Engineering Professor Answers Electric Car Questions

I'm Willett Kempton,

professor of Electrical and Computer Engineering

at the University of Delaware.

I'm here today to answer your questions from the internet.

This is Electric Vehicle Support.

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RHAmembers asks,

EVs explained: How do electric cars actually work?

I'm gonna use this diagram to explain.

A gasoline car uses a fuel pump and gasoline pushed in.

Instead for an EV,

that blue cable that you see is a charging cable.

You plug the car in and electricity flows into the battery.

So instead of a fuel tank, you've got a battery.

That big yellow thing is a really large battery.

It's more or less the same as a battery

in your cell phone or laptop computer.

It's maybe using lithium ion.

That's a traditional type,

and you can store kilowatt hours of electricity.

Then when you drive, you unplug, of course.

And now the electric energy,

the kilowatt hours that's in that battery

is flowing out through a motor drive,

the blue thing of the diagram.

So that's turning the battery power into electric energy

that's ready to run a motor.

pettyrepair954 asks,

Why do electric cars accelerate faster

than most gas-powered cars,

even though they have less horsepower?

Average electric car

might have less horsepower than a gasoline car.

It'll still accelerate much faster.

The torque of an electric motor is 100%

from starting all the way to full speed.

Torque is the turning power.

If you're turning a crank and pushing harder,

that's more torque.

If you're pedaling a bicycle uphill,

you have to push harder on the pedals.

That's more torque.

On a gasoline motor, you get maximum torque

only when you're at almost the maximum RPM.

So that's why you have gear shifts and all this.

The way you run at a gasoline car,

it's [imitates acceleration sounds].

You know, you're shifting

and moving to higher and higher gears.

That's because you're only getting maximum torque

at nearly the full RPM.

So you don't have any of that nonsense

with an electric motor.

So Random-Nerd827 asks,

How environmentally friendly are electric cars actually?

You consider two things in environmental friendliness.

One of the mining materials, manufacturing,

all that that goes into making the car.

And then what about the fuel consumption

and pollution from fuel consumption?

If you're using electricity,

there are probably some emissions

in creating that electricity.

When you drive your new electric car off the lot,

it's less environmentally friendly than a gasoline car

that you would've bought new and driven off the lot.

There's more materials, more weight,

and some of those materials have environmental impacts.

So actually the embodied environmental cost

of the car is a bit higher.

Not a huge amount,

but maybe 30% higher, something like that.

If you are using gasoline or diesel,

obviously you've got emissions right out of the vehicle.

That is so much dirtier,

that over the time of driving the car,

it may be as soon as two years after you've bought it,

you're already ahead.

And over the life of a car,

typical car in the US lasts 12 years or so,

you're much more environmentally friendly.

Okay, morecowbell520 asks,

Will we see 600 mile range EVs standard

in the next 10 years?

We have an announcement from Toyota

that they will have a 900 mile Toyota in 2027.

That's what, two years, not 10 years.

But you said standard.

Do we want a 600 mile standard for EVs?

I would say no on that.

Maybe you need 600 miles or 900 miles

or 1500 is certainly possible

with batteries that we see now coming.

But do you really want that?

Because that's gonna be more than weight.

For most people, 300 miles is really a reasonable range,

and that's what most EVs sold in the US are today.

You can buy a 500 mile range EV in the US today.

Gonna cost you maybe 80 grand or 100 grand.

Or would you rather have a lighter car,

probably get a little bit better mileage,

pay less for the car and get say 300, 350 miles range?

That_Cool_Guy, What is maintenance like on an EV?

EV maintenance is way less

than maintenance of a gasoline car.

Mostly it's going to the dealer,

and they check some things and do software updates,

and it's all free.

The electric systems on EVs

are generally warranted for 100,000 miles.

So very little maintenance.

You gotta still fill the windshield wiper fluid,

check the brakes.

Of course, there's no oil changes or any of that.

You still have to lubricate the chassis.

So very little maintenance.

Bean_Tiger asks, China makes cheap electric vehicles.

Why can't American shoppers buy them?

The purpose is to protect the American automotive industry.

If those were let in at very little tariff,

it would be very hard

for the US automotive industry to develop EVs,

which is what they're very furiously trying to do now.

The Chinese, as a national policy,

have emphasized new technologies,

not sort of supporting legacy technologies.

So they are the world's global lead

in solar panel manufacturing.

They are making more wind turbines

than I think all the rest of the countries

in the world combined.

And they've moved way ahead on electric vehicles,

way ahead of any other company

with legacy automotive industries

like Germany, Japan, Korea, the United States, obviously.

They have emphasized, in the case of electric vehicles,

learning how to make them

and having a bunch of companies competing with each other

to make very-high quality, very good,

well-engineered electric vehicles.

morganselah asks,

Does carbon footprint of EVs include lithium mining?

Yes, it has to.

Any decent peer reviewable study

of lifetime carbon emissions or pollution

has to include all the mining materials,

processing, manufacturing, everything.

When you drive the car off a lot,

EV has a larger carbon footprint than a gasoline vehicle.

Within a year or two of driving,

it has less and it gets much less over the lifetime.

bullzFromAT asks,

Why are hydrogen cars not more prevalent than EVs?

Just from an energy standpoint or a efficiency standpoint,

hydrogen cars, you start with electricity,

maybe get natural gas, but ultimately,

you're gonna have electricity making hydrogen.

So you lose half the electricity

when you turn it into hydrogen,

and then you've got the energy of the hydrogen

that goes into the car,

instead of plugging in electricity straight into the car.

The car has a tank,

well, that's cheaper than a big battery, great.

But now when you take that hydrogen,

turn it into electricity to drive the motors,

you're losing another half.

So you start with electricity,

you've knocked it in half to get to hydrogen,

you lose another half

to turn it into electricity to run the motor.

When you take electricity

and put it straight into the car's battery,

you're losing maybe 10%, 20%.

So hydrogen, you're using almost four times

as much electricity to drive the car.

Electrical_Hyena5164 asks,

Do EV batteries really outlast the car?

Yes, so they're warrantied for 100,000 miles.

But what does that mean?

That means they have at least 80% of the range

still in the car 100,000 miles after you buy it.

If I had a car that had 200 miles in the beginning,

I'd now have a car that has 160 miles

and still drives great.

Everything's the same.

I just can't go quite as far.

GenExpat asks, What is the lowest tech electric car?

The lowest tech electric car is maybe the Fiat 500e,

which has got 150-mile range battery.

It's a really small car.

It doesn't have any frills.

Really low cost.

You can buy it used, you know,

maybe 8,000 bucks or something.

Nothing wrong with it.

xmorecowbellx, Have Elon's antics affected Tesla sales

in the real world?

Yeah, you could see there's a reduction in sales

that correspond to his high public visibility

and what actions he was taking.

I don't remember the percentage, but there's an effect,

and there's an effect across countries.

So I think it's actually reduced their sales

rather than just leveled them out.

And that gives other US automakers

and worldwide other automakers

a chance to sell more vehicles.

Technogky asks,

Do you still call it the gas pedal or what?

You call it the accelerator pedal.

AlgebraicIceKicg asks,

Why is fast charging only DC?

Why can't we fast charge with AC?

My team at the University of Delaware has developed

a way to do that in the US.

So it used to be that AC charging in the US

was limited to just 19 kilowatts.

That's how fast the power goes into the car.

Just for comparison, a toaster is about one kilowatt.

It's faster than a toaster, but it's only 19 kilowatts.

So if you've got a large tank,

it might take you 12 hours or more to fill it up.

So we've developed 100 kilowatt AC charger,

which is a much lower cost way to quickly fill up a car.

So when you're charging with AC,

use a plug like this in the US now.

If you have a Tesla, it's a little bit different shape.

There'll be some other cars

that are starting to use that too.

But this is a very common AC charging connector.

You plug it into the car, and it starts charging.

On the other end of this wire is a plug,

so you just plug it into an outlet in your garage

or wherever is convenient, on the porch.

You know I've gotten expert

at finding plugs outside of Airbnbs and places.

Plug that in, pull the cable over to the car, plug it in.

That's an AC charging system.

It's cheap.

You can buy something like this for $300 or something.

DC charger is a Coke machine size thing.

It's maybe 20 grand up to 100 grand,

and you put it in with a forklift.

You would never have that at home.

Home charging is always AC.

Fast, en route charging is usually DC.

Thatdud77608645,

When will we have solar panel back windows

for electric cars?

You could run a car off solar,

but you need much more area than the whole car.

You would need solar on the hood,

you'd need it on the trunk in the back,

you'd need it on the roof,

you'd need it on the side.

And to even run for like a normal days driving,

you'd need to leave it outside about three days.

SchweitzerEd asks, Question for EV experts,

is that the actual noise the motor makes,

or do they add that

so they don't silently run over everyone?

Yeah, that whir that you hear

when you hear an electric cargo by,

that's the actual noise that it makes.

nickvanosdol asks,

Anyone got a quick source on

how many consumer EV models already support vehicle to grid,

or even just vehicle to home?

Vehicle to grid means providing power out of your battery

to the power grid.

Now why would you wanna do that?

That has value because it means less strain

on electric lines,

and it means generators, if they're stressed to the max,

they don't have to go further.

They can turn down maybe.

Vehicle to home is using your car to power your house

when the power goes out.

Both of those are becoming much more something you'll see.

A Quora User asks,

How close are we to getting cheap solid-state batteries

to power electric cars?

solid-state batteries are lower weight in mass,

so that's an important advance.

And so there are today cars in China

being sold with solid-state batteries

but there are none sold in the US.

There's a plan to have them sold

to US customers in 2027.

So we're very close to that.

ladevita12 asks,

Why do EV and e-bike batteries keep catching on fire?

They're using lithium-ion batteries.

Lithium is flammable

and burns at a very high temperature,

which makes it hard to put out.

Sometimes if they're not properly managed,

but that shouldn't ever happen.

It means that two or three systems have all failed.

Energy can cause fires and heat

and all kinds of other stuff.

So we have lots of fires with gasoline cars also.

In fact, even though EVs are a new technology,

the number of fires per 100,000 miles driven

in gasoline cars is already much more

than the number of fires in EVs.

So it's just that EVs are novel

and so, oh, EVs caught on fire, so that's news.

Devz0r asks, Will charging electric cars

ever be as fast as pumping gas?

Probably not.

It's just harder to move amount of energy needed

than to move a liquid fuel.

And yeah, maybe you could get the car

to accept a really fast charge.

Like, megawatt charging is a thing.

There's a new standard for megawatt charging,

but then you're gonna have a really high electric bill.

because when you use a lot of electricity at the same time,

they start charging you more money for it.

Awkward-Plenty-24 asks, Is wireless EV charging the future

or just a cool gimmick?

It's just a cool gimmick.

It's really easy to plug in.

It's not necessarily something you have to solve.

You have to have the car positioned exactly over the coils

that are in the pavement or the garage or whatever.

One of the car manufacturers I visited, they said,

A person can't park precisely enough to do this.

We have to have automated parking by the car

to get it positioned exactly where we get enough transfer.

And you are losing energy.

It's not gonna be 100% efficient.

Wire to wire is always going to get more across.

SACtrades asks, What actually happens

to EV car batteries after they die?

When the electric car's done,

you scrap the chassis, the metal

like you would any other car.

But then the lithium-ion batteries are handled separately.

Over time, I think what we'll primarily see is

that the batteries are disassembled

because we wanna reuse that lithium

in other batteries in the future.

So there's a disassembly of the batteries

and separation of the materials,

and then they get used in other products.

For example, other lithium batteries.

A Reddit user asks, By the end of the 2030s,

will electric cars have largely replaced gas-powered cars

in the United States?

End of the 2030s?

That's like 2038, 2039.

In terms of new car sales, personal opinion, yeah,

I mean, there's gonna be very few gasoline car sales

by that time.

It's a superior technology.

You know, once you've driven an electric car,

you say, Oh man, I'm not buying another gas car.

Only people in specialized situations,

they need to drive a long ways,

or there's some reason they need to refuel quickly,

they may keep buying gas cars for a while.

But by the mid 2030s or early 2030s you say,

Oh, well, I'll just buy a thousand-mile range EV

because I don't wanna go back to gasoline.

CallAmbassador4891 asks,

Are EV sales really tanking?

Considering buying one this year

but hearing mixed things.

EV sales are are gonna level out a bit

with the tax credit gone for the next several years.

But EV sales are not tanking.

The rate of growth has dropped a bit.

We're at about 10% of new car sales are EVs.

I don't really expect that to shrink.

MarkJParkerSr asks, Can we retrofit EVs

so these tiny forever batteries will continuously run

an alternator to continuously charge the car's EV battery?

Then you'll never have to pull into a gas station.

Okay, well, this is a perpetual motion machine.

No, you can't make something that works like that.

Lawtoshi asks,

Why aren't gas stations installing EV chargers?

More customers, more revenue, minimal upfront investment.

That's a good question.

Some gas stations are installing EV chargers.

Sometimes people use them and oh, that's fine.

But a gas station's not really

a place you want to hang around for half an hour.

If you're gonna be out there a half hour,

wouldn't you rather be at a 7-Eleven or McDonald's?

You know, someplace where you could have a coffee,

maybe a little food,

or would you rather be someplace that's really smelly

and kind of dirty and grease on the pavement?

No, gas station's not a good place for EV charging.

You're much more likely to have a fast food place

or some kind of small shop

where you can buy a bite to eat, something like that.

That's a much better place for an EV charger.

Okay, that's it.

That's all the questions.

Hope you learned some things for next time.

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