Credit to the Tesla Web site for this Info: www.teslamotors.com 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. 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 Battery 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 available and 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 about 220 miles without recharging, something no other production electric vehicle in history can claim. Motor Some people find it hard to imagine our car's supercar-level 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 115 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 single-speed gearbox couples the low drag and fuel efficiency of a manual transmission with the driving ease of an automatic. The Tesla Roadster has only one forward speed. That speed is quick. How fast quick arrives is up to the driver. Perfectly modulated velocity is under total control at all times. There is no clutch pedal. Just move the shift lever and the Power Electronics Module takes care of everything. You can launch from full stop to highway speed without taking your focus off the road, your foot off the accelerator, your hands off the wheel, or your mind off an entirely new kind of driving experience. Power Electronics Module (PEM) Most of the subsystems in the Tesla Roadster are completely electronic and under direct software control. Unlike lesser cars, these systems are not merely a hodge-podge of independent systems arranged pell mell. Instead, each component is designed to be part of a whole that is based on the modern architecture of complex network and computer systems. You'll see the hub of this network every time you pop the trunk — the Power Electronics Module (PEM). 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 Battery, 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.