this post was submitted on 23 Mar 2025
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Still more energy efficient than a regular ICE car.
Debatable, it depends on what fraction of the power was supplied by the generator. The chemical-kinetic-electric energy conversion incurs great losses because of waste heat, and portable diesel generators are not always built with efficiency in mind. A charging station operating on 100% diesel to power an EV is much less efficient than a modern ICE vehicle of a similar mass sans batteries.
Citation needed. Do ICE engines not get hot and therefore also have great losses because of waste heat?
Presumably a generator making electricity for a charging station would only run when electricity is needed, while an ICE engine would be losing energy to heat the entire time the vehicle is idling in traffic.
Why would a diesel generator not be made to efficient and why are ICE engines always made to be efficient? How do you know which kind of generator they were using? Why would they use the generator for 100% of the energy needed?
Keeping in mind that this is a hypothetical scenario and that I did point out that the overall efficiency is dependent on how much of the power is generated by renewables and how much by the on-site diesel generator:
It doesn't really matter actually. Electric motors are so much better at delivering power, that you will get more range from a gallon of gas by towing an 'flat battery' EV behind a truck and then driving the EV than you will just driving the truck without towing the EV.
Doesn’t that highlight the torque that is available and delivered, more than efficiency of the electric motors, charging, heat losses, etc.?
There has to be a better example to prove your point than this.
Nope.
Yes it gets also hot, but the battery as well, during charging and using.
To clarify, ICE produce so much waste heat that defrosting and heating your car is essentially free (energetically speaking) because the car needed to dump that excess heat anyway.
BEVs don't even generate enough waste heat to maintain the battery temp, and frequently rely on heaters to maintain battery and cabin temperature.
So saying BEVs create waste heat too is technically true, but it seriously undersells the scale of difference between the BEV and the ICE.
We would just put diesel generators in the trunk if any of that would make sense.
No, an electric car powered by a Diesel generator is definitively not more effective than a combustion car.
The thought doesnt even make sense, since a Diesel generator is a combustion engine.
We actually do. The BMW i3 came with a gas generator as an optional range extender feature. It was not very popular. The majority of drivers drive less than 40 miles a day, and EVs easily encompass that distance, even if you have to run the heat.
And yes, an electric vehicle powered by a combustion motor absolutely is better in terms of efficiency down to extremely small scales. We've been using diesel electric vehicles for decades now because of their efficiency, torque, and long service life. They're called 'trains'.
Holy smokes, is this bizarro world?
Youre arguing against the principle of physics.
What makes a Diesel generator better then .. Checks notes... a Diesel Generator?
By your logic it becomes better when it's used to charge a battery first.
We are comparing attaching a diesel engine via a gearbox to attaching it via generator and electric speed controller.
Electrically driven wheels can deliver just the right amount of power at over 95% efficiency. Direct ICE suffers because it cannot always run the engine in ideal conditions, reducing its efficiency.
We do this in locomotives but not in cars because cars need to be lightweight. Actually, nuclear is clearly the best vehicle propulsion, almost infinite range and high power. It is only used in ships due to its weight.
I cant find a source for your claim, the best I could find Was that they can be more efficient under circumstances than diesel mechanic Systems. But it seems to be at least close. Do you have a source you can link?
The reasons theyre the choice number one are different. The Main reason, it doesnt have a Transmission and is easier to repair, while there's also less parts that can break.
I'm not claiming that electric transmission is more efficient always because it isn't. But as you say it is close.
In a scenario where a train drives at a constant speed forever, attaching the engine to the wheels directly is a clear winner.
However, with varying torque requirements, an ICE can't always operate at maximum efficiency. They are especially bad at starting from a standstill. You can get a good overview of the concept from this wiki article. https://en.m.wikipedia.org/wiki/Power_band
You arent, but that's how the discussion started and why I joined that discussion.
Ive earned quite a bit though, because I was not entirely correct myself.
Yeah, I guess a multi-billion dollar logistics operation has purchased expensive less efficient locomotives for decades because they're physically impossible... Or your armchair understanding of physics is wrong. Wonder which one it is?
What? Your Argument is that it's more efficient to charge an EV with a diesel generator than using it to combust in the car directly.
And that's just flat out wrong.
Im not biting on your fast goal post movement to trains, which makes Zero sense to support the initial Argument
Yes, that is the premise. To put it as simply as possible, a diesel generator powering an electric drivetrain can always run in it's peak efficiency band. A Diesel Engine directly moving a vehicle is not. If you had a perfectly flat course, and vehicle a running at constant speeds for extended periods of time at a speed that matches the peak efficiency of the diesel engine, then it would be the better option.
The fact is, hybrid systems are more efficient in real world conditons. We have hybrid cars all over the place, which are more efficient than their gas only counterparts.
The efficiency of a very good and big Diesel generator is ~50%running in its optimal state. You lose about 15%-25% from charging the battery. You already lost a minimum of 65% of energy before the car even rolled, which results in 35% of energy left.
A modern diesel car's efficiency is >40%.
Hybrids are mainly so good because they win brake energy and such back by charging the battery, also because you charge it at the power plant, not a diesel generator. They don't charge the battery with their motor.
Trains are hybrids because there arent Power lines everywhere. They dont use the motor to charge the battery either.
It's more efficient than a gas powered car though, as theyre at about 25% efficiency. Not if you charge the accumulator with Gas though. Physics, I tell ya. You cant win energy by converting it more often.
Edit: When you charge the battery from the power plant, it's efficiency is about 65%.
Yes, that's at least part of the point.
Where do you think they charge from? Answer carefully, I drove a hybrid for the last 10 years, so I know where that energy comes from.
I answered that just one sentence earlier.
Or do you mean when you plug your car into the charging station?
Dont tell me you charged your car for 10 years with a diesel generator because you thought it would be more efficient.
Edit: There's different types of Hybrids by the way. Judging by your replies, I assume you have one that only gets it power from braking energy and heat and going downhill, and doesnt have a plug.
Almost all of them charge via regeneration, so they do charge from the motor. My particular hybrid would also charge from the motor while in neutral (why spin the engine and do nothing with that rotation?) Plug-ins just have the option to top up from another source, but they will still charge from braking.
Your car wouldn't switch off or to electric when idling, since that's even more effective?
So, are you still arguing that charging EVs with diesel generators is more efficient than driving a diesel car?
Only if you are still arguing that...
BEVs create a significant amount of waste heat compared to ICEs. Diesel electric trains and hybrid cars are less efficient than their ICE only counterparts and logistics professionals have been wrong for decades.
Where did I argue that? Are you now putting words into my mouth?
Just admit you were wrong dude, it isnt that hard.
No need to admit anything. Here you are insinuating that my statement about the heat generated by EVs and ICEs is not correct...
That was your primary response to my statement that EVs generate an insignificant amount of heat compared to ICEs.
You also said this...
And the answer, which I gave you is that a diesel generator is not the same thing operating under the same load and conditions as a diesel car.
I also provided 3 real world examples of hybrid systems that outperform their combustion counterparts. I will admit that I was unable to locate specifically a hybrid diesel car, or an electric car with a diesel range extender.
Did you forget that the argument started that EVs that were charged with a diesel generator is more effective than a regular diesel vehicle?
Based on that false claim you argued in favour of hybrids using the false pretense from the start, and that what I discredited by "put a diesel in the trunk", because by your logic that would be more efficient than a diesel.
You even continued to argue in favour until I did the calculation. Even then you tried to weasel your way out by claiming your motor would indirectly charge your battery, which it doesnt.
I was never arguing that winning back lost energy with a secondary electrical system doesnt make sense. But that wasnt what you claimed. You wrongly assumed hybrids were using the motor to charge the battery, which they don't.
Your numbers are not correct. Can you cite sources for them?
Can you clarify this? The motor does both directly and indirectly charge the battery in most (if not all) hybrid cars.
Yep there it is again. Definitely not trusting your armchair understanding of physics and automotive engineering.
Tell you what. Cite one example of a production vehicle where they removed they hybrid system and gained fuel economy, and I'll admit that ICEs alone are much more efficient. Until then, you're wrong, I'm right, and I have 3 real world examples to back it up.
Lol, you just claim my numbers arent correct because?
But you're right, I compared the best stationary diesel engine with 50% efficiency instead of a usual one, and used the low end of efficiency of the diesel car. But that was in your favour.
There you go:
https://www.ourmechanicalcenter.com/archives/12117
https://www.tuev-nord.de/de/privatkunden/verkehr/auto-motorrad-caravan/elektromobilitaet/wirkungsgrad/
https://go-e.com/en/magazine/ev-charging-losses
https://phys.libretexts.org/Bookshelves/College_Physics/College_Physics_1e_(OpenStax)/07%3A_Work_Energy_and_Energy_Resources/7.06%3A_Conservation_of_Energy
Hi, ich hab mir grad den ganzen Thread angeschaut und muss noch schnell meinen senf dazu geben. Generator betriebene Elektrofahrzeuge sind tatsächlich effizienter als direkte Verbrenner im Realbetrieb aufgrund mehrerer Punkte:
P.S. i assumed from previous comments that you're also a German (or at least german speaking) so I kept my comment in german. If I'm wrong and you (or a random reader) want a translation, just comment and I'll do a translation tomorrow.
Edison's series hybrid electric truck gets 21mpg, beating comparable diesel only semi at 6-8mpg.
Took a bit, but there is your real world example.
You also still don't have a real world example of a car that gained efficiency after removing the hybrid system.
We've had those for freight trains for decades now. That is also the model for many hybrid vehicles. They are well proven to be more efficient. Also, they don't need to use the trunk, there's a perfectly good space available where the less efficient engine used to be.
We're talking about charging EVs with diesel generators, which is indeed not as effective as a diesel vehicle.
Even the hybrid trains dont power the electric motor with their diesel Motor. The electric Motor uses excess heat and break energy to get powered.
Freight trains have been using a diesel generator to directly provide energy to electric motors on each wheel for a long time now. The only difference to car hybrids is the train doesn't use a battery in between.
Last I ran the numbers, it seemed like on paper charging off an industrial scale generator was around 20-30% more fuel efficient per km than directly running an ICE car, but I based it on the advertised efficiency values of a random average seeming diesel car, compared to rather pessimistic charging loss and efficiency numbers for the EV. The inefficiency of even modern ICE cars is quite astonishing, even compared to the engine in a generator that can constantly run at the optimal RPM and load for efficiency.
Okay....now that the left is finding every reason to hate on Tesla, allow me to help: this is, and always has been, a massive fucking myth. It never was more energy efficient than a regular ICE vehicle.
Mainly because of its construction. Mining the cobalt, etc for the batteries is very energy intensive. Then there's the tires. AFAIK, you can't just throw any old tires on a Tesla vehicle. You have to buy their special tires with all these sensors in them. I think there are knockoffs, but still. You also have to change the tires more frequently than traditional ICE vehicles, because they wear out faster, because the Teslas are heavier. A car weighs as much as an SUV or truck (3,582 lbs - 4,065 lbs), the Model X Plaid weighs 5390 lbs, and the Cybertruck weighs 6000-7000 lbs.
The damage doesn't stop with the vehicle itself; we must also consider the impact of heavier vehicles on the roads. It will also cause the roads to wear out faster than normal.
Unless it's crashed or burned in protest or whatever, IIRC, a Tesla vehicle can redeem itself from its massive environmental cost to produce & such. But only after many hundreds of thousands of miles on the road, and by the time that occurs, you'll need to replace the battery. "Tesla batteries can last between 300,000 to 500,000 miles, which translates to about 1,500 battery charge cycles." Kiss another $13K - $20K goodbye to swap out that battery for a new one.
So with its far simpler & straightforward construction out of readily available material, coupled with a sprawling existing infrastructure...the ICE car is more eco-friendly and cheaper to operate! And the hybrid vehicles are better than both full-electric & ICE, best of both worlds.
The tire thing is completely made up. Yes, they sell their premium tires but they are not necessary and do not contain electronics. https://www.tesla.com/support/tires
You are arguing a side rather than looking at facts.
You are correct that it is best to have a lightweight car if you have to have one. But an electric one does take over in environmental cost relative quickly and is cheaper in countries that don't subsidize fossil fuels and tax emissions. In addition the air quality in cities improves.
Or you could use literally any form of public transportation and kick the ass of both. ICE or not cars are just a stupid waste of space and resources. They need to be phased out. As a "lefty" I have never advocates for electric cars. They were always a distraction to try to keep car based infrastructure alive.
Not all of us live in cities, nor would we ever want to. I do not have access to public transportation to take me to & from one of my jobs.
If you are able, yes, kind of amazing perks & I'd use it. It would certainly save me more than a little money in car insurance, maintenance, fuel, potential for accidents, etc. But it is not a feasible option, specifically for me.
I lived in a small town in the Netherlands for 3 months last year for work. Never once needed a car. You're imagining a world where youre not using a car in a world built for cars. Do they have their use. Sure. But the scale at which we use them and the world that we build around their use needs to be done away with.