k miles out of it,
then I wouldn't be all that bothered, as this is not likely to be
an expensive part or service.
hnav wrote 22 hours 35 min ago:
so apparently on the BMW i4s it requires a rear subframe drop
which isn't going to be cheap (10s of hours).
drnick1 wrote 22 hours 49 min ago:
> mature service industry for them
The car service industry is a scam, and I am glad that EVs
require minimal to no servicing that cannot be easily DIY like
tires and brakes.
stavros wrote 14 hours 58 min ago:
Yet they still charge me the same price as my ICE to service!
What a scam.
derac wrote 1 day ago:
[1] This is a helpful explanation of what this technology is and looks
like. (Munro)
HTML [1]: https://youtu.be/FHufjrP0xDI?is=xmFQrXGa1dBHM67I
lowbloodsugar wrote 23 hours 45 min ago:
It was a dude with motors on a table with a flip board. No
animations. No diagrams. When it got to the point about having one of
each motor, and using the best, he then said that you use the
permanent motor even when the other makes sense. Ok, well then why
have the two different kinds of motors? No answer. Just handwaved. If
you can't use the induction motor when its most efficient, because
thats when the permanent motor is causing spin loss, why have the
induction motor at all? No answer.
So. Analog presentation. Actual motors on a desk with a flip chart.
No animations. No internal visualizations. One page had diagrams that
would have been better super-imposed (or hey, animated). Then one
page the begs questions with no answers given.
willXare wrote 1 day ago:
"Replace the magnet with a controllable magnet" is probably the most
automotive-engineering sentence possible.
pfannl wrote 1 day ago:
Also known as: âwe removed the rare earths and added software.â
dreamcompiler wrote 20 hours 10 min ago:
Rare earth magnet motors require software too if you want them to
be maximally efficient. You could embody that software in e.g. an
FPGA of course, but it's still software.
Jblx2 wrote 1 day ago:
Synchronous motors: running on software since the 1880s. Nikola
really was ahead of his time!
hnav wrote 23 hours 33 min ago:
He invented the induction motor which runs right off the grid.
adrian_b wrote 13 hours 47 min ago:
Tesla had invented a kind of two-phase induction motor, but the
three-phase induction motor that is the ancestor of the modern
induction motors was invented in 1891 by Mikhail
Dolivo-Dobrovolsky (working in Germany at AEG), who had also
invented in 1888 the three-phase grid, the three-phase
generator and the three-phase synchronous motor.
The Dolivo-Dobrovolsky motor is the ancestor of all high-power
induction motors, while the Tesla motor can be considered the
ancestor of the single-phase induction motors that have been
used (more frequently in the past than today) for several
household appliances, like washing machines (or reel-to-reel
magnetic tape recorders, a half of century ago).
regularfry wrote 16 hours 23 min ago:
Other way round. He invented the induction motor (1887) which
the three-phase grid was then demonstrated to drive (1891).
That's how influential it was. There are other reasons a
three-phase grid is handy but being able to drive these
brushless contraptions must have seemed utterly wild at the
time.
adrian_b wrote 13 hours 37 min ago:
A three-phase grid cannot drive a two-phase induction motor,
like that invented by Tesla.
In 1891, the three-phase induction motor was invented by
Mikhail Dolivo-Dobrovolsky, combining the principles of the
three-phase synchronous motor previously invented by Mikhail
Dolivo-Dobrovolsky with the principle of the induction motors
invented by Nikola Tesla and Galileo Ferraris.
Like any inventions, the induction motors of Nikola Tesla and
Galileo Ferraris had not sprung out of nothing, but they were
based on the experimental observation that had been known for
many decades that if you rotate some magnets around a disk of
copper, the disk will rotate, even if the magnets do not have
any action on the disk when stationary.
Because of the symmetry, it is easier to generate
electromechanically three-phase currents than two-phase
currents where the phase difference must be precisely of one
right angle.
delfugal wrote 1 day ago:
How soon to see rare-earth-free paired with CATL Sodium batteries?
Seems a price war, range war is imminent.
cogman10 wrote 1 day ago:
Could be wrong, but AFAIK the CATL Sodium batteries haven't yet hit
LFP pricing.
You are unlikely to see a vehicle with sodium batteries until after
that happens, and it needs to be significantly less than LFPs as you
Na batteries have more weight per Wh. I believe they also have a
shorter lifespan (but not NMC short). Edit correction, looks like
CATL is promising 15000 cycles, which is much longer than LFPs which
usually come in at 7000 to 10000.
It seems far more likely to me that if the Na prices tank, you'll
probably first see them deployed as grid and home battery solutions.
adrian_b wrote 13 hours 8 min ago:
For about a half of year there have been cars with sodium-ion
batteries, in China. As you say, for now they are more expensive,
but it is expected that the price will drop quickly in the
following years.
Because they lose neither capacity nor charging speed at low
temperatures, like the lithium-ion batteries, they expect that in
the future sodium-batteries will be the best choice in the
countries with cold climates.
gpm wrote 23 hours 57 min ago:
They're promising to start selling a Qiyuan A06 variant with Sodium
batteries sometime this year... so if you went looking you could
probably see one... or will be able to soon.
Manuel_D wrote 1 day ago:
The energy density of LFP batteries are also 30-50% higher than
sodium based battery chemistries. Even if sodium battery prices
drop, the lower energy density is a big disadvantage. My
understanding is that sodium batteries are aimed at stationary
use-cases, like battery buffers for fast charging.
jillesvangurp wrote 18 hours 14 min ago:
At the cell level yes. But at the pack level, you need less/no
cooling and there is virtually no risk of runaway fires. This
means the cells can be packed more densely and you get some
weight benefits for all the stuff you no longer need for fire
safety.
CATL already put sodium ion in cheap cars. And there are other
benefits to this type of battery like a wider range of operating
temperatures that cover essentially all of the extreme
temperatures you'd find in the arctic and the hottest deserts.
I would not be surprised to find some of these batteries in big
semis a few years down the line when the cost benefits make the
space/weight sacrifices worth the trade off.
But you are right that domestic and grid storage are also going
to be huge use cases.
AtlasBarfed wrote 1 day ago:
Superior temperature range in cold weather as well IIRC.
nine_k wrote 1 day ago:
Looks ideal for a power wall at home.
MaKey wrote 1 day ago:
One of the most interesting features of sodium batteries is that
they still perform good in cold temperatures.
cromka wrote 1 day ago:
And high temperatures, too. Meaning they don't require cooling
nor heating, basically matching the per kg capacity of ready
modules with LFP while being significantly safer and less
complex.
alephnerd wrote 1 day ago:
Unlikely.
EESMs are primarily manufactured by European OEMs (ZF, MAHLE,
Schaffler, AEM) and their Indian JV partners (Sona Comstar, Sterling,
and the India branches of the OEMs listed). Both have been blocked
via export controls from accessing battery tech from China over the
past few years, and a major reason for the push for EESMs was for an
ex-China supply chain, especially after China began export
controlling rare earths to the EU [6].
Additonally, Chinese and American EVs tend to use PMSMs unlike
European and now Indian EVs. Also, the EU is cracking down on
automotive exports (cars and OEMs) from non-FTA states as part of the
EU Industrial Accelerator Act (which btw has made China go ballistic
[2][3][4][5]).
On the other hand, they will most likely use Japanese or Korean
solid-state batteries as Idemetsu Kosan is in the process of mass
producing them [0][1] as is LG [7], and both Japan+SK are FTA
partners with the EU.
[0] - [1] - [2] - [3] - [4] [4] - [5] [5] - [6] [6] - [7] [7] -
HTML [1]: https://www.chiyodacorp.com/en/projects/solidelectrolytefaci...
HTML [2]: https://battery-tech.net/battery-markets-news/idemitsu-kosan...
HTML [3]: https://www.globaltimes.cn/page/202605/1361926.shtml
HTML [4]: https://www.globaltimes.cn/page/202605/1362200.shtml
HTML [5]: https://www.globaltimes.cn/page/202605/1362161.shtml
HTML [6]: https://www.ft.com/content/5903318c-319b-426e-b05d-062f7620f...
HTML [7]: https://www.reuters.com/world/china/eu-lawmakers-rebuke-chin...
HTML [8]: https://blog.lgchem.com/en/2026/03/25_solid_state_battery/
alephnerd wrote 1 day ago:
Mentioned in another HN thread [0]:
They're also used by Nissan [1], BMW [2], and Indian EVs [3].
European firms like ZF, Valeo, MAHLE, and Schaffler along with British
firms like AEM have been working with their Indian JVs as well as
Indian players like Sona Comstar and Sterling for a couple years now to
integrate supply chains for mass-producing EESMs.
EESMs as well as the larger OEM story played a role in helping land the
EU-India and the UK-India FTAs because the supply chains for
French+Italian (Renault, Stellantis), Japanese (Toyota, Honda, Suzuki),
Korean (Hyundai-Kia), and Indian automotive manufacturers merged.
On the other hand, EESM EVs aren't a thing here in North America nor
China yet as both primarily use PMSMs (edited typo).
[0] - [1] - [2] - [3] - [4] ---
Edit: can't reply
> does Nissan still use these motors, the car in the linked article has
been discontinued
Yes. The Ariya was discontinued in North America (EDIT: USA, TIL still
sold in Canada) but is still manufactured and sold in Asia.
> European and Indian manufacturers/engineering are definitely not in
the same category though
It's the same manufacturers and supply chain now.
Renault and their OEMs are the biggest driver for EESM, and Renault's
largest markets and manufacturing hubs are France, India, and Romania.
Heck, Renault is now going to start exporting it's Made in India cars
and parts back to the EU [0] becuase of the EU-India FTA.
And the European OEMs have transferred the IP for EESMs to Indian JVs
as I mentioned. It's the same style of tech transfer as Samsung did for
BYD and TDK for CATL for battery chemistry in the 2000s. Heck, Valeo
[1], MAHLE [2], ZF [3], and Schaffler [4] are opening and expanding
factories and R&D hubs dedicated to EV transmission manufacturing in
India for domestic and export usecases.
Also, if you've ever driven a Japanese (Toyota, Honda, Suzuki) or
Korean (Hyundai, Kia) make care in the EU, Australia, Middle East,
Africa, or Asia outside of their home countries their parts sourcing
and even the entire manufactured car would have come from India, such
as the Toyota Urban Cruiser EV [5].
[0] - [5] [1] - [6] [2] - [7] [3] - [8] [4] - [9] [5] - [10]
HTML [1]: https://news.ycombinator.com/item?id=48510402
HTML [2]: https://leandesign.com/nissan-ariya-magnet-free-motor-teardown...
HTML [3]: https://www.bmwblog.com/2025/02/20/bmw-gen6-electric-motors-ne...
HTML [4]: https://www.reuters.com/world/china/india-revs-up-alternate-ev...
HTML [5]: https://m.economictimes.com/industry/auto/auto-news/india-eu-f...
HTML [6]: https://www.valeo.com/en/valeo-inaugurates-new-electric-powert...
HTML [7]: https://auto.economictimes.indiatimes.com/news/auto-technology...
HTML [8]: https://press.zf.com/press/en/releases/release_66050.html
HTML [9]: https://www.basispointinsight.com/Story/schaeffler-india-opens...
HTML [10]: https://newsroom.toyota.eu/the-all-new-toyota-urban-cruiser/
IlikeMadison wrote 21 hours 28 min ago:
No, and it was mentioned by the consortium of European cars
manufacturers after the joint press release with Der Leyen herself:
the implementation of factories and research centers in India is
solely to be able to sell on that market. It is the exact same
process that happened with China in the past. The exact same also
happened with Airbus.
You are also wrong on the market importance for Renault. For 2024,
France was the biggest, followed by Italy, Turkey, Spain, Germany,
Brazil, UK, Morocco, BENELUX, Romania, Poland, Netherlands and... #13
India with 0.9% market share...
Supply chains didn't change at all, in fact it did the opposite, and
Europeans won't rely on anything Indian made for the near future, as
local re-industrialization is already acted on and even accelerated
since the pandemic.
Production numbers across all manufacturers even Volkswagen (which
was unexpected) show the number of cars manufactured in Europe
increased in the past 2 years.
Electric cars in Europe mostly come from China, the US and European
brands. Nothing Indian-made, not even parts.
heresie-dabord wrote 23 hours 35 min ago:
> The Ariya was discontinued in North America but is still
manufactured and sold in Asia.
The Nissan Ariya is NOT discontinued in North America. Nissan no
longer sells it in the USA because of Trump's tariff war.
The Nissan Ariya is still sold in Canada.
IlikeMadison wrote 23 hours 54 min ago:
European and Indian manufacturers/engineering are definitely not in
the same category though.
AtlasBarfed wrote 1 day ago:
what is a prsm? Do you mean pmsm?
analogpixel wrote 1 day ago:
Not sure why this was voted down, it was the most useful comment
here.
does Nissan still use these motors, the car in the linked article has
been discontinued, and then only real info I can find on their site
about the leaf is about their ROCKIN' bose sound system/s
IlikeMadison wrote 21 hours 26 min ago:
Because it's grossly untrue and backed with propaganda slop
articles. I suspect this is a bot.
bgarbiak wrote 1 day ago:
BMW also makes rare-earths-free motors for their EVs and - at this very
moment - theirs are far more advanced. They offer almost twice the
power (up to 300kW vs 160kW) and are on a 800v architecture.
Quarrel wrote 22 hours 1 min ago:
Which is quite the contrast to Mercedes new axial flux electric
motor, which goes all in on rare earths- the design relies on the
highest end high-grade permanent magnets.
Still, presumably Mercedes ambitions are for few motors than BMW or
Renault.
andwur wrote 21 hours 18 min ago:
Vastly different target market and/or features there. Mercedes are
chasing maximum power density, minimum weight for high performance
deployments, with seemingly little concern for cost or supply
chain.
Renault is going after the consumer market with these motors, where
minimising cost and maximising availability is more important than
pushing past 95% efficiency or cramming a 700kW power output in a
motor that is small and light enough to fit inside of a wheel hub.
PedroBatista wrote 1 day ago:
The cheapest EV model Renault sells is around â¬20K, the cheapest
BMW EV is around â¬65K.
It's safe to say the companies are not in the market bracket, no?
tencentshill wrote 18 hours 45 min ago:
BMW also produces Mini EVs, which start at £26,840
bgarbiak wrote 17 hours 5 min ago:
The cheapest Minis are made by GWM in China, and are using
different motors and batteries.
However, comparing prices between cars nowadays is a complicated
matter. BMW's iX1 and iX2 (they use the BMW EESM motors)
theoretically cost about â¬55k, but they have been very recently
available to lease for about â¬250 euro per month - so pretty
much for the same price as the cheapest electric Renault if
leased.
fnord77 wrote 21 hours 37 min ago:
same order of magnitude :)
lostlogin wrote 23 hours 26 min ago:
The bit the gets me more than the sale price is servicing.
BMWs have a terrible record for needing expensive repairs.
I know you shouldnât rely on anecdote, but it seems I do.
throwaway2037 wrote 17 hours 30 min ago:
> BMWs have a terrible record for needing expensive repairs.
EVs? That makes no sense. EVs are so much simpler to maintain
compared to ICEs.
joe_mamba wrote 4 hours 46 min ago:
Simpler != more reliable. Electronics fail quite often too.
Just ask SSDs.
Also new EVs fail often too due to being cost cut to the
extreme with the "move fast and break things".
monster_truck wrote 13 hours 40 min ago:
They suffer from some of the same problem your likely modern
fridge does, and then kick it up two notches.
In the name of "safety", they have made design decisions such
as integrating fuses directly into the very large and expensive
control boards and making them non-replacable. Just in case
this wasn't enough, they also tend to blow an OTP so that in
the event that you have the know how to replace the fuses
anyways, nothing will work. Naturally you also cannot just swap
in a replacement board, as it needs to go through the same
pairing process to the ECU as things like the car doors, which
in most cases requires an active certificate/license on the ecu
programmer that only dealerships/oem have.
throwaway2037 wrote 26 min ago:
Wow, I stand corrected. Hat tip for the excellent reply.
Assuming what you wrote is true, then, yes, I agree.
conductr wrote 12 hours 17 min ago:
This is a company intentionally making sure EVs didnât
erode service revenues
IshKebab wrote 15 hours 59 min ago:
In theory they should be, but EVs also tend to be more
computerised, proprietary and locked down than ICE cars, so in
practice I think it's not as simple as that.
For example there was that case of the car that needed an
entire new sealed â¬5k battery controller because it was in a
minor crash and blew a fuse.
My garage charges 50% more for labour on EVs. I'm sure part of
that is price discrimination but I bet part is also because
working on them is more difficult. I would not be surprised if
they need to pay more for access to the manufacturer's
diagnostic tools too, which are becoming increasingly required.
seanmcdirmid wrote 19 hours 42 min ago:
The only way I would buy a BMW is if it were an EV. Iâm just
not brave (or rich) enough to buy their ICEs.
mjanx123 wrote 15 hours 42 min ago:
The BMW inline 6 were the best engines ever. Their inline 4 and
other are a strong contender for the worst engines ever.
psd1 wrote 10 hours 58 min ago:
I miss my E39 530 every time I drive. My next 90s Jag is also
going to be a straight-six; the V12 is glorious but heavy.
tylerflick wrote 12 hours 5 min ago:
I assume youâre talking about the n52 vs n20. Iâve had
both engines as daily drivers, and theyâre both fine. The
n20 has a bad rap due to early models failing from a timing
chain guides breaking.
irishcoffee wrote 19 hours 44 min ago:
If you take care of the car itâs just brake pads, tires,
rotors. Pads and rotors are really simple to DIY. Tires are more
expensive than like⦠an Elantra, but if youâre buying a 60k
car you can afford 1.2k in tires⦠otherwise donât buy the
car.
If you get into an accident or let the bmw get into disrepair via
neglect, yeah itâs not cheap to clean up. Body work is
expensive on any car though, and I donât have sympathy for
people who own higher-end cars and donât take care of them,
they deserve to pay the price for it.
ricardobeat wrote 11 hours 32 min ago:
Mostly just tires and minor maintenance. You're unlikely to
need pad and rotor replacements unless you're driving as if you
were on a racetrack every single day.
With daily EV driving you have the opposite problem - regen
means you rarely, if ever, actually activate the brakes, so you
get rust on them that you need to clean out.
scheme271 wrote 19 hours 33 min ago:
It's more than that though. Any repairs due to wear and tear or
whatever, ends up being really expensive. Although you can
probably reduce the costs a bit if you get the non-branded OEM
part or potentially the same part from another manufacturer
(e.g. the toyota supra uses a lot of bmw parts so if the toyota
part might be cheaper than the same bmw part).
irishcoffee wrote 19 hours 9 min ago:
That was my whole point actually, the wear and tear is really
minimal if you get regular oil changes. Things donât just
break and need replacing. Tires, rotors, brakes, those wear
out. The tires are not cheap, rotors and pads arenât crazy
expensive and super easy to DIY.
What other wear and tear things are expensive?
carefulfungi wrote 12 hours 12 min ago:
Owned a BMW. Had the audacity to use non-BMW windshield
washer fluid. The fluid sensor broke; because in a BMW
itâs a fancy sensor that is only compatible with specific
washing fluids. Sums up my experience with that car. It was
nice to sit in, though.
sroussey wrote 18 hours 42 min ago:
After 22 years, my z4 has needed batteries and a starter.
Recently, there was a problem with the engine misfiring but
it was $200.
LA, California
regularfry wrote 16 hours 31 min ago:
If you had bought a 7 or 5 Series at that time, you would
not have had that experience. The 2001 7 Series had
something like a 25% roadside breakdown rate.
dmurray wrote 14 hours 16 min ago:
25% every journey, or 25% over the lifetime of the car?
Neither seems really believable but I don't understand
how else you would measure this.
regularfry wrote 8 hours 18 min ago:
25% of cars. It was... not good.
dmurray wrote 7 hours 23 min ago:
So like... One in four cars would break down at the
side of the road before it was otherwise EOL? One
roadside breakdown every 800,000 miles or so? That
really doesn't sound bad.
irishcoffee wrote 2 hours 46 min ago:
It wasnât/isnât. The reactions in this
subthread surprised me. I guess itâs an
anti-ICE thing?
nine_k wrote 1 day ago:
It's still good to know that SOTA is further, and we can expect the
more advanced designs to seep into more affordable segments.
alephnerd wrote 1 day ago:
They share the same OEMs, and both are following the same ex-China
automotive strategy.
Renault has also been thumbing China recently for undermining EU
manufacturing as well [0] while China has returned to using Wolf
Warrior diplomacy against Europe [1][2][3][4] using the same
rhetoric that the Trump admin uses.
Of course, under the Xi admin China's foreign policy has always
viewed the EU as inferior and a has-been [5] and has become an
active participant in the Ukraine War [6][7].
Europe might not be able to trust the US, but it can't trust China
either.
[0] - [1] - [2] - [3] - [4] [4] - [5] [5] - [6] [6] - [7] [7] -
HTML [1]: https://www.reuters.com/world/china/renault-ceo-asks-eu-en...
HTML [2]: https://www.globaltimes.cn/page/202605/1361926.shtml
HTML [3]: https://www.chinausfocus.com/finance-economy/dear-brussels...
HTML [4]: https://www.globaltimes.cn/page/202605/1362161.shtml
HTML [5]: http://news.china.com.cn/2026-06/10/content_118541873.shtm...
HTML [6]: https://fddi.fudan.edu.cn/_t2515/57/f8/c21257a743416/page....
HTML [7]: https://www.reuters.com/business/aerospace-defense/russian...
HTML [8]: https://www.pravda.com.ua/eng/news/2026/06/12/8039041/
formerly_proven wrote 14 hours 40 min ago:
> following the same ex-China automotive strategy
Is that why Renault EVs (R5, Twingo) are wholesale developed in
China? Doesn't seem very ex-to me, more an in- type of strategy.
sofixa wrote 13 hours 1 min ago:
Why do you think the R5 was developed in China? Renault have
been quite open about all the improvements they had to make to
their processes, development centres and factories in France to
make it. The Twingo was partially developed in China.
alephnerd wrote 14 hours 38 min ago:
The EV batteries are sourced from Ampere and LG (in the EU) and
the EESM from Valeo (in the EU).
Sharing platforms isn't something EU manufacturers are opposed
to, but they do not want to be dependent on Chinese supply
chains. That is the crux of ExChina, especially as the majority
of an EV's value is derived from the battery and powertrain.
criticalfault wrote 15 hours 1 min ago:
only replying to the first link: isn't sourcing (buying or
manufacturing locally) parts for Chinese cars made in Europe a
good thing?
alephnerd wrote 14 hours 42 min ago:
It is, but the PRC has been pushing back against sourcing from
within Europe and only intends to use CDKs to assemble EVs.
This is what the EU is pushing back against.
What EU states are now lobbying for is if BYD wants to sell an
EV in the EU, it should include European originated parts. Just
assembling a knockdown kit in Hungary whose parts were all
manufactured in China is not "Made in Europe". If BYD or MG
wants to sell a BYD or MG car in the EU, they should source the
battery pack and powertrain from the EU.
Alternatively, the PRC can drop similar origination
requirements from it's domestic market.
The reality is the PRC won't back down, so they will be
tariffed by the EU, especially as the EU has lost patience with
the PRC due to their active involvement in the Russia-Ukraine
War [0], attempting to use diplomatic immunity to kidnap a
French national [1], and attempting to embargo the EU's rare
earth imports [2].
Additionally, it's easier for the EU to push back against China
versus the US while also winning brownie points in the US.
[0] - [1] - [2] -
HTML [1]: https://www.reuters.com/business/aerospace-defense/rus...
HTML [2]: https://www.lemonde.fr/societe/article/2024/07/02/deux...
HTML [3]: https://www.reuters.com/business/autos-transportation/...
w4der wrote 6 hours 17 min ago:
> Alternatively, the PRC can drop similar origination
requirements from it's domestic market.
Can you share any details on this? Is something I've rarely
seen discussed
Onavo wrote 1 day ago:
The main difference between this and your typical AC induction motors
(also magnet free) is that this is a DC motor so you need a commutator.
Your AC induction magnet free motors are very similar to drone motors
in that you don't have any electrically active moving parts like slip
rings and commutators. But for AC induction there will be a slight lag
(known as slip).
sinaa wrote 1 hour 36 min ago:
I iiiioiooo iko to keep up ok it iiiioiooo the same i
maxerickson wrote 1 day ago:
They are electronically commutated. The stator field is more or less
variable AC.
Onavo wrote 19 hours 9 min ago:
The inductance ones yes, not these ones.
dmitrygr wrote 1 day ago:
Seems to be: replace permanent Nd magnet with an electromagnet.
somat wrote 23 hours 27 min ago:
There is something... weird about this. this tech has existed.... a
long time. And I am not familiar with what is common in electric cars
so may be missing something obvious but thought this was already how
it was done. let me explain my limited understanding.
With ac motors electromagnets can be used in the rotor. there is even
a super clever way to do it where the electromagnet in the rotor is
driven wirelessly via induction. there are some downsides but having
no physical sliding electrical connection to the rotor is a huge
upside. The ac can be dynamically formed from DC via high speed
switching(transistors, in industry often called a VFD).
Due to the upsides of ac induction motors I sort of assumed this was
already what was found in cars. I am a bit surprised to find out
there were rare earth magnets in the first place.
cyberax wrote 21 hours 18 min ago:
AC motors are not magic. The core is essentially just a coil with
one turn, so it can generate only a very limited magnetic field. So
they have to be bulkier for a given power density and generally
slightly less efficient.
userbinator wrote 23 hours 20 min ago:
Permanent magnet motors are simpler and cheaper to make, at least
in the small (yes, small --- there are electric motors in the MW
range in industrial applications, which are themselves larger than
an average car) sizes found in EVs.
cyberax wrote 1 day ago:
They even use regular carbon brushes to supply power to the magnet.
Munro has a teardown video for a similar motor for Nissan:
HTML [1]: https://www.youtube.com/watch?v=BFmp9ODkCA8
dyauspitr wrote 1 day ago:
So does it consume significantly more electricity?
cyberax wrote 1 day ago:
Not really. The excitation power is a small fraction of the total.
The problem is that it makes the rotor far less mechanically robust
and also heavier. That's why these motors are less powerful.
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