2008 Tesla Roadster

(from Tesla Motors)  Electric Power:  Drive Quickly, Tread Lightly

Most electric vehicles operate under the assumption that driving is merely a necessary evil if you need to get someplace you cant reach on foot or bike. The result has been cars that are designed, built, and marketed in ways that refuse to glorify driving.

We respectfully disagree. We believe driving is exhilarating. Just watch any child on a go-cart and the joy is plain to see. And when you can soar along at top speed, knowing the only oil in the car is in the transmission, the only emissions are the songs from the radio, the ride becomes more enjoyable still.

The Ultimate Multi-Fuel Vehicle

Electric cars equal freedom. Not simply from oil reliance, but from dependence on any specific power source. Electric power can be generated from natural gas, coal, solar, wind, hydro, and nuclear sources or a combination of all of them without changing the design of the car. No matter how or when the world changes, the car adapts, making it immune from obsolescence.

We foresee a day when all cars run on electric power and when people will struggle to remember a time when a love of driving came with a side order of guilt.

No More Tradeoffs

Up until now, if you wanted a car with amazing gas mileage, youd pick something like the leading hybrid; but when you pressed down the gas pedal to zip up a freeway on-ramp, you'd likely be a little disappointed it takes over 10 seconds to reach 60 miles per hour. On the other hand, if you demanded the 0 to 60 times of a $300,000 supercar, you'd wind up with an embarrassing 9 miles to the gallon in the city.

How It Works

When you build a car that's electric, you start with one built-in advantage: Electric cars just don't have to be as complex mechanically as the car you're probably driving now. Sophisticated electronics and software take the place of the pounds and pounds of machinery required to introduce a spark and ignite the fuel that powers an internal combustion engine.

For example, the typical four-cylinder engine of a conventional car comprises over a hundred moving parts. By comparison, the motor of the Tesla Roadster has just one: the rotor. So there's less weight to drive around and fewer parts that could break or wear down over time.

But the comparison doesn't end with the counting of moving parts. The engine and transmission of a conventional car also need lubricating oils, filters, coolant, clutches, spark plugs and wires, a PCV valve, oxygen sensors, a timing belt, a fan belt, a water pump and hoses, a catalytic converter, and a muffler all items requiring service, and all items that aren't needed in an electric car.

The Tesla Roadster's elegantly designed powertrain consists of just the four main components discussed below. Mind you, these aren't "off-the-shelf" components, and each includes innovations, both small and large. But when you build a car from the ground up, you have the luxury of questioning every assumption and to distill as you reinvent.

The Energy Storage System (ESS)

When we set out to build a high-performance electric car, the biggest challenge was obvious from the start: the battery. Its complexities are clear: it's heavy, expensive, and offers limited power and range. Yet it has one quality that eclipses these disadvantages and motivated us to keep working tirelessly: it's clean.

The Tesla Roadster's battery pack the car's "fuel tank" represents the biggest innovation in the Tesla Roadster and is one of the largest and most advanced battery packs in the world. We've combined basic proven lithium ion battery technology with our own unique battery pack design to provide multiple layers of safety. It's light, durable, recyclable, and it is capable of delivering enough power to accelerate the Tesla Roadster from 0 to 60 mph in under 4 seconds. Meanwhile, the battery stores enough energy for the vehicle to travel more about 245 miles (EPA city/highway) without recharging, something no other production electric vehicle in history can claim.

Motor

Some people find it hard to imagine our car's Lamborghini-beating acceleration comes from a motor about the size of a watermelon. And while most car engines have to be moved with winches or forklifts, ours weighs about 70 pounds a strong person could carry it around in a backpack (although we don't recommend it). Compare that to the mass of machinery under the hood of $300,000 supercars that still can't accelerate as quickly as the Tesla Roadster.

But more important than the motor's size or weight is its efficency. Without proper efficiency, a motor will convert electrical energy into heat instead of rotational energy. So we designed our motor to have efficiencies of 85 to 95 percent; this way the precious stored energy of the battery pack ends up propelling you down the road instead of just heating up the trunk.

Transmission

Our transmission couples the fuel efficiency of a manual with the driving ease of an automatic. The Tesla Roadster has only two forward gears, allowing you to fine-tune your driving experience (but either gear will work for most driving scenarios). Unlike a manual transmission, the car will not stall if you have it in the wrong gear. There's also no clutch pedal. Just move the lever and the electronic control module takes care of the shift, so you can launch from a full stop to freeway speed without taking your focus off the road, your foot off the accelerator, or your hands off the wheel.

Power Electronics Module (PEM)

Most of the subsystems in the Tesla Roadster are completely electronic and under direct software control. But unlike all other cars, these systems are not a hodge-podge of independent systems instead, they are designed as an integrated system, the way complex network and computer systems are designed today.

You'll see the hub of this network every time you pop the trunk the Power Electronics Module. When you shift gears or accelerate in the Tesla Roadster, the PEM translates your commands into precisely timed voltages, telling the motor to respond with the proper speed and direction of rotation. The PEM also controls motor torque, charging, and regenerative braking, and it monitors things like the voltage delivered by the ESS, the speed of rotation of the motor, and the temperatures of the motor and power electronics.

The PEM controls over 200 kW of electrical power during peak acceleration enough power to illuminate 2,000 incandescent light bulbs.