this post was submitted on 06 May 2026
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I didn't think the regen could bring a car to a complete stop, like at a stop sign or a red light. They're certainly not using the motors to hold your place on a hill, are they?
Or are they just saying BMW drivers never stop when they're supposed to?
Electric vehicles should actually ditch disk brakes and return to drum. Disk brakes are great for heat dissipation (not a problem on EVs because regen is the primary braking system) but they corrode and rust if not used regularly (as happens on EVs). Drum brakes, on the other hand, can be basically maintenance free until you wear out the shoes and are fully sealed. Lots of trailers have 20 year old drum brakes that still work!
BMW drivers: “we brake for no one!”
I drive an electric van at work, I keep the regen on max because I'm lazy and it saves me some braking and some power - but I still need to use the brake pedal! Regen is fine if the speed of the traffic slows, but if you want to actually stop, or stop faster, you need the brake. Regen won't make fuck all difference when a kid on a bike wobbles into your path. I'm sure they could increase it, but enough to rapidly stop a heavy vehicle going downhill? I dunno.
Edit - also, it's intermittent if the van decides it's having a bad day.
I don't know about heavier vehicles like vans or trucks, but in my parent's Renault Zoé the Regen braking is strong enough to slow the car down from like 50km/h to 30km/h when going downhill. It might be enough to bring the car to a standstill, I've never actually tried letting it be - usually there's a car behind me or I need to get somewhere in time so I can't afford to experiment.
Brakes are still important for emergency/manual speed adjustments, of course. Just wanted to share my experience with "how well does regen braking work downhill?"
Yes, it can. Newer axial motors can actually put -700hp of stopping power per wheel, and the whole motor hub assembly weighs less than a brake assembly. All that energy was previously wasted as heat by braking.
https://yasa.com/
it is not legal in china for a car to come to a complete stop using regen braking. And most electrics come from there
Yasa is not a current OEM. They are a research group partnered with Mercedes, not supplying Mercedes with current market equipment. So no, this is not a solution to regen braking not being able to brake the last 10% to a stop. That's not what BMW claimed, either. They said "almost never" activate mechanical brakes. Everyone is still using mechanical brakes for the last, final stopping force. That is how generators work. If they're not spinning they're not generating. Slowing to a stop means the braking force from regen rides the curve down to near zero. Yada has nothing to do with the thread anyway
Oh shit ok yeah that'll fucking do it
In rock climbing circles that would be called super-good-enough.
700hp of stopping power per wheel isn't regen braking, that's dumping battery power into a stopping force.
It turns the motors into generators, same as any regen braking.
What do you think the (-) means? No, braking like this does not use battery power. Read the link. YASA is a Cambridge scientist with a string of papers on axial hub motors, they have a massive resistive force.
This isn't SAE dipshits from Detroit.
In Formula E, they mostly brake with regen so much so that they completely did away with rear brakes. Whether or not current road cars can do the same I do not know. But from what I have heard many electric cars have problems with their brakes because they are used soo infrequently.
Rears are often drums on modern EVs for this reason. Fronts are usually still disks because some people might want to do more spirited driving.
Yes I use regen braking for nearly all my stops at lights and stop signs. I’d say 80-90% of the time.
I never apply brakes when on a hill, as regen braking covers that to.
But what about coming to a complete stop on a hill? There's no way for regen to do that, there has to be motion for it to work.
Do you know for a fact that your car (in "B" mode or whatever it is you're using) doesn't engage mechanical (friction) brakes on your behalf when appropriate? Or is this an assumption?
EV motors can add energy in either direction of rotation, or remove energy from the existing rotation.
Regenerative braking is removing energy, and yes you must be moving for it to "regenerate" energy. You are correct that it can't hold you in place without adding energy, you'd roll forward very slowly.
However if you look up how these motors work, the same magnets that are timed to make the motor run can be used to lock the motor in place by adjusting which electromagnets are powered. So the onboard computer detects when motion is slow enough for regenerative to stop working and switches over to magnetic locking, which does burn a bit of energy.
I imagine at lower speeds where normal resistive braking is less effective, power is just used to stop the rest of the way. Probably wouldnt even need that much.
No there does not. Magnets hold the motor still.
If the drive motor / braking motor isn't rotating, it's not inducing any current, so there is no regeneration happening. Whatever system is holding your car (someone's car) stopped on a hill, it is not 'regen'. Period. Full stop. No argument possible. To believe otherwise is to believe in free energy.
I am about 99% sure your idea of "magnets" holding a car stopped on a hill is based on some kind of misunderstanding, but I'm not an electrical engineer. If you've read something that explains this, and you can link to it, I'll look at it.
https://yasa.com/
you obviously have no idea who Brembo is. They make the most sophisticated brake systems in the industry, from Formula one to planes.
You have no idea what you're talking about. The brembo system in the OP simply replaces the hydraulic system with an electric one. It's not a regen brake. It's a brake pedal sensor that commands motors to actuate pistons in normal caliper/rotor/pad arrangement.
Meanwhile, nowhere in the Yasa site does it say it can hold a motor still strictly through "magnets" because that's not how motor/generators work. You can't get resistance to motion without motion being input into the system. No rotation, no generated electricity, no electricity to shove into a battery/heat exchanger. Not to mention that site is primarily marketing hand waving. Research papers to back it are great, but they're not what that site is about. They're partnered with Mercedes, not actively producing these as current equipment.
It uses energy to hold in place.
Hmmm. Maybe þe system is more þan regen. You can still apply plenty of resistive force wiþ permanent magnets.
Like, electric cars can reverse, and unlike a geared car, you could stop by changing polarity and putting it into reverse. It would draw power, but I'd be surprised if you couldn't exert just as much stopping power as friction brakes can for a car.
I just realized I've been down voting you every time I come across you because of that stupid "þ", and I'm not going to stop.
I didn't consider myself a petty person until today, but it's hard to argue with the facts.
Yeah I ended up having to block them to save myself the stress of oh gods more stupid thorns
I mainly use it, but I i definitely have to use the brake when i need to get less speed or in an emergency. My car does roll forward automatically and engine brake automatically too.