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Electric Vehicles:

Sustainable Transportation of the Future

Goal: To learn about electric vehicles, how they work, and how they are a sustainable transportation

Today’s ET Lab is going to introduce you to Electric Vehicles. Does anyone’s family own an electric vehicle?

What are the advantages of an electric vehicle? How about disadvantages?

There is a lot of talk today about moving away from gas powered cars because burning gasoline or diesel fuel produces emissions that are harmful to our environment and contribute to global warming. The most popular alternative is the electric vehicle. In fact, General Motors and many of the other major car companies are committed to moving away from gas powered vehicles and eventually only offering electric vehicles. As you can imagine this effort will require the work of many engineers. There is an awful lot of engineering that goes into making any type of car and working to replace the traditional internal combustion engine with battery power presents many engineering challenges.

(If the students started the workbook before the Intro Presentation, the engineer might discuss the answers to the workbook questions.)

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College:

Notre Dame

Major:

Electrical Engineering

Kelsey Farr

Breakout Development Team

College:

Notre Dame ‘23

Major:

Mechanical Engineering

Caroline Gillespie

Erik Einset

College:

Cornell BS ‘86

U. Of Minnesota PhD ‘91

Major:

Chemical Engineering

Industry Experience:

GE, GIP - 30 years

College:

SUNY Polytechnic Institute ‘23

Major:

Mechanical Engineering Technology

Julian Centeno

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When we think of electric vehicles, we tend to think of passenger cars (sedans, SUVs, etc.). But, an electric vehicle is any vehicle that uses electric propulsion to move!

Brainstorming: What is an Electric Vehicle?

Trolleys
Electric city transit buses
Drones
Electric-powered boats
Electric trains, monorails

Some less-often thought of

EVs include:

So let’s think about what an electric vehicle (or EV) is. Because Tesla is so often in news these days, we generally think of a passenger car when we hear “electric vehicle” and consider it to be a relatively recent invention. It turns out that electric vehicles have been around for quite some time. An electric vehicle is any vehicle that is powered by electricity, or uses an electric propulsion system. Here, we have listed some less-often thought of EVs:

Trolleys (like the Streetcars in New Orleans) connect to electric power lines that run above the trolley car.

There are also electric city transit buses (like those that operate in Boston) that offer a much more sustainable option than traditional busses that run on diesel fuel.

Drones are battery powered, too. Currently, there aren’t many other aircraft that are electric and this is because the batteries required to power such a heavy vehicle would be very large. One of the advantages of the internal combustion engine is that it can generate a lot of power.

Electric-powered boats represent a very small percentage of the boat market today but are expected to grow as the technology improves.

Electric trains and monorails common at airports and theme parks - including Disney World - are another type of EV.

Can anyone else think of another type of vehicle not listed here that could use electric power? (electric bikes or scooters)

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The first electric motor

The first successful electric vehicle

Fun Fact

Electric-powered motors were invented in 1828 by a Hungarian man named Ányos Jedlik, and the first practical version of an electric vehicle was invented in the US in 1891. It was a 6-passenger wagon that could go up to 14 mph.

History of Electric Vehicles

**If students have done pre-work assignment, then slides 5-10 will help reinforce material in the video. Otherwise, review material on slides with students as an introduction to challenge.**

As the video explained, the concept of electric-powered vehicles has been around for almost 200 years! Perhaps even more surprising is that originally EVs were even more popular than gas-powered vehicles. But, there were limitations in how far and how fast vehicles powered by electric motors could go. This was because of the battery technology available at the time. EVs also took longer to recharge and were more expensive when compared to their gasoline-powered counterparts. So, as the oil and gas industries took off and more efficient gasoline engines were developed, gas and diesel vehicles essentially completely replaced electric vehicles.

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Fun Fact

Because EVs don’t use gas, their “fuel economy” is measured in terms of miles per kilowatt hour (kWh), which is a measure of miles driven per unit of energy used by the battery. This is different than the typical “miles per gallon,” or MPG, fuel economy measure used by ICE (internal combustion engine) vehicles.

Electric Vehicles vs “Traditional” Vehicles

Another advantage of Electric Vehicles discussed in the video is their simplicity. This graphic has a lot of information on it, and you don’t need to understand all of the parts that are listed. The most important thing to understand is that EVs require fewer parts and less complexity than the drivetrain of internal combustion engine (ICE) vehicles. The “drivetrain” is the set of parts that facilitate the vehicle’s propulsion and motion.

[In the case of the gas powered engine, you can see it involves many different parts - you need some cooling, a starter to get the engine going, an exhaust system to treat the gasses produced when burning the fuel, a generator to recharge the battery needed for the engine starter, a fuel tank, and pumps to deliver the gas and oil to different parts of the system.

The electric vehicle is much simpler; you just need a charger, the battery itself and a motor.]

Fewer parts in an EV means less maintenance is required on the vehicle over time, as compared to and ICE vehicle. There are also financial savings for EVs because the owner does not have to purchase gas to fill up the tank of an EV! We’ll talk more about that in the next slide.

https://avt.inl.gov/sites/default/files/pdf/fsev/compare.pdf

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Cost to “Fuel” EVs vs ICE Vehicles

EV Efficiency (miles/kWh)	Cost of Electricity (per kWh)	Fuel Economy of Gas-Powered ICE Vehicle (mpg)	Cost of Gas (per gallon)
3	$0.10	22	$2.50

In order to compare the cost of travel for an electric vehicle versus a vehicle with an Internal Combustion Engine, we need to look at how far you can travel for a $1. We can’t use the traditional miles per gallon metric because electric vehicles don’t use gallons of gasoline. Based on an electric vehicle efficiency of 3 miles/kWh and the cost of electricity at [about 10] cents per kWh, an electric vehicle will travel about 30 miles for $1.00. Based on an average of 22 mpg for gasoline vehicles and a gasoline cost of [$2.50]/gal, the gasoline-powered vehicle will go about 8.8 miles. So, the distance that can be traveled for a fuel cost of $1.00 is more than three times as far with an electric vehicle.

But, as we know, gas prices can be more expensive, and are currently at least $2.50 per gallon. The average price of gasoline in NYC is just under $4. This means that in terms of cost, it is even cheaper to drive an electric vehicle compared to combustion engine vehicles. An EV can travel much further than an ICE vehicle per dollar spent “fueling” the car (where fuel is either electricity or gas/diesel).

It should also be noted that electricity prices vary by what part of the country you’re in, but are less than 20 cents per kWh on average.

https://avt.inl.gov/sites/default/files/pdf/fsev/compare.pdf

https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a

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Characteristics of Electric Vehicle Batteries

Regenerative braking

When braking, the kinetic energy that was previously propelling the vehicle is now reversed, so energy is going into the electric motor, then back into the battery for later use.

Idle-off

The EV’s battery will turn off when the vehicle is at a stop or idling.

How do EVs optimize energy?

The characteristics of electric vehicle batteries provide additional advantages in terms of energy savings.

First, when a car is moving it has kinetic energy. When you hit the brakes, you transfer that kinetic energy into something else. In traditional gas powered cars, you transfer the kinetic energy into heat, as you slow down through friction. Electric vehicles are able to transfer the kinetic energy into another spinning generator that can recharge the car’s battery. This is called “regenerative braking” and is a good way to conserve energy.

[Regeneration of energy is not perfect. Currently, EV batteries are only able to accept about 20% of the total kinetic energy that could potentially go back into the battery when braking. This is due to the limited amount of energy the battery can accept in a short period of time.]

Second, it is very easy to turn an EV battery on and off (similar to how a light switch works, it is almost instantaneous), so you can save energy by using this idle-off feature without losing any performance.

More on regenerative braking, including the diagram in the next slide, here: https://www.delphiautoparts.com/usa/en-US/article/regenerative-braking-explained

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Regenerative Braking Explained

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Range depends on many factors, including battery capacity, weather conditions, vehicle design/aerodynamics, driving speed, and more.

Honda Fit → 80 miles
BMW i3 → 175-189 miles
Tesla → 150-400 miles

Charging stations are typically 240 volts. At this voltage, it can take up to 10-12 hours to charge an EV battery than has been depleted.

Characteristics of Electric Vehicle Batteries and Charging

Typical EV Range on a Full Battery Charge

EV Charging Stations

Some of the characteristics of electric vehicle batteries also present challenges, including the time it takes to recharge the battery and how long the battery lasts.

On the top here, you can see the range of a few different vehicles. There has been a big improvement in battery storage capacity with Tesla’s range now similar to that of a traditional gas powered vehicle.

Finding an electric vehicle charging station can also be an issue, as there is not yet the pervasive network of facilities that exists for gas stations. There is a government push to increase availability so over time this should improve.

The time it takes an EV battery to charge is another hurdle in EV adoption. How quickly an EV battery can be charged is based on the voltage being used for charging. It can take a 120-volt charger as long as 3 days to charge a depleted battery. On the other hand, it can take as little as 30 minutes if a 480-volt DC fast charger is used. However, 240-volt chargers are the most common, and typically take up to 12 hours for a full charge if the battery is depleted. To avoid these long charging cycles during inopportune times of the day, EV owners usually leave their vehicles plugged in overnight to charge. This way, their battery will be “topped up” each night.

Long charging times become more of an issue when traveling long distances, like on a road trip, when the EV will need to be recharged during the trip. DC fast chargers are currently the best solution to the problem of otherwise long charging times, but not all EVs can use them, and 30 minutes for a charge is still much longer than the typical 5 minutes it takes to refill a gas tank of a gas-powered vehicle. So, this is a big area for improvement for electric vehicles in the near future!

https://www.kbb.com/car-advice/how-long-does-take-charge-electric-car/

If there is more interest in exploring the different factors that influence an electric vehicle’s range, check out this website about different Tesla models: https://teslike.com/

https://www.hydroquebec.com/transportation-electrification/electric-vehicles/range.html

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A group of undergraduate and graduate students at The Ohio State University worked with Venturi Automobiles, an electric vehicle manufacturing company, to create a vehicle that broke the electric vehicle land speed world record in 2016.

The team of engineering students and engineering professionals designed the Venturi Buckeye Bullet 3, which reached an average top speed of 341.1 mph!

Exciting Things Engineers Have Accomplished!

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There are 3 types of batteries most commonly used in electric vehicles:

Lithium ion
Nickel-metal hydride (Ni-MH)
Lead acid

What Types of Batteries are Used in Electric Vehicles?

Since we’ve mentioned a couple times how critical the battery is to electric vehicles, we wanted to provide you with a little more information on battery technology.

A battery is a device that we’re all very familiar with as it’s used in many devices that we use every day. Basically a battery takes chemical energy stored in the device and converts it into electrical energy. As electric vehicles have developed, 3 types of batteries have been used: Lithium Ion (which are the most common currently), Nickel-metal hydride (which you’ll be using in this lab) and Lead acid (which is the battery found in traditional gas powered cars.)

One of the things that is driving the advancement of electric vehicles is the improvement in battery technology.

Lithium Ion batteries were first developed in the 1990s and now are the most widely used rechargeable batteries in electric vehicles and many other electrical devices. They have a longer lifespan than Nickel-metal and lead acid batteries and are also generally smaller and lighter, which is a big advantage when trying to build an efficient electric vehicle. Another big advantage of lithium ion batteries is they don’t lose their charge when not in use as some other rechargeable batteries can.

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How Do Rechargeable Batteries Work?

This slide shows you what a Lithium-Ion battery looks like. Battery technology is pretty complicated and involves material science and chemical engineering, so we’ll just discuss a few of the key elements of a battery.

The battery is made up of several individual cells that are connected to one another. Each cell contains three main parts: a positive electrode (a cathode), a negative electrode (an anode) and a liquid electrolyte.

Just like alkaline dry cell batteries, such as the double A’s used in clocks and TV remote controls, lithium-ion batteries provide power through the movement of ions. Lithium is extremely reactive in its elemental form. That’s why lithium-ion batteries don’t use elemental lithium. Instead, they use lithium compounds, like lithium metal oxide and lithium carbon (or graphite) that allow lithium ions to easily flow from anode to cathode and vice versa.

From Let’s Talk Science, How Does a Lithium Ion Battery Work

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How Do Rechargeable Batteries Work?

Example of Lithium ion battery

When discharging, the battery provides power to the load (which could be a motor or your cell phone) via electrons flowing from the negative terminal (anode side) of the battery to the positive terminal (cathode side) of the battery. At the same time, positively charged lithium ions (Li+) move from the negative anode to the positive cathode through the porous electrolyte in the middle of the battery (see the red arrows showing the Li+ ions moving through the electrolyte in center of figure). As long as Li ions keep flowing, electrons will continue to flow, providing an electric current to power the load. When there are no more Lithium ions to flow, the battery is fully discharged and will have to be connected to a power source to be recharged.

When the battery is being charged, the power source connected to the battery causes the electrons that have been accumulated in the cathode of the battery to flow back to the anode,while the Li+ ions move from the cathode to the anode back through the electrolyte.

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Due to the demand for electric vehicles, battery manufacturing is on the rise, even in the midst of the pandemic.

Battery Manufacturing

Proterra Electric Transport Company

https://www.40northventures.com/next-generation-proterra-ev-battery-manufacturing-facility-opens-in-los-angeles-county/

Manufacturing batteries is a big industry that involves a lot of engineers. Here is an example of one such company.

Proterra is a heavy-duty electric transportation company based in California. The company specializes in batteries made for all-electric buses, which require a higher energy capacity, for longer range, and higher power density, for faster charging time, compared traditional EV passenger car batteries. This is because buses are much larger and heavier than passenger cars, and they often run more frequently.

Proterra opened a new battery manufacturing facility in LA in December of 2020, showing that the EV battery industry is growing, even in the midst of the COVID-19 pandemic.

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What You’ll be Working on in Today’s Lab

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In this lab, you will use a solar cell to charge a battery.

This is a model of using renewable energy in the real world to provide power to an electric vehicle’s battery.

Modeling Real World Applications

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Pretend you are an electrical engineer. How can you use the Engineering Process to create a solar powered system to charge an electric vehicle?

THINK:

What action would you do with each step of the process?

Click HERE for more information on the Engineering Design Process!

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The Components of your EV Charging Station

Jumper wires

Solar PV Cell

1.5V

400mA

Max power 0.65W

Ni-MH battery

1.2V

Rechargeable

Diode

Battery holder

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Note: The direction the diode is connected matters! The grey stripe of the diode should be connected closest to the battery connection, as pictured.

Electrical Circuit Model of your EV Charging Station

The solar cell is your power source (when the sun is shining on it) to the Ni-MH battery
The diode prevents current from flowing back into the solar cell (which would damage the solar cell)
The battery is being charged by the solar cell

Battery

(in battery clip holder)

+

-

Current Flow Direction

Diode

Current Flow Direction

Once the battery is sufficiently charged, you can disconnect it from this solar cell and diode “charging station” and use it to power a mini electric vehicle!

This is the circuit you are going to build.

You are going to connect the diode to the positive side of the solar cell and to the positive terminal of the battery. Please note that the direction the diode is connected matters! The grey stripe of the diode should be connected closest to the battery connection, as pictured. The diode only passes current in one direction so connecting it this way prevents current from flowing back into the solar cell - which would damage it.

For your reference, the new NiMH battery is usually pre-charged to a certain amount, so it will work ‘out of the box’ to power circuits. However, if you drain it or want to get it more completely charged, you’ll have to use your solar cell to convert the energy from the sun to stored electrical energy in your battery!

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Building Your EV Charging Station

Now, wait for your battery to charge. Once it’s sufficiently charged, you can use it to power an electric vehicle that you construct!

Diode

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The Components for Building your EV

Motor and Holder

Propeller

Wires

Find other household materials for your EV (cardboard, plastic bottles, etc)

Single battery holder �(see note)

Ni-MH battery

1.2V

Rechargeable

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Your kit contains materials for electric propulsion using a fan. But since you only have one NiMH battery (1.2V), you don’t have a lot of power!

Can you fabricate an EV that can move with such a small power source?

(If you’re building a boat, be careful to not get the motor wet as that will ruin it!)

Building An EV

Recycle materials you can find around the house to build an Electric Vehicle!

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Building Your EV - Some Ideas to Spark Your Imagination

https://www.makerspaces.com/propeller-car/

For more inspiration, try Googling:

“Car with plastic bottles fan propulsion” or

“Toy boat from plastic bottles”

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Building Your EV - More Ideas to Spark Your Imagination

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Continue to Explore

If you liked today’s breakout, you may be interested in these topics:

Engineering Disciplines Relevant to today’s electric vehicle breakout:

Electric and hybrid vehicles
Vehicle design
Energy storage - batteries
Solar energy
Sustainable transportation
Sustainable energy

Electrical Engineering
Mechanical Engineering
Chemical Engineering
Materials Science and Engineering
Energy Systems Engineering