ELECTRIC CARS | How They Work

ELECTRIC CARS | How They Work


– Electric cars are taking over! They’re getting nines in the quarter-mile! Oh my God! But how do they work? The electric car might seem like a relatively new fad hitting the car world. But they are actually a lot
older than you might think! In 1834, Professor Sibrandus Stratingh of Groningen, Netherlands, and his assistant Christopher Becker created a small-scale electrical car, powered by non-rechargeable primary cells. William Morrison of Desmoines, Iowa, built the first successful
electric automobile in the United States in 1891. And by 1897, most of New York’s
taxis were electric powered! Crazy! Before we get into how electric cars work, we need to understand how a battery works. You can’t store electricity, but you can store electrical energy in the chemicals inside a battery. There are three main
components of a battery. Two terminals, or nodes, made of different
chemicals, typically metals, the anode and the cathode. And then there’s the electrolyte, which separates these terminals. The electrolyte is there to
put the different chemicals of the anode and the cathode
into contact with one another in a way that the chemical
potential can equilibrate. (Comical overlay of the term words) During the discharge of electricity, the chemical on the
anode releases electrons to the negative terminal
in ions in the electrolyte. Meanwhile, at the positive terminal, the cathode excepts electrons, completing the circuit
for the flow of electrons. Converting stored chemical energy into useful electrical energy. That’s what generates an electric current! It took a while before we’d
improved battery technology enough that we could power a vehicle to travel practical distances. But guess what? We got ’em! (clap) The batteries in most hybrids and most fully electric cars, I am looking at you, Elon, look like this. This metal case holds a long spiral, comprising three thin
sheets pressed together. Inside the case, these
sheets are submerged in an organic solvent, often ether, that acts as the electrolyte. The separator is a very thin sheet of micro-perforated plastic. The positive electrode is made of lithium cobalt oxide, the negative electrode is made of carbon. When the battery charges, ions of lithium move through the electrolyte, from the positive electrode
to the negative electrode, and attach to the carbon. During discharge, the
lithium ions move back to the lithium cobalt
oxide from the carbon. It’s the same principle
as any other battery but because these batteries can store so much electric energy
as chemical energy, lithium-ion batteries are
what help electric cars make the leap from novelty to reality. The great thing about
lithium-ion batteries is that they can recharge over, and over, and over, and over, and over. The lithium-ion batteries
in the Tesla battery pack are actually super similar
to the rechargeable batteries that you’d find at the store. They’re also commonly used in vapes. (car speeding) (breathing out smoke) Each cell contains 4.2 volts and about 30 amps. What does that mean? Electricity flows like water, so let’s think of where we store water, in a reservoir! Here’s a reservoir behind a dam. The water back here is like
the voltage in a battery. It’s like a stored charge. If we let some water out of the dam, we can measure the rate of flow. In a battery, this
current’s measured in amps. On a battery, amps measures capacity. That’s pretty much how quickly the energy can flow out of it. If I put more water in the dam, the flow can still be limited. So, a greater voltage can
be limited by amperage. Also, if we increase the flow without increasing the charge, we run out of juice before
it does us any good! In a battery cell, amps measures capacity, basically how well the current can flow. Wiring cells together can increase either voltage, the energy stored, or amperage, the flow of current, Or, both! If I wire a battery series,
I am doubling the voltage while maintaining the
same capacity rating. If I wire a battery in parallel,
I am doubling the amperage while maintaining the same voltage rating. 7,104 cells in the Tesla Model S battery are wired in a combination
of parallel and series, over 16 modules to increase both voltage and amperage to 1500 amps and 400 volts! That’s a lot of juice! But how do they move? Back in the early 1800s,
everybody was anybody was screwing around with electricity and the resulting currents. So it wasn’t long before people realized wrapping wires and sending
currents through them generated magnetic fields. If you’ve ever tried to touch
two magnets’ north ends, (buzzing sound) well you know that there is a tangible, physical force that magnetic
fields can generate. Electric motors use this
force to actuate motion. The Tesla Model S uses a motor, first invented by Nikola
Tesla about 100 years ago, the induction motor. The motor consists of two parts, the rotor and the stator. The rotor is a series of conduction bars, short-circuited by end rings. A three-phase AC pulse
is given to the stator. This alternating current
produces a four-pull, rotating magnetic field, or, RMF. The electricity running through the stator induces current on the rotor’s metal bars. Just like the magnets can attract or repel to cause movement, the rotating field of the
stator causes movement in the now-charged rotor. In an induction motor, the rotor is always just behind the RMF. The speed of the rotor is
determined by the frequency of the AC current through the stator. When you hit the gas, you’re actually increasing
the frequency of current. An inverter switches the direct current from the batteries to
an alternating current, to drive the motor. It sits right by the motor
and it’s got all the guts to determine the frequency of current, which determines the speed of the rotor and the amplitude of the current, which effects the power
output of the rotor. That’s determined by a
variable frequency drive attached to all this, right here. The only points of
contact are the barrings that keep the rotor in place. There’s no other touching going on between the rotor and the stator. So it’s hard for them to wear out. And unlike a conventional engine, whose usable torque dwells only
within a limited rev range, usually under 8,000 RPM, the Tesla motor can
effectively produce force to a rev range up to 18,000 RPM. So there’s no need for
shifting or torque converters. Also unlike conventional
engines that convert up-and-down or side-to-side motion of the pistons to rotational movement, the induction motor produces
exclusively rotational force, which means, almost all that
can be turned to forward motion when the wheels hit the road. Traditional internal combustion engines can weigh up to 600 pounds. A Tesla Model S motor can
generate 362 horsepower, and only weighs about 70 pounds. But, you gotta remember they’re getting all that
juice for those horses, from a 1200 pound battery. (car skidding) Even with that massive battery, the Tesla Model S is
443 pound feet of torque and 416 horsepower allows you
to get to 60 miles-an-hour in 4.2 seconds, in a Sedan! Tesla says their biggest concern
discharging all that energy and spinning the rotors
at 18,000 RPM, is heat. So, most of the components
including the motor, the frequency drive, and the battery, are liquid cooled so they don’t overheat. Oh, and here’s the other
thing about the Teslas. The induction motor,
when it’s not producing movement at the wheels,
can be spun by the wheels, which makes it one like
the alternator in your car, recharging the lithium-ion battery! So more motors means yes, you’re getting more
power through the wheels, but it also means more charge
coming back to the battery when you’re rolling and breaking. It’s responsible! But making these cars and charging them will also cause emissions. There’s no such thing
as totally green cars. Well, you’re right. There is no such thing as
a truly carbon-neutral car. But, even factoring the carbon created manufacturing the cars, electric cars have a significantly
smaller carbon footprint than gasoline-powered cars. And the process is getting
more efficient all the time. If you wanna help Donut
make more great content, check out Brilliant.org! They sponsored this episode. Heck, not just sponsored, but the information on Brilliant actually helped us write this one! I brushed up for this
episode by going through practice problems for
electricity and magnetism. How do you think I learned how to do this? (Buzzing, laughing) And then, I searched the
user-generated explanations to further my understanding
of how this all works. Actually working through problems makes the concepts so much clearer. More than just reading about ’em. The community wants to help you, to challenge you, and inspire you. What better way is there to get excited about math and science! Go to Brilliant.org slash science garage and sign up for free. Also, the first 200
people to go to the link will get 20% off their
annual premium subscription. I’ll see you there! Brilliant! Hit this button to subscribe to Donut, so you never miss an
episode of Science Garage. Follow me on Instagram @Bidsbarto, follow Donut @DonutMedia. Get yourself some shirts, we got plenty new stuff
coming at shop.donut.media. We talked about vaping, check out this up to speed on the WRX. Also, check out this new car
show on the Tesla Model Three. Don’t tell my wife I still
put batteries on my tongue. It tingles.