Electric Vehicles

[bruto]

I wonder what the maximally efficient speed is for an electric car.

For internal combustion engine cars, from what I understand it's actually kind of complicated. I know that running the engine too slow is inefficient, but so is running the engine too fast. But I think it's even more complicated than just having a peak efficiency RPM. I've read about hypermilers who would accelerate to some high speed and then coast in neutral with the engine off until they slowed down, then accelerate again, rinse & repeat. That suggests that maximum energy efficiency for a gas engine occurs at moderate speeds but while accelerating, so that some of the energy is going to accelerating the car, it's not all going to fighting friction.

This may vary with how the car's engine is set up. I've read in various places that an engine set up to run at a constant middle speed can be most efficient, but that's party because it need not be able to accelerate and decelerate with expected driveability. That's the principle of diesel-electric setups, for example, and for engine driven generators in general. A lot of the inefficiency of automobile engines is in making them able to accelerate smoothly and work well at varied RPM, which used to require, in a carburetor, an accelerator pump (basically a squirt gun that throws extra fuel in) and presumably an equivalent enriching in fuel injection. Without it the car will burp when the throttle is opened quickly (as those of us old enough to have rebuilt a bunch of carburetors might recall).

Long ago I seem to recall a study done by BMW which suggested that the overall best economy was similar to what you've seen, except without the actual coasting. But the idea being that you accelerate to a speed slightly higher than what you want the average to be, then decelerate, and do this in cycles. Part of the rationale for that was that that initial burst of raw fuel on acceleration occurred less frequently.

 

[zooterkin]

That makes sense, so when you are at a total stop it lets you know the remaining range is infinity!

My car did recently show a miles per kilowatt hour figure of 999 (the maximum it can display). This was shortly after leaving my friend's house, which is at the top of a hill in Caerleon.

 

[novaphile]

The key thing for range is the effect of 'air resistance'.

This is why some early versions looked like cockroaches. (Going for a low flat shape to reduce the effect).

For my car, the optimum speed is probably about 50-60 kph, but air resistance ramps up insanely above 100 kph.

Looking online, I can see sites claiming that air resistance rises exponentially, so that the rate of increase is much higher between 60 and 80 mph, than it is between 40 and 60 mph.

This affects all vehicles, and is determined by vehicle shape.

Of course it is only considered an 'issue' if the vehicle is electric.

 

[Ranb]

I wonder what the maximally efficient speed is for an electric car.....

As far as I know it is about 20 mph for an EV. My F-150 is most efficient at 35 mph according to the mileage gauge. Wind resistance is a bitch to overcome. Double your speed and it's about eight times as high, maybe.

 

[JoeMorgue]

I wonder if that's part (part) of the issue. Truck owners really, really like modifying their trucks.

You can make the most amazingly drag coefficient low resistance truck you want but people put light bars and accessories and body kits and lift kits and camper shells on trucks more than they do with cars.

 

[8enotto]

The new Ute type car based trucks available in Mexico are already decked out with a slight lift over the base car models, bigger tires and more lights.
There are several from the usual suspects but one that stands out is the Renault Oroch.
Car like front aerodynamics but truck features built in.
It would make a decent chassis for an electric conversion if Nissan/Renault was inclined.

It's not the typical American brodozer required for carrying a medium load but as the smaller utility vehicle they shine.

 

[8enotto]

Dupe, sorry.

 

[Dr. Keith]

I wonder what the maximally efficient speed is for an electric car.

For internal combustion engine cars, from what I understand it's actually kind of complicated. I know that running the engine too slow is inefficient, but so is running the engine too fast. But I think it's even more complicated than just having a peak efficiency RPM. I've read about hypermilers who would accelerate to some high speed and then coast in neutral with the engine off until they slowed down, then accelerate again, rinse & repeat. That suggests that maximum energy efficiency for a gas engine occurs at moderate speeds but while accelerating, so that some of the energy is going to accelerating the car, it's not all going to fighting friction.

Internal combustion engines are most efficient (maximum power per unit of fuel) at wide ope throttle (WOT). Most stationary engine applications, such as compressors or generators don’t even have throttles. There is never a time where they are not running at WOT.

But for cars you only need WOT under very limited circumstances: 0-60 testing for car magazines. Most other times the engine will be running at less than WOT. That requires a host of compromises to engine design. That is one reason that engineers loved the idea of a hybrid that has the ice decoupled from the drive system, a pure generator setup. It allows a very efficient ice package, but can be jolting to the driver who is accustomed to engine speed and vehicle speed being coupled.

 

[jadebox]

Zero to 100 km/h in 1.4 seconds (or less):

 

[jadebox]

Overwriting a duplicate post ...

In my personal EV news, I recently bought a 2022 Hyundai Ioniq 5 Limited. The BMW i3 I had been driving was nice for going to work and back, but now that I am working from home, my needs have changed. I really don't need a car anymore. I could drive our SUV for the occasional trip to the store or whatever.

So, I did the logical thing and traded in the i3 for an Ioniq 5. After all, I am getting older and more attracted to shiny objects. While the i3 had an electric range of up to 70 miles on a single charge, the Ioniq 5 can only manage a little over 300 miles. So, I could probably drive to work and back for over two weeks without recharging the Ioniq 5 - if I was still driving to work.

So far I am very impressed by the new (to me) car. Like the i3, it is far larger than it appears from a distance and in photos. It is very comfortable and quiet. All the silly features noone really needs work well. I thought I would never use the remote parking feature, except when showing off. Then, one of the first times I drove the car, someone in a big truck parked really close to it. I used the Remote Parking Assist to pull it out of the space and avoid having to squeeze into it.

Plus, I really like the sort of retro 80's arcade game-themed styling.

 

[Filippo Lippi]

BYD sells more EVs than Tesla in Q4 of 2023

 

[Ziggurat]

As far as I know it is about 20 mph for an EV. My F-150 is most efficient at 35 mph according to the mileage gauge. Wind resistance is a bitch to overcome. Double your speed and it's about eight times as high, maybe.

I think the force of wind resistance is quadratic, so that at twice the speed, the force is quadrupled. The power lost is eight times, but it's the 4-fold increase in force that really matters since that's the efficiency drop. If the force were constant, energy per mile would be constant but power would still scale linearly with speed.

 

[Roger Ramjets]

I think the force of wind resistance is quadratic, so that at twice the speed, the force is quadrupled. The power lost is eight times, but it's the 4-fold increase in force that really matters since that's the efficiency drop. If the force were constant, energy per mile would be constant but power would still scale linearly with speed.

Correct. 8 times the power, but going twice as fast so 'only' using 4 times the energy to go the same distance - or would be if the vehicle only had to deal with wind resistance.

Tires can make a significant difference. My Leaf lost over 5% average efficiency when I replaced the special low rolling-resistance tires with cheaper standard ones (a calculated decision that I now regret!).

This is then balanced against the efficiency of the drive train. Gas engines are a lot more efficient at higher power output, so the system peaks at higher speed than electric motors, which maintain high efficiency at all but the lowest speed and/or torque.

Here's an efficiency graph of the 2011 Leaf motor. Over 90% everywhere except at very high torque/low rpm and low torque/high rpm.

Of course both gas cars and EVs are 0% efficient when idling, though even then EVs use less power because they don't have to keep the motor going. I once made the stupid mistake of not turning my Leaf off overnight. The next morning it had almost completely drained the battery!

 

[Roger Ramjets]

BYD sells more EVs than Tesla in Q4 of 2023

Over the year as a whole Elon Musk’s Tesla (TSLA) still outpaced BYD, selling 1.8 million electric cars. BYD sold 1.57 million electric vehicles

But...
China’s EV registrations in Germany in November: Nio 39, BYD 701, MG 2,577

The third sport goes to BYD, which registered 701 units... BYD sold 341,034 EVs in December globally...

The German government announced on December 16 that it is, with immediate effect, ending all EV subsidies known as the environmental bonus program as the country is facing a budget crisis. The program was initially supposed to continue until December 31. Many automakers announced they would compensate for the 4,500 EUR subsidy, including Nio, Tesla, Mercedes-Benz, Stellantis and Volkswagen.

Chinese electric vehicle manufacturer BYD to build factory in Europe, thus avoiding import tariffs

Now it’s official – BYD is expanding its network of production facilities in Europe and has decided to build its factory in the south of Hungary in the city of Szeged. According to the company, electric cars and batteries are to be manufactured there. However, no information has been provided about the extent of the investment or the expected start of production...

Since production costs in China are significantly cheaper than in Europe, the EU Commission has considered imposing import duties on Chinese electric vehicles. By building the new factory in Hungary, BYD is avoiding the planned punitive tariffs and is thus setting an example for the entire automotive industry.

 

[Segnosaur]

BYD sells more EVs than Tesla in Q4 of 2023

I have to admit, I had never heard of BYD before a month or 2 ago.

I am actually quite impressed with what I have seen... It looks like they are doing the one thing that North American manufacturers don't seem to understand: While Tesla, GM, ford, etc. are building High-end luxury vehicles crammed with all the features you don't necessarily need (like the Cybertruck or F150 Lighting or electric Mustang) seems to be concentrating on the lower range vehicles.

If they were available here in Canada, I might consider buying one. (Dependent of course on what charging standards they adopt, and available range..) Of course, purchasing a vehicle from a company based in China (with the various political and social issues that brings up) does raise a few moral quandaries. But then so does buying a Tesla (due to Elon "lets turn Twitter into a fascist hellscape" Musk) or any of the other traditional manufacturers (who all have their own skeletons).

Over the year as a whole Elon Musk’s Tesla (TSLA) still outpaced BYD, selling 1.8 million electric cars. BYD sold 1.57 million electric vehicles

True, but I think the important thing is the trend. The gap between the 2 companies for yearly sales has been narrowing going back to at least last year, and BYD won at the END of 2023, suggesting that if things continue the way they are they might end up beating Tesla for the entire year.

 

[Filippo Lippi]

The only stories about BYD in Canada I can see are about buses, sorry.

Meanwhile, sub-£20k ev coming to UK soon

 

[The Don]

Just bought another EV. In this case I've replaced a petrol powered mower with a rusted through deck with a battery powered one.

It's got good reviews, we'll see how it performs when mowing season starts.

 

[Segnosaur]

Just bought another EV. In this case I've replaced a petrol powered mower with a rusted through deck with a battery powered one.

It's got good reviews, we'll see how it performs when mowing season starts.

I've replaced my mower with one powered by biofuel.

It has the bonus of keeping those pesky neighborhood kids off my lawn.

 

[BowlOfRed]

Just bought another EV. In this case I've replaced a petrol powered mower with a rusted through deck with a battery powered one.

It's got good reviews, we'll see how it performs when mowing season starts.

I'm trying to talk myself into one. Unfortunately there's nothing wrong with my existing electric mower... other than the fact that I don't enjoy lugging the cable around to plug it in.

I've had it for at least 15 years. My cheapskateness tells me that I don't want to pay for a new one if the mower batteries don't last 15 years.

For things like mowers and my power tools (which get infrequent use), I wish I had a smart battery conditioner. I fear that if I just leave the battery on charge after every mowing that it won't last long.

How much mowing (in minutes) do you do? I have two unimpressive lawns, so I can finish in about 20 minutes of runtime per week (and another 10 minutes of unbundling, moving, and rebundling the power cord).

 

[The Don]

I'm trying to talk myself into one. Unfortunately there's nothing wrong with my existing electric mower... other than the fact that I don't enjoy lugging the cable around to plug it in.

I've had it for at least 15 years. My cheapskateness tells me that I don't want to pay for a new one if the mower batteries don't last 15 years.

For things like mowers and my power tools (which get infrequent use), I wish I had a smart battery conditioner. I fear that if I just leave the battery on charge after every mowing that it won't last long.

How much mowing (in minutes) do you do? I have two unimpressive lawns, so I can finish in about 20 minutes of runtime per week (and another 10 minutes of unbundling, moving, and rebundling the power cord).

50-60 minutes, weekly in early spring and late autumn - twice a week otherwise . The lawns are approximately 2500 square metres.