Tesla Drivetrain Engineer Explains Why Electric Motors Are Inherently Superior To Gas Engines

DEC 17 2015 BY MARK KANE 114

Tesla Model S

Tesla Model S

Fortune interviewed Dustin Grace, who for nine years was working on drivetrains at Tesla Motors, and earlier this year switched to electric bus maker Proterra by becoming their director of battery engineering.

Grace shared his opinion about the advantages of electric motors over internal combustion engines.

We listed some of the main topics, but full details can be found directly in the source Fortune article linked further below:

  • Electric motors generate motion, not heat (high efficiency)
  • They’re more powerful (high torque from zero rpm for great acceleration)
  • They’re simpler (not many parts, no transmission needed in most cases)
  • They’re (vastly) easier to service (less parts, smaller and lighter, fewer subsystems around the motor)
  • They feed themselves (regenerative braking capability)
  • They’re smarter (ultimate controlling accuracy, especially useful in AWD with two or even four motors controlled independently)

Source: Fortune via ecomento

Categories: General, Tesla


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114 Comments on "Tesla Drivetrain Engineer Explains Why Electric Motors Are Inherently Superior To Gas Engines"

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The grid fossil fuel to electricity is about 40% efficient, by the time you transmit it, convert it, put it in and out of a battery, through a controller and motor you would get about 30% fuel to motion.

That’s why god invented the sun 😀

40% sounds made-up. Cite your sources please.

Let’s also not forget that “fuel to motion” efficiency for a gasoline car (where the fuel is crude oil) must include all the energy required to extract, transport (usually thousands of miles!), process, and transport (again!) the refined gasoline to your local gas station.

The “fuel to motion” efficiency for an electric car still comes out on top, by far.

Yep, combined cycle natural gas plants are sixty percent efficient.

Burning gasoline in a modern power plant, and using that to charge an EV would be much more efficient then using an internal combustion engine.

U.S. does not have 100% combined cycle, just look up grid efficiency.

“In a traditional coal plant, for example,
only about 30-35% of the energy in the coal ends up as electricity”

Grid efficiency, which is better in AC than DC (thanks, Nikolai Tesla!), is well-understood. This is yet another argument for abandoning the grid. The problem, however, is that not everyone has a rooftop of their own and a garage; those folks, however, do have access to charging stations, which I see with solar panels powering them more and more. Electric efficiency, even with the facts of grid power, just isn’t debatable versus combustion.

Yes, and at one time the majority of our US population had no access to telephones. Just one of a huge group of possible examples that show that “what is today is not what can be tomorrow”.

And whoops, I have solar on my house so roughly 88% of the PHEV is free electricity from my roof. My over production goes free to the city as a credit to me and to cover my fee to charge at ~150 city EV stations.

Imagine more people did this and we reduce coal plants (most polluting). Key is energy storage of the solar production at night.

Coal is big part of USA grid. However so id nuclear, natural gas, solar, wind, hydro.

One can not simple take lowest number and use it for it all!

At lest get average for each and multiply it by “market share” in grid.

SJC said:

“In a traditional coal plant, for example,
only about 30-35% of the energy in the coal ends up as electricity”

And therefore, it’s good that in the USA, the percentage of grid power provided by old coal-fired plants is rapidly dropping year-on-year, as the old plants are being replaced with more modern combined-cycle natural gas fired plants.

It’s even better that the amount of grid power provided by renewable energy is going up, while the portion from dirty coal energy is going down.

Those were your points, right?

Oh, wait… no, you were trying to post yet more EV-bashing FUD.


“The National Energy Technology Laboratory (NETL) took APWG’s analysis a step further,
finding that while the average efficiency of U.S. plants was 32% in 2007, the efficiency of the top 10% was five points higher at 37.4%.”

You are brilliantly demonstrating the waste and inefficiency of fossil fuels.

That is the point, most EVs are charged by fossil fuels.

But you don’t have to. Switching to EVs makes it that much easier to get off fossil fuels. It also allows you to use the existing fuels more efficiently.

Yes, but because they are five times more efficient than Infernal pollution engines, you still pollute less with an EV.

My EV is powered by the wind. Many others are powered by the sun.

Even if powered by fossil fuels, I’m STILL more efficient than gas-powered cars.

Yeah, but wait till you have to replace the batteries.

Majority of EVs in Canada are powered by renewables (or at least low GHG sources) – look up the power supply mix of BC, Ontario and Quebec (where vast majority of EVs are right now). 2 out of the 3 provinces are almost entirely hydro and have several million residents. It is a reality here already, and will soon be the reality everywhere 🙂

It’s great when electric grids go renewable, but not required for EVs to make a difference in fuel consumption and pollutant emission. My Tesla uses ⅓ of the energy of my Prius—and I imagine ¼ of the energy of a gas-only car of the same size. Even if we burn fossil fuels for electricity, we are better off driving electric.

SJC said:

“That is the point, most EVs are charged by fossil fuels.”

The best liars are the ones who mix a bit of truth in with their lies… just like this one.

Almost no EVs are charged only by fossil fuels. Even in the States with the “dirtiest” grid power, some comes from “clean” sources such as hydro, nuclear, wind, and geothermal.

And in some States, most notably those in which most EVs are sold, the percentage of “clean” energy is very high.

But of course, those “inconvenient truths” don’t fit your EV-hating FUD, do they?


Yep. That’s why solar and EVs are such a good pairing. Not so much about efficiency, all about the Total Cost of Ownership.

$2,000 worth of panels on your roof gives you 30 years worth of fuel. That’s pretty hard to beat.

Right now today, the best way is with Net Metering + Time of Use. After that gets phased out in a few years, stationary batteries like the Telsa Powerwall will enable you to drive on sunshine even if you’re not home when the sun shines.

Current net metering subscribers get grandfathered for 20-30 years. (That deal will be good for at least a few more years in most places that offer it).

Very few people charge their EVs with solar panels. 40% of the grid is coal fired power plants with more than 70% fossil fuel fired. When people say their EVs are clean and efficient, they make believe there is no power plant at the other end of the charge cord.

You get the PUPU – Lensmen award for accuracy.

I and many others here charge their ev’s when the sun is shining on their solar panels. Hardly ‘very few’.

Also, Plenty of new plants going in world wide are combined cycle. Otherwise Mitsubishi amoung others wouldn’t be selling so many HRSG’s. (Heat recovery steam generators).

Those plants co-located with District Heating world-wide are also extremely efficient, more so in the wintertime, but then the most modern plants can be optimized on a seasonal basis, i.e. make more electricity during the summer time and more district steam during the winter. Modern two-stage adsorption heat pumps also makes use of whatever steam is made during the summertime, as well as domestic hot water.

Let’s say there are one million EVs in the world, tell me what percentage are charged with solar panels. I would say less than 1% constitutes very few.

Ignoring the fact that a very high % of EV drivers also have solar panels, lets take an “unimportant” country like Germany (that just happens to be the LARGEST ECONOMY in the Eurozone).

THey get 6.5% of their juice from solar.
They get 10% of their juice from wind.
They get 10% of their juice from biomass.

SO if ev drivers in that country DO NO SOLAR they still are charging 6.5% WITH SOLAR POWER WITHOUT EVEN KNOWING IT.

EVs on the U.S. roads account for .1% of the vehicles after 5 years. If we want to reduce imported oil that percentage will have to rise fast. I don’t see that happening.

Generally speaking, we don’t import from the middle east any longer.

The current problem with oil is that it is so cheap you almost can’t give it away, and the price seems to be headed further down.

My Nephew is currently taking a long trip in my volt, and the price of charging is just a bit cheaper than an equivalent amount of gasoline.

Whereas before it was about 1/2 the cost to ‘refuel’ using electricity.

Too bad few will consider electric cars until the price of gasoline goes back up again.

Sven tells us in NYC it is actually CHEAPER to use the engine than to plug it in, since he has to pay ridiculous confiscatory rates of on average $0.31 1/2 per kwh.

Actually being in the solar industry I get a lot of market information and from what I have read about 40% of EV owners have solar.

Hey, I don’t know how, but I got marketing material for a Solar Garden, and I’m pretty sure that I’m going with it, because my roof is covered to 70% with dense foliage half the year. It’s a regular discussion topic in the local EV clubs in town, and the solar garden I’m buying into is being built by the same installer who actually did the rooftop installations by some friends in the EV club (serendipity, not referral), and he knew their names. There’s a common mindset at work here.

Having a few solar panels does not power your house nor two cars. Most of the energy to charge EVs comes from fossil fueled power plants.

That’s just more nonsense.

I have 38 panels on my home, seeing as my locale gets as much Sunshine as Alaska.

Even so, in the time my 2 EV’s have used 9,000 kwh of electricity, I’ve made 15,200 kwh during the identical time from my solar panels. So “a few panels will run 2 cars”

Fantastic to see how no specific people in this discussion on the subject. If the guy claims having 38 solar panels ( 1 watt or 100w each ??) , but not providing total power or output- we could find nothing from this info. If he provide output 15,000 kwh ( month, year, decade ??) , but not specific period of time, we know even less if he is lying or not.


SJC said:

“Let’s say there are one million EVs in the world, tell me what percentage are charged with solar panels. I would say less than 1% constitutes very few.”

More lies. InsideEVs editor Jay Cole recently posted it’s 10%. Older sources say as much as 30%.

Dude, how much is Big Oil paying you to post EV-hating FUD?

Bill Howland said:

“You get the PUPU – Lensmen award for accuracy.”

Wow! Maybe we should create a “Bill Howland” award for being, as they say, “not even wrong”.

And I don’t appreciate you trying to put me in the same pigeonhole group with an EV-hating, FUD-spewing troll, Bill.

Two things:

1). I don’t know what a FUD is. Please use the king’s engish.

2). Don’t worry, you’re not being pigeon-holed as you are in a Class by Yourself.

For us in Quebec. Canada it’s 99% hydro and wind electric power .

“When people say their EVs are clean and efficient, they make believe there is no power plant at the other end of the charge cord.”

Let’s not try to distract the argument by composing strawmans.

People say their EVs are clean and efficient because they are:

There are a bunch of different emissions calculators where this can be figured:

Cleaner Cars from Cradle to Grave (2015)

Over their lifetime, battery electric vehicles produce far less global warming pollution than their gasoline counterparts—and they’re getting cleaner.


Your numbers are pretty far off, ~20% nuclear and ~13% renewables. That’s a third of the grid that’s emission free.

So? Wind farms are the fastest growing segment of electricity production today. Coal, by comparison, has basically not produced a new powerplant in the US in 5 years.

So that means that all of the growth in America’s power production in recent years has been powered by wind. We’re now working on replacing old powerplants with wind and solar as well.

And all this only assumes you live in a place with a particularly dirty grid. Not everyone has this problem. (see also http://images.thecarconnection.com/med/electric-car-wells-to-wheels-carbon-emission-equivalencies-in-mpg-union-of-concerned-scientists_100440262_m.jpg)

What does this have to do with the motors?

To compare with oil you need to treat all non-fossil fuel sources as 100% efficient. That makes the average efficiency 60%.

Have you been listening to Davemart? This sounds like his favorite argument.

Thanks for pointing that out.

The fallacy there isn’t as obvious as SJC’s other fallacies. When a EV-hating FUDster posts “Grid power is X% efficient”, it’s not obvious that he’s using the word “efficient” in a way that has a different meaning than “efficient” as in the fuel efficiency of a gasoline engine. It’s actually a subtle form of the fallacy of Equivocation.

The “efficiency” of a hydroelectric power plant, or a nuclear power plant, or any type of renewable energy source, is 100% if you’re comparing how much fossil fuel they waste when producing the energy. Of course, you won’t find those energy sources listed as “100% efficient” in U.S. Government sources, because that’s not how they’re measuring efficiency.

In addition to all the other comments poo-pooing your POV on this, I’ll add mine.

1/ You (to be fair, like most ICE-huggers) appear to be blissfully ignorant of how much electricity is actually used to make petrol (and diesel). It difficult to pin down an actual number as lots of other stuff is obtained at the same time in the refining process but some estimates put it at as much as 6kWh. To put that into context, 6kWh will take an average EV (car) about 20 miles.

2/ If you implemented a renewably-based electricity generating system combined with a suitable storage system (such as Tesla’s Powerwall) you could quite easily eliminate half the existing generating capacity of whatever country you happen to find yourself in. Virtually no transmission losses there. This is what is keeping the world’s utility company bosses awake at night. Thing is, you can do it whether they like it or not. The government won’t whinge either because you are directly helping their CO2 reduction plans.

Anyone who thinks EVs are all ‘dirtier’ than ICEVs is either a complete moron or deliberately trying to deceive you. MW

Yeah, I’ve heard figured from 4.5kWh/gallon to 6kWh/gallon. The running average in my LEAF is 4.5 miles/kWh. That 6kWh of power used to refine that one gallon of gas will power my car for 27 miles.

Additionally, it’s much better/cleaner/easier to remove pollution from one location (the power plant) than to do it from multiple locations (exhaust pipes).

SJC is right, though, in that it will take some time to get over 0.1% of vehicles being EVs. As batteries get cheaper and fuel (eventually) gets more expensive (what are the Saudis doing?!), EVs will become more prevalent.

We, as EV drivers, need to spread the love. Get your co-workers and friends to drive your EV. Talk about the benefits (pre-heated/cooled car; smooth driving; quiet; low maintenance; inexpensive per mile) and at least they will be able to make a better decision about EVs than a typical dealership will do.

These numbers don’t make sense. 6 kwh would cost a homeowner $1.89 in NYC which is a bit strange since the Indian Reservation near me is selling 87 OCTANE for $1.75 a gallon and is making a profit. IN fact, American Industry, including oil refineries, are recovering more and more energy from their operations and flaring low-btu gasses (that used to be uneconomic to recover) less and less because methods are being developed to recover the resource. People bandy around the word efficient when they mean, I THINK, efficacious. But then I don’t understand the arguments here anyway, and that is perhaps why even some rare commenters on this blog say they have been scared away by some of the technically-challenged proseletizers here. Its interesting that AL Gore’s mentor Maurice Strong who recently died led a charmed life for a 14 year old secondary school dropout, who ended up working for the Rockefellers, and eventually became head of Canadian Dome Petroleum while still quite young. George “Save the Planet” Soros just becaame the world’s largest owner of Coal. So do as I say, not as I do. No wonder a minority of us in my area of the country believe… Read more »

I think these points need to be continually emphasized. I think part of the problem is that most car makers are conflicted to some degree when it comes to bevs. In other words If I were the head of an ev company and did advertise, I would bleat those points home adnauseam.

I would have on where sheep were stomping their hooves in time and bleating out evs goooood… ices baaaaad.

+ 1


lol, best laugh so far this month.

I just read the article and this was at the end:
“For a look at Toyota’s Mirai fuel-cell vehicle—a possible contender for Tesla’s Model S— watch this Fortune video:”

That was good for a laugh.

The title probably should have read Former Tesla Drivetrain Engineer. I was shocked that anyone other than JT was allowed to comment, until I read “former”.

That we knew for the last 150 years, thanks for reminding us anyway. Problem are the batteries. That we also know for the last 150 years…

Edison’s Nickel-iron batteries provided more than 100 miles range to luxury cars around 1908, recharged in 5 hours and were advertised with a life of 30-50 years.

We may ask “Who killed the batteries” 100 years ago!

You left out that part on the 1908 EV where the top speed was 20 mph.

Today’s batteries allow EVs to travel at modern speeds with similar or better range. That requires much higher densities than early 20th century batteries provided.

Unfortunately, the battery technology on early 1900s EVs didn’t improve quickly enough to keep up with ICE vehicles and the ICE eventually took over.

You left out 100 years of aborted evolution for the batteries, closely watched by big and bigger and bigger oil.


Not sure what you are talking about as there are some good batteries available.
For instance I own 50 yr old flooded NiCad batteries that still put out rated power.
What they, lead batteries needed was lighter, more aero EV’s to put them in.
It isn’t hard to get 100 mile range from lead batteries if you design it for
I’ve been driving EV’s for 22 yrs now mostly lead at a fraction of a gas version’s
Though I’ve recently bought a used Volt battery pack for my next EV now the price is down and quality up enough to make it worth switching from lead.

You can’t pull 2000amps out of an 85kWh iron edison battery… too much internal resistance.

It’s not a question of technology, electrics were always superior to ICEs
It’s a question of commercial plots from the first billionaire not wanting to lose again a big potential market: cars. He just lost the one, the huge one having made his colossal wealth possible: domestic lighting.
His own kerosene lamps replaced whale oil lamps, but electric bulbs were catching like wild fire so he made an agreement with it’s early partner Henry Ford to massively build cheap cars. At the express condition that they had to run on petroleum.
Of course, this part is not written in history books.

Might be all true.
But the thing I would love to read in your one liner comment, is how much kWh those wonderful Edison Nickel iron battery stored and what was their weight and volume.
The C rate would also be helpful.

In short, where is the specs of those marvel?

After that we can discuss if they were so awesome.

I don’t think they were.

The modern versions are not so different. Google a little…
The point is that electric cars of more than a hundred years ago were quite good performers for the time, better than ICE.
Edison patented two versions and had a deal with Ford for 150 000 electric cars /year in 1914. A fire burned 100,000 batteries in december of that year. hummm..

There were more than a hundred electric car makers in the early 20th century.

Here is a comparison of Lead Acid vs Ni-Fe

“1910: Four Models from $2,000-$2,600. The voltage was increased from 48 to 56. Baker claims sales of 1,000 cars. On August 30 1910 they ran a car for 201.6 miles on a single charge with a lead battery, later in the year they achieve 244-1/2 miles with an Edison battery. It is likely that at the end of the run the lead battery was scrap and the Edison battery was nearly normal.”


If you want to compare kWh for kWh modern lithium-ion of your Leaf with the tiny needs of running a horseless carriage of 110 years ago, it would be unfair.

What is good to know is that marketing from 100 years ago was as deceptive as the modern version, associating electrics with women, and giving the awful crank start and the noise a viril aura.

The Model T was such a tremendous success that as early as 1907, electrics were sporting a faux radiator!

“Of course, this part is not written in history books”

Yeah, unfounded conspiracy theories rarely are

Rockefeller funded Ford all the way to win the Selden patent appeal. I read and know a lot about early oil and car history. Books are not a source of unfounded stuff.

You should know that History is always (re)written by the winners.

So… your argument is that Thomas Edison conspired with Henry Ford to rewrite the laws of physics so that gasoline has a much higher energy density than batteries, so that gasmobiles could have a significantly higher speed than early 20th century electric cars.

And Thomas Edison wanted to do this because he had no interest in selling either electricity (from the Edison Electric Light Co.) or batteries (like the Edison Battery, which he specifically designed to power electric cars of the era).

Got it.


Conspiracy theories are fun… so long as you don’t take them seriously!

Ha! The nasty word! “conspiracy” … But not at all, “business as usual” type of all capitalist corporations every day routine.
You know, when a tiger wants to find food for his children , or a football team compete for winning a game, they all use conspiracies, all the time, all of nature does, it is in our genes, deeply encrusted for thousands of generations, it’s called survival. Schemes and plots and cartels are as old as the world is…

You have to be naive to ignore that conpiracies are everywhere. Even you, when you were young and accused your little brother for the cookies you ate.

Batteries died when a technology arrived that could fuel more quickly and offer more range. That may well play out again a second time.

Those won’t be the issues that matter because the status quo can ALREADY refuel quicker and have more range. As long as batteries have “good enough” recharging speeds and range, that is not a concern.

Right now what matters the most is cost (both up front and the cost to operate).

And this is probably one of the guys who were responsible for not putting enough lube in the early drive units…

“Electric motors generate motion, not heat”

That’s simpler than I’ve ever read it, whether summarized by Mr. Kane, or Mr. Grace.

For all the advantages of electric motor, what’s not discussed is cost. In theory, it should be much cheaper than ICE, especially inductions motors (no rare earth). But in practice, electric motors are more expensive, which is frustrating. Hopefully things will change with scale in the future.

But what is the practical bottom price for electric drive train with mass scale manufacturing? For the controller / semiconductor, I can see ~ $1/kW with mass scale, but I can’t gauge what motor might cost.

Battery is whole other issue, but we know the rough bottom at $100/kWh for Lithium, and hopefully cheaper solutions will come in time.

I’m not so sure about your math or English.

What specific math/english? Try pricing 100kW electric motor vs 100kW (130HP) gas engine.

I’m sorry but you *are* joking aren’t you?

The typical EV AC motor has just *1* moving part (ignoring the bearings) compared to the 100s of highly engineered moving parts in an equivalent ICE. Even Tesla’s motors consist of only about 50kg of copper and aluminium with a relatively simple assembly process. I doubt their motors (~400HP, BTW) cost Tesla more than $1k each, $2k max. Compared to the equivalent V8, you talking 3 or 4 times the price. Further more, in 10 years when the number of AC EV motors being made annually has gone up 100-fold, I would expect the cost of EV motors to have at least halved. ICEV engines are only going to get more expensive as they’ll have to comply with more and more anti-polution regs.

And that’s just the engine/motor, the typical EV gearbox has only a very few, extremely basic, non-bearing components compared with the typical modern auto transmission with its dual clutches, 6 or more gears (+ reverse, achieved electronically in an EV) and torque converter, etc, etc.

Clearly you have absolutely no idea – like most people! MW

Even WITH the economies of scale, a 1.6 liter Honda Civic SI rebuilt motor is going for $2500 on eBay.

Traction motors from LEAFs are going for around $1000 on eBay.

Your argument has no merit, SparkEV.

To add to that, a NEW Leaf traction motor retails for $2400. A new engine for a Versa is $5340. The ICE does not come with an intake or exhaust.

You can compare outrageous dealer pricing, but you wouldn’t pay $5K for versa engine; car is only $12K. Quick google search for “nissan versa engine cost” shows $1.2K. Used Versa engine turns up anywhere from $500 to $1.2K.

Searching for Leaf, pricing for used Leaf motor is $700 to $1.5K.

So despite having hundreds of extra parts in ICE, it’s cheaper to buy today if you had to get one yourself. Why? Only reason I can think of is economy of scale.

SparkEV said:

“But in practice, electric motors are more expensive, which is frustrating. Hopefully things will change with scale in the future.”

You’re claiming that the electric motors which power modern EVs are actually more expensive to manufacture than the gasoline engines which power modern cars?

I doubt that. Even if it’s true, EV motors are certainly not more expensive than the ICEngine plus transmission plus radiator (and water pump and fan) plus exhaust system (including muffler and catalytic converter).

The problem with using an ICEngine to power an automobile isn’t merely that it has about 300-400 moving parts vs. the electric motor’s one moving part, nor merely that it’s horribly inefficient. Another serious problem is all the Rube Goldberg kludges that the poor, inefficient ICEngine needs to be able to power the car without melting or tearing itself to pieces or poisoning its passengers with noxious fumes or violating local noise ordinances.

Rube Goldberg kluges which the much more efficient electric motor doesn’t need.

What I’m claiming is EV electric motor is more expensive than equivalent gas engine at retail level today. As you correctly point out, it should be much cheaper to produce EV electric motor. But gas engine is cheaper, which I suspect is due to economy of scale.

He should better get to work, after reading tesla boards i must assume that a a cheap chinese gas engine will be more reliable than a Tesla drive unit.

If you think the words “cheap Chinese” and “reliable” belong in the same sentence, then you don’t know much about the pervasive problem with quality control, and even outright counterfeiting of parts, in Chinese manufacturing. Especially counterfeiting of electronic parts… and you’d find it hard to make EVs without those!

When the Better Battery is readily available at an attractive price, BEVs will sell well. Car physics makes little difference to the family guy just looking for a suitable transportation appliance at an affordable price. The initial and ongoing costs are the things.

Duh, we all knew that.

That is comparison in component. The problem is the system and infrastructure.

Electric motor is wonderful, anyone who argue against it just doesn’t know enough. But the problem has always been the storage of electricity which is NEVER compact.

ICE isn’t elegant at all. It is terrible. But it converts a chemical fuel which is very compact and powerful, thus dangerous. But that is the system advantage.

Not to mention the last 100 years of “refinement” in infrastructure for gas cars.

EV will get there. But it will take time. Better than never.

I agree with almost all of it. The simplicity and scalability are the most appealing aspects to me. However, the first one however is patently false: “Electric motors generate motion, not heat (high efficiency)” They have highest efficiency down low and produces almost no heat at that low RPM, but EVERY SINGLE AC and DC motor looses efficiency as RPMs climb and thus generates more and more heat. If not, you’d have a perpetual motion machine. That’s why the Tesla’s torque output plummets like a rock (and thus HP flattens) midway through the RPMs. It’s why having a selection of gears is still beneficial and actually improves efficiency over a range of speeds, as opposed to selecting one single fixed reduction gear, which always involves a compromise. And yes, the Tesla still uses a transmission, just a single speed one at 9.81:1 reduction for the P85. That begs the question, why not 10:1? Why not 8:1? Obviously there are tradeoffs with sticking to one ratio because of the characteristics of all motors. Even Zero implicitly recognizes this despite touting a single speed or “no tranny”. That’s why they offer what is essentially a human transmission — the rider can manually… Read more »

“Electric motors generate torque, …. not heat”.

I think I see why this guy went from murmuring drives to batteries at a different company.

ICE’s use heat, and the end result is heat removal by doing work, not heat generation. But no one here cares about that.

People seem to understand here about Hydrogen not being a primary fuel source, but no one wants to discuss prime movers, which is the analogous point with ev’s.

My Solar system on my roof is roughly 14% efficient, and after going through the inverters and wiring, is around 13.5 % efficient overall by the time it hits the charging point at my car. Overall, I’m very satisfied with this efficiency, since my overall expenses are LOW.

NP I hear what you are saying, but anyone who drives a GEN 1 volt or ELR knows at LOW-SPEED, (under 15 mph) the efficiency is very low…..

You have to accelerate V E R Y S L O W L Y to get ok efficiency… It could use another gear. But once you hit 20 mph or so, the efficiency starts getting high.

Why? Since on an AC motor the volts/frequency ratio limit must not be exceeded, very low speeds and voltages make the resistance loss a higher percentage of the losses, including the current losses in the motor stator, and inverter, and in Tesla’s, in the rotor bars.

Electric motors (induction) do not have their highest efficiency at low RPM. Synchronous Permanent magnet is another story, but not the tech Telsa uses (rare earth metals). Typically the highest efficiency is at rated RPM. Torque drops as RPMs increase is just a fact of life on electric motors, it is irrelevant to losses.

I believe, rather than a classic transmission, we will realize that effect from dual motors as time goes by – i.e., rather than pursuing the diminishing return of 0-60 times we’ll see the ‘front’ motor minimized and optimized to be at peak efficiency for 50-70 mph travel, and the ‘back’ motor will only engage for slowing, once the ‘computer’ has determined that we plan to highway cruise – kinda’ like the lock-up torque converter of old.
Still AWD benefits, but the ‘front’ motor is designed with highway as its primary purpose.

“They have highest efficiency down low and produces almost no heat at that low RPM, but EVERY SINGLE AC and DC motor looses efficiency as RPMs climb and thus generates more and more heat.” You obviously haven’t run electric motors much if your truly believe that statement. The efficiency band of electric motors is affected by many parameters and rarely are they most efficient at low RPMs. I had to put a smaller drive gear/pulley on the motor of my Gizmo EV because the RPM was too low and the motor would over heat due to the higher currents needed compared to the higher RPM gearing. For a series DC motor check out this graph: http://www.go-ev.com/images/003_09_01_WarP_9_Graph.jpg Note that the efficiency is low at the start of the curve and goes up initially. What about this small PM motor: http://www.groschopp.com/wp-content/uploads/PM-speed-torque-efficiency-curve1.jpg Again the efficiency is low at low RPM. Even better is this motor/inverter chart: http://www.techno-fandom.org/~hobbit/cars/ornl-motor-efficiency.gif Note that the highest efficiency is in the 2000-3000 RPM range. The reason the torque plummets as RPM goes to extreme values is not due to the efficiency dropping. It has more to do with the back emf as the RPM increases and is a function… Read more »

In Teslas, Power factor decreases, thereby increasing all resistance type losses, and also windage, gearing and bearing losses increase at screamer speeds.

Its of no surprise to me this dude ain’t working on motors any longer.

You can have a slow 3600 RPM, 2-pole, 60 Hertz AC motor that will weigh 10’s of thousands of pounds to produce 400 HP or you can have a 400 Hertz, 4-pole AC induction motor that will scream at 12,000 RPM, but weigh a few hundred pounds. In other words, the only way to get good power/weight ratio is to go with high frequency design AC motors. Higher frequency also means higher RPM’s. Not really easy to get away from this. There is always trade offs involved.

In this case, their poorly chosen trade-offs seem to be more in the gearbox that has in many cases difficulty to accept what the motor is doing to it.

I know they, during warranty work, usually swap the units out en masse, but I’m under the impression its due more to wear nearer to the gearbox as opposed to the motor or inverter.

Cool chart. My Leaf is very smooth, so I don’t notice anything about the efficiency of the motor. On my electric cargo bike with mid-mount motor chain drive however, I do get some subtle cues (vibration, sound, heat) as to the efficiency of the motor – it struggles from starting in a high gear (ie needing high torque/low RPMs). There is an RPM range that the motor just seems “happy” to be within, so I change gears on the bike to accommodate that range as I change speed (or load, ie hills, weight). http://kootenayevfamily.ca/say-hello-to-our-electric-edgy/

np said: “Electric motors… have highest efficiency down low and produces almost no heat at that low RPM, but EVERY SINGLE AC and DC motor looses efficiency as RPMs climb and thus generates more and more heat.” Within the speeds and torques at which a properly engineered EV’s motor is engineered to run, there are only a few percentage points of difference between most efficient and least efficient. The least efficient is still about three times as efficient as the highest efficiency of the actual performance in gasoline/diesel when being used to power automobiles*. On the graph linked below, the efficiency ranges in the vast majority of possible EV motor speed/torque combinations ranges from a high of 93% to a low of about 85%: http://www.teslamotorsclub.com/attachment.php?attachmentid=96558&d=1443881538 np, I think you’re confusing the power and torque curves with efficiency. See here, but note these are not energy efficiency curves: http://www.teslamotorsclub.com/attachment.php?attachmentid=23100&d=1370283832 np said: “If not, you’d have a perpetual motion machine.” False. An electric motor doesn’t put out more useful work than energy input into it. Nobody is claiming an electric motor is more than 100% efficient. np also said: “However, the first one however is patently false: ‘Electric motors generate motion, not… Read more »

More pedantic blather from wikipedia.

If electric motors are so much more ‘efficient’, and have such obvious advantages, why are gasoline powered cars cheaper, and some, under some circumstances, get better gas mileage?

Maybe I shouldn’t ask the question since I’m sure the answer will be more drivel, but let me put it plainly.

People understand that Hydrogen is not a ‘Primary Fuel Source’ and therefore efficiency comparisons are pretty meaningless.

Electric motors are also not prime movers, and therefore all these articles on InsideEvs which make efficiency comparisons, excuse me, are pretty-wrong-headed.

It would be somewhat more compelling for me to listen to you drone on if you would simply purchase a used low-cost EV (spend under $10,000) since then you’d have some skin in the game.

But as they say, free unrequested advice is worth the price – nothing.

You constantly call me an idiot ( who just happens to own 2 ev’s and is on his 3rd).

lighter, smaller, and ultimately cheaper too

Let me know when the Tesla’s battery energy density bumps up from 0.16 MJ/kg to petrol’s 45MJ/kg

It doesn’t have to. Since electric motors are over 3 times more efficient than gas engines, to come up with the same power/weight that you’re quoting, they only have to get to 15MJ/kg or less.

assuming a current max density of 0.5MJ/kg and an annual improvement of 20% still makes that 18.65 years off

If you’re anti-BEV..don’t complain or blame the government for inaction when air pollution in your community becomes dangerous to your health. When air pollution becomes dangerous in your community I want you to go for a run and enjoy the toxins that will be contaminating your lungs…with a big smile on your face.

Batteries don’t have to get to 45MJ/kg to be competitive and besides as the article pointed out there are pros to the electric motor compared to the ICE.

Energy density of the fuel is no the be and end all, though granted it is important and most BEV aren’t quite there yet, but it’s coming.

timblanchant said:

“Let me know when the Tesla’s battery energy density bumps up from 0.16 MJ/kg to petrol’s 45MJ/kg”

Let me know when the typical gasmobile’s engine, transmission, exhaust system, radiator, oil pump, fuel pump, and all the other Rube Goldberg kludges it needs to make the poor inefficient gas motor power the automobile… let me know when all that gets down to the size and weight of the EV’s motor, inverter, and PEM.

Yes, no-one would choose an ICE as a way to propel a vehicle. The only reason that ICE is used is because of the incredible energy density and easy of handling of petrol and diesel, that’s it.

Energy density and a distribution network are compelling qualities, but we don’t have to have internal combustion with particulates, NOX and smog.
Reform liquid hydrocarbons on the car to hydrogen for a fuel cell in an FCEV. Plenty of batteries for around town and plenty of range for trips.

Could have just said “Because an electric motor, unlike an internal combustion engine, isn’t a heat engine, and isn’t limited by the maximum efficiency, also called Carnot efficiency, of heat engines.”

But I suppose that would have sailed right over the heads of many or most in the intended audience.

Great engineering data … explains why elevator cars are all-electric and not ICE powered!

Think about it … what would the travel experience be like if elevators ran on ICE?

I will not rule out ICE in use for many years to come. 20 years ago ceramic ICE were demonstrated very effectively getting well over 50% using Diesel method of combustion. youre not seeing them yet because of the expense and relative fragile nature of them. I’m not saying electric isn’t bad, it has the best power to weight ratio in general, but batteries will always be a problem until things like ultra capacitors made from graphenes comes into practice. then again hydrogen storage using hydride technologies again using graphenes in combination of using graphene fuel cells will be the norm. very disruptive technologies these graphenes pose now. be prepared to see this stuff in everything from creating extremely strong plastics to ultra low resistant conductors to creating very efficient fuel cells. as far as motor efficiencies again these graphene conductors have already seen a 10 fold decrease in resistance – almost no eddy losses associated with metal conductors(this will help extend the high frequency usage and maybe eliminate filtering capacitors) funny enough though when looking at inverter technologies used for controlling servo motors their efficiencies are not nearly as good as their analog counterparts. Here they are designed to… Read more »

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