Related recent HN discussion:
58 days ago: "Another way electric cars clean the air: study says brake dust reduced by 83%" (103 points | 184 comments): https://news.ycombinator.com/item?id=44113256
Electric cars produce less brake dust pollution than combustion-engine cars
751–760 of 783 posts
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#752I dream of a future where societes manage to price in all externalities into the objects they produce. This of course requires us to be(come) more honest about the hidden costs to society each and every objects and its usage brings with itself. What we do with that knowledge is another question, but right now my feeling is a lot of bad actors skew the picture to make themselves look good while regular people are left…
Tricky to do accurately though. Like a car driven occasionally in the countryside may cause little damage from brake dust, a cab in a city center a lot.
Not necessarily: You get a mix of average representative driving profiles, drive that with a vehicle and measure how much particles are emitted. This is how exhaust emissions are already measured.
In practise the biggest danger is that manufacturers game that system like VW did by recognizing a test environment and adjusting accordingly.
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#753Earlier quoted context omitted.
>On paper, yes, but did that ever happen? Like absolutely, unless you consider 1.4L petrol engine large for something with over 170KW (over 220hp). Such kind of offerings are quite common at the East side of the pond.
I'd consider engines with HP in the two digits range not big. Few ICE cars (hybrid or not) are ever accelerated at the rate you could achieve with a 75 HP engine revved into the high but still safe range. People buy big engines so that they can get all their acceleration needs served at half throttle. And that's for stick shifting, those on automatic pick engine size so that they can accelerate on quarter throttle or…
Hybrid one - 0-100km/h sub 7sec. The most important part is not 0-xxx but being able to take trucks in relatively short distances b/c most roads features just two lanes. Pressing pedal to the metal and engaging both engine does that.
The sub 100 power doesn't mean much if the engine has a turbine, e.g. TSI of volkswagen
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#754Earlier quoted context omitted.
The EU2200i can sustain 15 amps. That charges most EVs at something like a few miles of range per hour. The biggest one that’s small enough for a frunk is the 3200i, which still only sustains 21.7 amps - plus, that’s from an L5-30R socket, so you’d need an adapter for the EV, and a custom chip to limit charging current below that, since the ones I’ve seen for that socket assume they can pull 24 amps. Re: maintenance,…
> The EU2200i can sustain 15 amps. proverbial
I’ve ran mine at nearly that for hours without any issue. Honda generators do what they say they’ll do.
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#755Earlier quoted context omitted.
> […] but there can also be a significant benefit from allowing the ICE to remain in the RPM "sweet spot" rather than moving around a larger range. Which is why I'm surprised electric cars with range extenders aren't a bigger thing: * https://en.wikipedia.org/wiki/Range_extender Have the powertrain be all-electric, and have a battery pack, but for those with range anxiety have a small generator as an option that woul…
BMW tried that with the i3, it wasn't particularly popular. An engine, fuel system and a generator are all relatively complex additions compared to just putting the same cost and vehicle space into more batteries, and the public charging networks are definitely up to the task by now (having been EV-only for almost 5 years now).
> An engine, fuel system and a generator are all relatively complex additions […]
And yet that's what an ICE car is.
So a range extender (RX) should be no worse than ICE: in fact a little less complex because you don't have a gear train and transmission.
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#756Earlier quoted context omitted.
I mean, we are comparing 6-8 to effectively infinite? Question then comes into just how much is lost by being outside of the sweet spot for an engine. Which, I agree that I would not have thought it would be that big of a deal. Just going off modestly paying attention in my car, I see massive benefits keeping the car around 300 rpms lower. Interestingly, my car gets better gas mileage around the 40ish speeds than I d…
Generally speaking your car will get better fuel economy at 40mph than it will at 60 or 70mph. Your car gets so much more wind resistance the faster you go. The main reason why city mileage is usually lower is because of all the stopping.
I think I just mentally had this idea shifted up about 10-15 mph. I'd expected 55 to be the sweet spot, for some reason.
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#757Earlier quoted context omitted.
My cheap EV gets 200+ km of range (124 mi) from 20 minutes of charging. Again, why the hell are you talking about two hours. Why are you saying that 20 minutes gets you "home". Why are you talking about charging from 0 to 100 % when that's NOT how you charge an EV, ever. Sounds like you've never driven one.
No. It doesn’t. Your display says that. And your display is bullshit. I work with the people that make the displays man. There are entire groups dedicated to deciding what is indefensible lies, and what “could be true under the right circumstances so we’re allowed to say/show that” > Why are you talking about charging from 0 to 100 % when that's NOT how you charge an EV, lol, go to a charging station sometime and see…
> Your display says that. And your display is bullshit.
I don't know what to tell you. I drive a MG4 with a 64 kWh battery. My average consumption is usually between 14-15 kWh/100 km (I don't drive very fast on freeways), which means that a full battery gets me a bit over 400 km, which is the actual range I can get fro the car. It charges at 135 kW for a large part of the battery capacity and 20 minutes of charging gives me more than 50 % of the capacity, hence more than 200 km.
> lol, go to a charging station sometime and see the people sleeping or watching tv
I live in Prague, Czech Republic, in Europe. I don't see people sleeping or watching TV at charging stations, because there's a ton of them and they're in convenient places. I have never waited for an empty spot, not a single minute. I park my car on the street, I'm entirely reliant on public infrastructure and it works well.
> If it’s your primary vehicle and you want to go somewhere, you are going from 0 to 100.
My EV is my only vehicle and I only charge it to 100 % when I need the battery to balance (which my car only does at 100 %), i.e once every month or so. Again, with a working charging network and a reasonably modern EV, you can just start driving and charge when necessary (for 15 minutes or so).
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#758Earlier quoted context omitted.
I've ridden in one and this was basically a case of "you get the worst of both worlds". The engine was small and running at a constant RPM, leading to an annoying noise in the cabin. The range extension was not particularly huge. Worse, when we did eventually run out of battery on one trip, the range extender was unable to recharge the battery after refueling the car, forcing us to scramble to find an available charg…
>> the range extender was unable to recharge the battery Could you expand on this? What was the actual problem? For example, did the range extender start and run? Did it put any energy into the battery at all?
We ran out of battery and fuel (I was on the backseat so I don't remember the exact sequence, I just remember the car basically losing power without much warning on the autobahn). The car was towed to a gas station were we proceeded to refill the tank, but the range extender would not start and the car computer was adamant we had to recharge. Which led to a quest to find a public charger in the middle of the night, after 2 failed attempts, we gave up and asked to be towed to our destination instead since it was close enough.
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#759Earlier quoted context omitted.
Ah, thank you, I see the argument. I'm still a bit skeptical though when many non-CVT automatics are 6 or 8-speed models that there would be much "sweet spot" benefit left by being able to make relatively small changes in engine speed. Like many things probably depends on exactly what comparison is being made.
I mean, we are comparing 6-8 to effectively infinite? Question then comes into just how much is lost by being outside of the sweet spot for an engine. Which, I agree that I would not have thought it would be that big of a deal. Just going off modestly paying attention in my car, I see massive benefits keeping the car around 300 rpms lower. Interestingly, my car gets better gas mileage around the 40ish speeds than I d…
Best efficiency speed can be understood by considering impact of fixed losses like HVAC, lights, computing, which consume more energy the longer you drive (so the total energy for those would be minimized by going faster) and the aerodynamic losses in which force goes with speed squared, power w/ speed cubed, energy over a fixed distance back to squared because at higher speeds time is reduced (this component is theoretically minimized by going very slowly). In between is rolling resistance which requires a fixed energy per distance, so it doesn't care about speed.
For EVs, the drivetrain efficiency is so high that it's variability with operating point doesn't affect this calculation much, and so the most efficient speed of an EV is around the speed at which the fixed losses equal the aero ones. This will vary greatly with environmental conditions since AC or heating load can be large in hot or cold conditions but at the right temperature will go to near zero.
In ICE cars, the drivetrain efficiency is much lower and so the drivetrain efficiencies are a much more significant part of the optimization problem, but the basic physics of the aerodynamics are the same.
The model I used to use in my head is that for an ICE, the most efficient operating point is probably around the lowest speed the car can operate in the highest gear, so maybe around 40 mph / 60 km/h? Obviously a rough heuristic though.
Re: Electric cars produce less brake dust pollution than combustion-engine cars
#760Earlier quoted context omitted.
On paper, yes, but did that ever happen? Sorry for being sarcastic, but where I live the frugal hybrid is exceptionally rare and the "same big engine, but driving a much heavier car" hybrid is omnipresent. The kind of people who might buy the frugal one buy second or third hand while almost all buyers of factory new pick the "same big engine" option, and those are the ones who decide what's available on the second ha…
> did that ever happen? In 2010 with the Chevrolet Volt.
Which only had a 1.4l engine. It was not as efficient as the gas only Prius but could be more efficient overall as the Volt of 2010 had a 40 mile EV range.