Overview and Background Information
The price of oil is up; gas guzzling cars are out and the race for a fuel free practical electric car is on. This includes the usual suspects of Japan, Detroit, and Germany, but what shocked most car enthusiasts was a new company with virtually no experience building cars has entered the race… Silicon Valley. The jury is still out as to whether or not electric cars can ever really be practical, but the computer geeks in California are betting that their inventiveness can beat out Detroit’s cumbersome bureaucracy in producing a viable electric car. One of the reasons electric cars have never taken off has been battery technology. A few years ago people began to wonder, “why not use the batteries that they put in laptop computers called lithium ion batteries?” That’s when the environmentally conscious high tech industry in California jumped in.
Figure 1 Tesla Roadster
Figure 1 is the first all electric roadster made by Tesla Motors, a small startup in northern California. The chairman of Tesla Elon Musk says the Tesla Roadster can accelerate from zero to sixty in approximately 4 seconds and is propelled by 6,831 rechargeable lithium ion batteries and not a single drop of oil. Elon Musk helped launched Tesla 5 years ago with no experience at all in the car business and now has over 1,000 orders for this high tech, sporty roadster. While the roadster may be fuel friendly, it isn’t so friendly on the old pocketbook. When it comes to the initial investment you’ll have to make in order to park one of these vehicles in your garage. The Tesla Roadster some with a hefty price tag of $109,000 which chairman and CEO Elon Musk calls “a steal with twice the efficiency of a Toyota Prius.”
From the beginning Musk wanted to prove that the innovative and nimble Silicon Valley could build a better green car than what he called “the lumbering bureaucratic Detroit.” While the price of oil is down most likely due to the current election, as we learned in class, prices are believed to reach an all time high between the years of 2026 and 2047. This doesn’t even take into account the greenhouse effect, which even furthers the importance of “not just an all electric car but a green friendly vehicle.” Tom DuPont of DuPont Registry furthers these thoughts by stating that “despite the luxury marketplaces’ tradition of resisting environmental chance, the technological advancements and social implications that go along with environmentally friendly vehicles are creating a social consciousness and greening the exotic car market.”
This year, 2008, the a new innovative electric roadster wins Gold International Design Excellence Award sponsored by Business Weekly magazine and the Industrial Designers Society of America. With this accomplishment, practical electric and future vehicles are not too far out of the imagination. Quoted from Tesla Motors, “The very definition of automobile is freedom of motion. The word itself originated as a literal way to define a vehicle that moves under its own power without need for another vehicle – such as a horse or locomotive. Today the definition of automobile often includes association with an internal combustion engine. We’re here to change this definition one car at a time. The world will once again use the automobile to transport us free of convention. Tesla Motors will be part of this liberation. The Tesla Roadster moves not only under its own power, but ultimately free of the existing and increasingly troublesome petroleum-based infrastructure, [((bibcite (http://www.teslamotors.com/learn_more/our_company.php)))].”
Founded in 2003 by Martin Eberhard, Marc Tarpenning, and Elon Musk, Tesla motors began as a small company that designed and developed new, original vehicles for car enthusiasts. Elon Musk, Chairmen, Product Architect, and CEO, has been the main funding source for the business since the beginning. He is better known for co-founding PayPal, Zip2, and founding SpaceX. Now in 2008, Tesla Motors is taking flight and has well over 250 current employees. Their mission, to create the most energy-efficient car on the planet while blending a beautiful sleek style with high performance. Their first production car, the 2008 Tesla Roadster, certainly accomplishes this task.
To put everything into perspective, listed below are some general specification to illustrate the performance of this new ground-breaking electric vehicle.
2009 Tesla Roadster Performance Specifications*
Style 2-seat, open-top, rear-drive sports car
Drivetrain Single speed fixed gear with electrically actuated parking lock mechanism and mechanical lubrication pump
Motor 375 volt AC induction air-cooled electric motor with variable frequency drive. Output 248 peak horsepower (185kW) and 276 ft/lbs (375 nm) of torque. Redline 14,000 rpm.
Chassis Resin-bonded and riveted extruded aluminum monoquoque. Four-wheel independent
Suspension Featuring upper and lower unequal length wishbones and co-axial coil spring telescopic dampers.
Brakes Hydraulically operated. Tandem master cylinder with vacuum servo and anti-lock braking system.
Acceleration 0 to 60 mph in under 4 seconds
Top Speed 125 mph (electronically limited)
Range About 220 miles (based on EPA combined city/highway cycle)
Battery Life Five years or 100,000 miles
Battery Custom microprocessor-controlled lithium-ion battery with 6,831 individual cells. Weight 992 lbs.
Full Charge About 3.5 hours using the Tesla Motors High Power Connector.
* Specifications as of Summer 2008.
Motor 375 volt AC induction air-cooled electric motor with variable frequency drive.
Max Net Power 248 HP (185 kW) @ 4500-8500 rpm
Max rpm 14,000
Efficiency 92% average, 85% at peak power
Torque 276 ft/lb (375 Nm) @ 0-4500 rpm
Transmission Single speed fixed gear with electrically-actuated parking lock mechanism and mechanical lubrication pump
Overall Final Drive 8.28:1
Reverse Reverse direction of motor, limited to 15 mph
Final Drive Ratio 3.12:1
Front Suspension Independent. Upper and lower unequal length wishbones. Co-axial coil spring/telescopic damper. Sway bar.
Rear Suspension Independent. Upper and lower unequal length wishbones. Co-axial coil spring/telescopic damper. Sway bar.
Brakes Hydraulically operated. Tandem master cylinder with vacuum servo and anti-lock braking system. Front and rear ventilated disc. Cable operated self adjusting hand brake on rear calipers.
Wheels Type Forged Light alloy
Size - front 6J x 16
Size - rear 7.5J x 17
Tires Type Yokohama Neova AD07 LTS
Size - front 175/55 R16
Size - rear 225/45 R17
Dimensions Overall length (in. / mm) 155.4 / 3946
Overall width - incl. mirrors (in. / mm) 72.9 / 1851
Overall height (mid-laden weight) (in. / mm) 44.35 / 1126.5
Wheelbase (in. / mm) 92.6 / 2351
Track - front (in. / mm) 57.7 / 1455.6
Track - rear (in. / mm) 59.0 / 1484.5
Curb weight (lbs/kgs) 2723/1238
Leg Room (in./mm) 42.0 / 1067
Front Head Room (in./mm) 36.7 / 932
Front Shoulder Room (in./mm) 26.0 / 660
Unlike the current design of automobiles, the Tesla Roadster is made up of only four main systems, the Energy Storage System (ESS), the Power Electronics Module (PEM), an Electric Motor, and a Sequential Manual Transmission.
Energy Storage System (ESS)
The Tesla Roadster contains a collection of 6,831 lithium-ion batteries which takes the place of an internal combustion engine. They are located in the rear of the vehicle mounted in 11 sectors. A computer then controls each sector to ensure proper function of charging and discharging of the energy. These batteries are pretty much the same battery that one would find for a present day laptop computer. Together, the total weight of this system is approximately 1,000 pounds, which makes up the majority of the car’s overall weight. These batteries are said to be able to provide five times the energy-density of other batteries.
Since the roadster runs strictly on electricity, it must have a way to be recharged. Tesla Motors has come up with two different ways to accomplish this task. One possible way is to have a certified electrician install a “recharging station” in one’s home. This station consists of a 220 volt, 70 amp outlet that can recharge those 6,831 batteries in just about 3.5 to 4 hours from completely dead. The second option involves a mobile connection kit from Tesla Motors that can be plugged into any standard outlet. The vehicle can then be plugged into this kit to allow the charging process to occur. This option will take much more time to charge the vehicle depending on the outlet configuration. A standard 110 volt outlet will take approximately double the time of the 220 Volt source [((bibcite (http://auto.howstuffworks.com/tesla-roadster.html)))].
Now some may be thinking, "Well, will charging this car cause a large increase in a home electric bill?" The Tesla Roadster will cause a slight jump in an electric bill, but it sure is not what one would expect. Tesla Motors claims that it will cost roughly $0.01 per mile driven. Since the car can travel over 220 miles on a single charge, that equates to $2.20 for one complete charge. This sounds way to good to be true. Well, it just does not stop there. Tesla Motors also states that depending on where you live, you can also be entitled to the following:
- Single-occupancy access to all carpool lanes
- Income tax credit (awaiting new legislation)
- A luxury car that's fully exempt from the luxury car tax
- Free parking at charging stations at LAX
- No parking meter fees in an increasing number of major metropolitan areas
The $109,000 price tag starts to seem more and more reasonable.
Power Electronics Module (PEM)
The PEM system, also locateded in the rear of the vehicle, is a complicated power inverter and charging system. Its job is to convert DC power to AC power by using 72 insulated gate bipolar tansistors (IGBTs). First generation electric powered cars did not use this exact technology which caused a much lower power output than the new Tesla Roadster.
In addition, the PEM system is responsible for controlling the voltage levels, RPM’s of the motor, torque, and the regenerative braking system. The regenerative braking system helps provide power to the batteries by using energy from braking to slow the car down. This kinetic energy is transferred back to the EES system, helping to improve the overall efficiency of the EES, PEM and motor by 85 to 90 percent. In turn, this allow the electric motor to produce a maximum of 185kW of output power [((bibcite (http://auto.howstuffworks.com/tesla-roadster.html)))].
The Electric Motor
The Tesla Roadster motor is a 3-phase, 4-pole electric induction motor. The motor is equivalent to the size of a large watermelon and weight about 100 lbs. What really separates the power of a Tesla Roadster to a sports car is very unique. At 0 rpm, the roadster can generate its maximum torque of 276 ft-lbs. This motor is also capable of reaching a 14,000 rpm redline, which most combustion engines cannot do. When the Roadster is put on the drag strip against its competition (Viper, Ferrari, Lamborghini, Porsche, Mclaren F1, ect. ), this unique feature of the Tesla motor gives the car the ability to make these prominent sports cars look like a joke. The car dashes off the line and all of its power which is transfered to the wheels goes directly to work. The roadster does not have any traction problems from acceleration due to its incredible power band, unlike these sports cars and finishes the race in first. Tesla Motors states that they play a trick on all of their new customers when they sit in the car for the first time for a test drive. "A favorite trick here at Tesla Motors is to invite a passenger along and ask him to turn on the radio. At the precise moment we ask, we accelerate. Our passenger simply can't sit forward enough to reach the dials!"
Since the motor to this vehicle is so simple, it requires a simple transmission. The Roadster has just three gears. There are two forward gears and one reverse gear. The shifting is manual but there is no clutch required. If there is no clutch, then there is no stalling, jerking, or a time large gap to switch gears [((bibcite http://auto.howstuffworks.com/tesla-roadster1.htm))].
In the new and upcoming 2009 models, a new transmission is going to be used since some slight problems have come about. Its going to reduce the two forward gears to just one and still include the one reverse gear. Because of this change, it will slightly limit the performance of the vehicle's acceleration. To make up for this, Tesla Motors is going to "beef up" the motor and add an new coolant system to compensate for the loss. All 2008 model owners will have a recall in which Tesla will install the new motor and transmission free of charge.
To put into perspective just how efficient this vehicle is, it must be compared to other modern fuel efficient vehicles in a well-to-wheel efficiency test. Tesla Motors claims and stands by their word that their roadster presents double the efficiency of the top hybrid cars on the market today and emits one-third of the carbon dioxide. When this roadster is compared to our exotic sports cars, it has shown to be six times as efficient and emits one-tenth of the pollution. The following data below shows a comparison of the Tesla Roadster with the latest fuel efficient vehicles [((bibcite http://www.teslamotors.com/efficiency/well_to_wheel.php))].
Our modern hybrid vehicles can get up to 55mpg. This seems incredible, but the Tesla Roadster blows the competition out of the water. It is said by Tesla Motors that this roadster contains a equivalent of approximately 2.1 gallons of petroleum. After traveling for 220 miles, this shows to be a unbelievable 100+ mpg equivalent, and costs a mere $2.20 for a "fill up"!
In conclusion, the Tesla Roadster has shown to a an astonishing vehicle that provides reliability, efficiency, and performance to its owner. Its an environmentally friendly machine that gives the driver an adrenaline rush as if driving a Lamborghini with the top down at 100mph. Its overall engineering has separated this roadster into its own category. No other fuel efficient automobile on the market today can compare. Tesla’s business plan is build off of the views of their key investors who believe that new and innovative technology can be very pricey. As technology advances, the Roadster can move down the market making it available to a wider range of people. It is for this reason that Tesla marketed its first vehicle as a high end sports car, targeted to a very high end clientele. Is its price worth every penny? You can be the boss of that.