Comment by ZeroGravitas | Hacker News Reader

Comment by ZeroGravitas | Hacker News Reader

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EVs are actually phasing out both brake particle emmissions and brake fluid, by returning to "drum brakes" when regen isn't enough.

https://www.continental.com/en/press/studies-publications/te...

> The drum brake offers even further attractions, the environmental particulate emissions are vastly reduced when compared to the traditional disc brake system technology, that will bring upcoming decisive decisions to comply with increasingly stricter environmental requirements. While combustion engines have had to comply with increasingly stringent emission limits in recent years, the focus has now widened to include foundation brakes. The fine brake dust generated from the brake system can have far-reaching adverse effects on human health, depending on the size of the particles emitted. Experts expect stricter legal requirements from the EU Commission by 2025 at the latest. Drum brake technology takes advantage of the enclosed housing system, allowing the brake dust particulates to be accumulated within the enclosed system that can be collected and disposed in a controlled manner that protects the environment.

EV’s greatly reduce brake wear. We live on a mountain, and typically apply the brakes for 1-2 seconds to get down with the EV. We ride the brakes for 1 or 5 minutes with our manual or automatic transmission ICE car. Put another way, we’re pushing 50K miles on the EV’s original brakes and replacing / servicing them isn’t on our radar.

However, the EV eats tires like a full-size pickup truck with somewhere to be.

> However, the EV eats tires like a full-size pickup truck with somewhere to be.

Out of curiosity, why is that?

Edit: I Google’d:

“ Electric vehicles boast instant torque, meaning they accelerate the second you put the pedal to the metal. However, the high instant torque of electric vehicles can also increase wear and tear. In addition to good grip, the rubber compound used for EV tyres also needs low rolling resistance.”

And

“ Teslas are heavier than most other cars because of their battery packs, which can add hundreds of pounds to the vehicle's overall weight. This extra weight puts additional strain on the tires and leads to increased friction between the tires and the road surface, which causes them to wear out faster.”

That seems like a temporary issue. Right now we've still got lots of expensive/high class EVs where ludicrous mode is a thing people are excited about, but once there's real competition on the low end... "doesn't waste tyres" sounds like both a good selling point and simple to implement.

I think we are already there. The best selling Tesla right now is also a slowest Tesla ever made - Model Y SR at pretty limpy 0-60 of 7s (which is perfectly fine and fun to drive).

p.s. Seeing how many people already killed themselves with Plaid - I think gov should require advanced driving licence for super quick and super fast cars.

Advanced driving courses have a decidedly mixed record on improving safety, unfortunately. I believe the evidence suggests that they improve confidence more than they improve skill.

As for the Plaid, from what I’ve read the yoke and the high-speed handling are frankly dangerous. If somebody gave me one, I’d sell it and buy something where the drivetrain, the handling, and the aerodynamics are better matched.

It’s just too hard to resist pulling out of an intersection with lots of acceleration. I’ve more than a few times heard my wheels squeal going from stop to 25 in a couple seconds.

I am under the (maybe wrong?) impression that the former issue is helped a lot by telling the car to accelerate in Chill mode instead of Standard, which causes it to purposefully carefully ramp a derivative or two of acceleration.

It helps less than you’d think. Part of the issue is that the tires are ultra low rolling resistance, and part is that the car weighs an extra ~500 lbs.

The car weighing a lot is the second issue, though, not the first. Is the ultra-low rolling resistance a third issue, or related to one of the other two?

> Electric vehicles boast instant torque, meaning they accelerate the second you put the pedal to the metal. However, the high instant torque of electric vehicles can also increase wear and tear.

It seems like this factor could be easily solved with torque output adjustments, but it won’t be unless it’s regulated.

The unwashed masses now expect every BEV to be performant without knowing the maintenance costs of actual ICE performance cars.

Manufacturers feed into this, as dealers love to have repeat customers for an otherwise low-maintenance car.

Huh? BEV maintenance costs are way lower than ICE, even if brakes and tires need replacing a little earlier than the ICE equivalent.

While watching this video I was thinking will this solve the tyre particulates problem

https://youtu.be/vSNtifE0Z2Q

No way, the grip on a normal road with those tires would be terrible. They would also be destroyed very quickly. They are designed for off-road low-speed applications. Low rolling resistance rubber tires are much more efficient energy wise as well. Rubber tires are very advanced anyway, many use chlorobutyl blends and steel and/or Kevlar reinforments.

"Compared to a similar ICE vehicle"

It maybe a false memory effect but I vague remember this notion about trolleybuses.

> we’re pushing 50K miles on the EV’s original brakes and replacing / servicing them isn’t on our radar

50k is nothing, ICE cars often go longer than that without new brake pads. Had my ICE sedan for five years with no sign of brake squeaks yet. Never thought about brakes when I lived on a huge hill either.

The OP lives on top of a mountain. Brakes don't last 50k if you have to ride them for 5 minutes every time you leave home.

> Brakes don't last 50k if you have to ride them for 5 minutes every time you leave home.

You should never ride the brakes for minutes at a time! Even if didn't care about wear, the main problem is they will overheat and become less and less effective so if you suddenly need to brake harder during that downhill, you may have little to no braking power.

Always use engine braking if faced with a long steep downhill. Use the brakes occasionally to modulate speed but never ride them continuously for a prolonged time.

If you ride your brakes down a mountain, you are doing it wrong. Engine braking predated electric cars by quite some margin.

I think most EV drivers will tell you that they use the brakes very infrequently - perhaps once or twice per hundred miles if one is driving long distances. Certainly if you're careful it'd be possible to never use the brakes. I think that's what EV owners think of as different to traditional cars. Yes, brakes can last a long time on traditional cars, but it seems intuitively obvious that if you're just not using them, they'll last longer for the same equipment.

Manual transmission drivers say the same.

> We ride the brakes for 1 or 5 minutes with our manual

We can excuse the brake riding in the automatic, but why not just downshift the manual?

These things rust as hell in their enclosures. Volkswagen group EVs with rear drums are catastrophic development. Take press releases and advertisement with a grain of salt next time.

Until perhaps 10 years ago, drum brakes were standard as the rear brakes of almost every car. They lasted pretty much the lifetime of the car.

> Until perhaps 10 years ago, drum brakes were standard as the rear brakes of almost every car.

You need to go back more than that. In the 80s nearly every car had rear drum brakes, that phased out in the early 90s or so. Only the very cheapest cars had drums past that timeframe.

> They lasted pretty much the lifetime of the car.

Having owned a few drum braked cars (including all four wheel drums), not really. You still need to change them as they wear out, it's just a lot more work than disk brake pads which can be swapped out in a few minutes.

The rear brakes do a lot less work than the fronts, particularly on smaller lightweight cars (the kind that still had rear drums in the 90s) so in that sense yes, those rear drums lasted a good while (but certainly not the life of the car).

If you put front drum brakes on a fast & heavy car, you'll be wearing them out pretty quick.

Maybe that’s specific to big US cars? Drum brakes are still completely standard on entry level european and Asian models. Rear discs only come into play when you’re going above 100hp and/or 1300kg

Front disk brakes came into widespread use in 1960s and for a good reason.

They are more efficient (read: safety) and much easier to maintain.

Rear brakes are almost redundant on entry level cars except for the parking brake. You can just disconnect them and not notice any significant change in handling.

Yes, I haven’t seen front drums in at least 20 years

The Honda Civic Si went to four wheel disk brakes in 1992, over 30 years ago.

Last time I had to touch drum brakes was in 1991 and I'm very (very very) happy about that. Drum brakes are a maintenance nightmare I never again want to experience. I'd rather adjust carburator jets all night before working on drum brakes again.

Yes. My cheap motorcycle had drum brakes and was fine for many many kilometers. The problem with electric vehicles is that they brake with motors and not with brakes. Brakes gather dust and silently corrode. Apparently latest vehicles periodically activate brakes without driver’s intervention to prevent corrosion and uneven wear.

And EVs with regen, brake usage is also vastly vastly reduced as well. Most folks aren't replacing their disc brakes in their EVs either until very high mileage unless they're hard on their cars.

10 years ago? As in 2013? Did you mean 40 years ago? Almost every car? On a scale of 1 to 10 billion, how high are you right now?

Rear drum brakes are still standarx for entry level cars in Europe. Dacia Sandero, Renault Clio, Peugeot 208 - the base models all have rear drums

running a 40 year old car (ev conversion) with drum brakes just fine. its a solved problem.

Nobody who has ever worked on drum brakes wants to go back. Nevermind the heat and weight issues.

> Nobody who has ever worked on drum brakes wants to go back.

This. Drum brakes are an inordinate pain to maintain and adjust.

I can change pads in disk brakes on all four wheels in less time that it took me merely to remove the drum from a single wheel in older cars.

Cute.

How does the accumulated brake dust not affect braking performance? And can it tolerate getting wet inside, or is it somehow sealed well enough to go through puddles without getting wet?

I suppose one could build an all-wheel-drive EV that only uses mechanical brakes during emergency maneuvers.

Drum brakes have been around for a century, afaik they're more robust than discs but "lower performance". These look like a variation on a pretty standard design at first scan.

I’ve never played with a drum brake, but I’ve assumed that dust is ejected somehow in normal operation. The Continental design is sealed to contain the dust.

Maybe dust in the drum isn’t a problem? Or maybe it’s designed so the dust accumulates somewhere other than on the friction surface inside the drum?

Lower performance brakes is a hard trade off to make when EVs are also heavier than gas cars

I think the idea is that engine braking (regenerative braking) makes up for the difference.

Can you rely on that if someone charges their car at elevation and then has to drive down a mountain?

Yes, by not charging to 100%, so you have some room for additional charging by regenerative braking. Virtually all EVs come with a setting, usually enabled by default, that stops the charge at a preset percentage, like 80 or 90%. Chevy aptly calls theirs "hilltop reserve".

My PHEV weighs 30% more than the non-PHEV version, yet my brakes have lasted longer than anyone I read online with the regular version of my car.

This is because of regenerative braking not using the brake pads, using the motor instead.

Drum brakes are one of the many things that contribute towards EVs becoming lighter than equivalent ICE cars over time, as they weigh less than disc brakes (about 25% lighter, 10lbs maybe, and unsprung weight too).

As the link states, they also increase efficiency, and that allows for smaller batteries, less weight. They're also looking into lighter weight aluminium disc brakes because EVs use them less, and it prevents issues with low usage disc brakes rusting.

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