| ▲ | somewhereoutth 3 days ago |
| and would it be true to say that regenerative braking on electric cars reduces significantly this dust? |
|
| ▲ | coryrc 3 days ago | parent | next [-] |
| Absolutely. Nearly eliminates. Even non-plugin hybrids have greatly reduced. There was a "study" going around claiming otherwise, which sampled air captured by passing vehicles with a trash bag on a busy road, claiming EVs did not reduce brake dust, but even my brief summary here makes it extremely obvious how flawed this "measurement" is. |
| |
| ▲ | margalabargala 2 days ago | parent [-] | | For those of us unclear why collecting air from passing cars to measure particulates is obviously flawed, could you elaborate? EVs unfortunately do increase tire particulate, as well. Fairly significantly. It's not obvious to me that the decrease in brake dust isn't made up by the increase in tire dust. The removal of the tailpipe emissions is really where EVs shine from a pollution standpoint. If you turn on your car in your garage, you don't die anymore. | | |
| ▲ | coryrc 2 days ago | parent [-] | | EV brake pads don't hardly wear down, so they obviously can't have nearly the same amount of brake dust, yet the "study" showed they did. I'm guessing there's brake dust on the ground being kicked up. > EVs unfortunately do increase tire particulate, Fairly significantly In the USA, mass of EV is not significantly different than the alternative choice. EVs do not have increased tire particulate. If in Europe extremely lightweight tiny cars are actually a likely substitution for nicer, heavier EVs, then it seems reasonable that tire wear will increase proportionally. There's a lot riding on that "if" though. | | |
| ▲ | margalabargala 2 days ago | parent [-] | | It's not just the fact that EVs are heavier than the non-EV version of the same car, it's also that the regenerative braking means that the tires are dissapating energy that otherwise would have gone to the brake pads or to air resistance. Tires wear way faster on an EV, their lifespan in miles is generally much shorter. | | |
| ▲ | barnabee 2 days ago | parent | next [-] | | > it's also that the regenerative braking means that the tires are dissapating energy that otherwise would have gone to the brake pads or to air resistance This does not seem correct... - Air resistance slows the car without putting anything extra through the tyres (the friction is between car and air rather than between tyre and road) - Regenerative braking channels energy into the battery, and also heat, that would otherwise be dissipated by heating and ablating the brake pads and discs, but regardless or whether it's brakes or the the motor acting as a dynamo that puts resistance on the rolling of the wheels, for a given amount of braking you will have the same forces between the tyres and the road and the same tyre wear. So I'd expect it's only any additional weight that contributes to increase tyre particulates from electric care. Perhaps a tiny contribution from lower air resistance (on average at least) for electric cars, as there's often quite an effort to reduce the drag coefficient for range reasons, but I wouldn't expect this to be substantial as air resistance is not huge part of braking. | | |
| ▲ | margalabargala 2 days ago | parent [-] | | Regenerative braking needs something to act against in order to slow the car down. Whether the thing on the car side is an electric motor generating voltage or a brake caliper generating heat, the effect of both is to create resistance to the axle turning. This slows the car via tire-road friction. EVs tend to use regenerative braking, thus applying road-tire friction, much more often than an ICE vehicle uses brakes. In an EV if you are going tobfast and let off the accelerator, the regen braking slows you. With tires. In an ICE car, you will coast along and slowly slow down, mainly due to air resistance, unless you actively press the brake. If regen braking only happened when then EV driver pushes the brake pedal with their foot, your expectations would be correct and weight would be the only differentiator. But the single pedal driving design decision means the tires wear more. | | |
| ▲ | vladvasiliu 2 days ago | parent [-] | | But if the car decelerates harder when you let off the gas than you expect (compared to an ICE), maybe you'll give it a bit more "gas", so that, in the end, your deceleration is roughly the same in both types of cars? I haven't noticed EVs oscillating between full acceleration and hard braking when out and about. They seem to be driven pretty much the same as any other car. If I'm not mistaken, this means that tyre wear should be roughly equivalent (for an equivalent vehichle weight). So EVs still have the benefit of reducing brake pad wear. | | |
| ▲ | margalabargala 2 days ago | parent [-] | | The oscillation you mention does exist, it's just small enough that it's tough to pick out visually watching the car. But it can be felt within the vehicle, and the small oscillations are certainly enough to wear tires more than the ICE alternative. If you have any friends with motion sickness, ask them if it feels different to be a passenger in an EV. Alternately go to a tire shop and ask whether EVs wear tires faster. All this isn't to say EVs aren't better than ICE vehicles. They are, in many ways. It's just that tire wear isn't one of them. | | |
| ▲ | vladvasiliu a day ago | parent [-] | | > Alternately go to a tire shop and ask whether EVs wear tires faster. I'm convinced they do, many people noted this. But I always thought it was mainly because the cars are heavier than what most people are used to, and they also have much better acceleration. | | |
|
|
|
| |
| ▲ | bryanlarsen 2 days ago | parent | prev [-] | | The engines are absorbing the energy that would have otherwise gone to the brake pads. Tires apply the braking force to the ground in exactly the same manner on both EVs and ICE vehicles. | | |
| ▲ | margalabargala 2 days ago | parent [-] | | Firstly, the motors absorb half the energy. The other half goes to the tires. It would be great and efficient if the motors could.absorb it all but unfortunately physics doesn't work that way. Secondly, if you've ridden in an EV, you would know that the drivers/cruise control often apply regent braking in situations where an ICE vehicle would have simply coasted to a stop. Hence more wear. | | |
| ▲ | two_handfuls 2 days ago | parent [-] | | The tires wear the same amount here because either way, the car decelerates by the same amount at roughly the same rate. | | |
| ▲ | margalabargala 2 days ago | parent [-] | | No, it doesn't. With the ICE car, if you want to go 55, you might accelerate to 57 and then coast down to 55 without using brakes. With an EV you might accelerate to 57 and then brake to 55 when you let off the accelerator. Tire wear is a function of how often you use your tires to slow down the car. With an ICE car that's every time you hit your brakes. With an EV that's both brakes and regen. An EV's time spent braking or regenning is more than the time an ICE car spends braking. Someone could design an EV that behaves the way you describe, but aggressive regen sells better, so no one does. | | |
| ▲ | rogerrogerr 2 days ago | parent | next [-] | | > With an EV you might accelerate to 57 and then brake to 55 when you let off the accelerator. No one with more than a few miles of one-pedal driving would do this; it’d be highly unpleasant. What actually happens is you remap your pedal inputs: all the way off is braking, somewhere in the middle is coasting. Your brain will do it automatically and OPD is far more pleasant than two-pedal driving after a trivial learning curve. | | |
| ▲ | margalabargala a day ago | parent [-] | | I agree that OPD is better. I disagree that it's easy to coast with OPD. What actually happens is you wind up decelerating for curves, accelerating on straights more, and otherwise having better control of the car. Holding the pedal in a location where power is neither going to or coming from the motor is very difficult; usually you want power going to the motor anyway to overcome air resistance. Also, consider that most EVs will automatically regeneratively brake when going downhill with cruise control on. The last ICE car I owned just coasted and would speed up on large downhills with cruise on. |
| |
| ▲ | bryanlarsen 2 days ago | parent | prev | next [-] | | > With an EV you might accelerate to 57 and then brake to 55 when you let off the accelerator. No you don't; in fact you can't. Letting off the accelerator enough to apply regen is going to take far more than 2 mph off your speed. If you want to drop from 57 to 55 in an EV its done the exact same way you do it in an ICE vehicle: you coast. | | |
| ▲ | margalabargala a day ago | parent [-] | | Of the three EVs, all different manufacturers, that we've owned in the last decade, zero have coasting as an easy option. You have to either switch off OPD entirely, or else literally shift the car into neutral. And yes, you are right, if you do that you can coast and then your tire wear will be no worse than an ICE vehicle. Most EV drivers don't do those things. | | |
| ▲ | bryanlarsen a day ago | parent [-] | | Yeah, you're not shifting into neutral on your ICE car to coast from 57 to 55 either, you're just releasing the accelerator. You've still got the motor engaged, so you're doing mild engine braking on the ICE even if it's vernacularly called coasting. | | |
| ▲ | margalabargala a day ago | parent [-] | | Thanks to the magic of automatic transmissions, there's basically no difference! Certainly not enough to make up the EV tire wear from regen. |
|
|
| |
| ▲ | two_handfuls 2 days ago | parent | prev [-] | | Coasting wears your tires too. By the same amount. | | |
| ▲ | margalabargala 2 days ago | parent [-] | | That's...just completely false. If you lack the middle-school-level understanding of physics to understand why, I'm not going to be able to give it to you in an internet comment. Think hard about why braking and coasting would wear the tires differently. Here's a hint. Where does the energy go? What is doing the work to stop the car in each scenario? |
|
|
|
|
|
|
|
|
|
|
| ▲ | thmsths 3 days ago | parent | prev | next [-] |
| I recall a discussion on HN explaining that while true, this might be offset by the higher average weight of EVs, leading to more dust from the tires and the road. Again, no easy solution unfortunately, just trade offs. |
| |
| ▲ | coryrc 3 days ago | parent | next [-] | | And to add info, an F-150 will change brake pads 3-7 times over 200k miles, while a Model Y will still be on the original set with nearly no sign of wear. | | |
| ▲ | fsckboy 2 days ago | parent [-] | | but compare the wear of the tires, and weigh tires vs brakes by the amount of "total pollution delivered to the environment", i.e. 20% more wear of something that is 2x as polluting is 40% more pollution. I don't know the numbers or the answer, I'm just saying it's not as simple as your statement makes it out to be. | | |
| ▲ | coryrc 2 days ago | parent | next [-] | | Why are you just making up numbers then saying "it's not as simple"? Try educating yourself a little first instead of just jumping to conclusions which reinforce your existing biases. | |
| ▲ | brailsafe 2 days ago | parent | prev [-] | | > 20% more wear of something that is 2x as polluting is 40% more pollution If an equivalent car wore down its tires 20% slower, and those tire particles contributed 2x the intensity of pollution than other types of wear-based pollution, than the increase in produced pollution from that source seems like it would be ~16%, not 40%. If one car drives 100 km and produces 2 units of pollution per km, that would be 200 units. Another car wearing 20% more would produce 240 units, or roughly ~16% more. | | |
| ▲ | yunwal 2 days ago | parent [-] | | > Another car wearing 20% more would produce 240 units, or roughly ~16% more. This is some Fermat’s Last Theorem shit |
|
|
| |
| ▲ | iambateman 3 days ago | parent | prev | next [-] | | If that were true of tires, you would expect an EV’s tires to get substantially less range before wearing out…which I don’t believe is the case. | | |
| ▲ | rconti 3 days ago | parent | next [-] | | IME they only wear out maybe 15-20% faster than you'd think. On the other hand, over the span of 40,000 miles, a tire loses a LOT more rubber by weight/volume than a brake pad loses pad material. No idea what the PM2.5 breakdown is though. | | |
| ▲ | bryanlarsen 3 days ago | parent [-] | | The difference is that only about 1% of the worn rubber ends up in the air whereas most of the brake pad ends up in the air. Most of the worn rubber stays on the road. Where it will get washed away by the rain to end up as microplastics in the water. |
| |
| ▲ | pif 3 days ago | parent | prev [-] | | It is actually the case! That's why your choice of tires on online sites gets so smaller as soon as you tuck the "electric/hybrid vehicle" case! | | |
| ▲ | t_tsonev 3 days ago | parent [-] | | Specialized EV tires are also optimized for drag and noise, wear is just a factor. Anecdotally speaking I'm at over 80k km on a set of EV tires with at least 20k more to go. The issue has more to do with driving style and engine power than any other factors. | | |
| ▲ | l1tany11 3 days ago | parent [-] | | 100%. Tire technology is a real thing. Tires have advanced a ton in the last 10 years. But driving style is the biggest thing. Some people can only get 10k miles out of a set of tires, while others with the same car and tires get over 40k. But they do care about tire wear a lot, they know the acceptable wear life for the class. A couple years ago I bought a set of Pirelli tires that were ~50% off because they were an older version; hoping I’d get some benefit. Unfortunately they had half the life and were a bit worse in every way than the newer tires I had before and after. | | |
| ▲ | bob1029 2 days ago | parent [-] | | Some tires are going to wear fast no matter what. I had some Pirelli PZero summer tires that I could never get more than 15k out of regardless of how I drove. The tire compound was very soft and sticky. If you have something like really high performance tires, I recommend just using them. The grip is always there and you are always paying for it. As long as you aren't losing traction constantly, the difference is negligible in my experience. |
|
|
|
| |
| ▲ | coryrc 3 days ago | parent | prev | next [-] | | Additional weight (which is minor; of best-selling vehicles, F-150 curb weight is 4000-5600 lbs, Tesla Model Y is 4400-4600 lbs) does not meaningfully increase brake wear because the brakes don't get used. | |
| ▲ | rcpt 3 days ago | parent | prev [-] | | That sounds like a stretch tbh |
|
|
| ▲ | earlyreturns 2 days ago | parent | prev | next [-] |
| I’m guessing not as much as standard transmissions, which largely eliminate the need for breaking while also reducing fuel usage. Yet there are almost no new cars with standard transmission. If only people cared a bit more. |
| |
| ▲ | bryanlarsen 2 days ago | parent [-] | | You guessed wrong. An electric car can use its engines to bring a vehicle to a complete stop. It can also use the motor to hold the car in place, even on a fairly steep incline. You can't do either with a standard transmission ICE vehicle. There are people with electric cars that have their brakes rust out because they're never used. A standard piece of advice to EV owners is "make sure to use your brakes at least once a month". |
|
|
| ▲ | kjkjadksj 3 days ago | parent | prev [-] |
| You can get this lack of brake pad use with an ice with a manual transmission as well if you engine brake. |
| |
| ▲ | shayief 2 days ago | parent [-] | | the engine cannot brake to a complete stop, so break pads are always in use. At low RPMs, the engine is going to stall (manual) or switch to neutral (automatic). | | |
| ▲ | bob1029 2 days ago | parent | next [-] | | Brake wear scales ~quadratically with vehicle speed. Applying them at 5mph vs 20mph is 16x less energy to burn off. | |
| ▲ | kjkjadksj 2 days ago | parent | prev [-] | | It can brake to nearly a complete stop though with the brakes basically holding the car in place at the end. I got pretty good at it. |
|
|
