There are certain things that one expects from a supercar; enough power to throw you back in the seat, a top-of-the-line stereo, tight cornering, and an enormous fuel bill. The Tesla Roadster has almost all of those things, except the last. It's very fast, very stylish, and corners like it's on rails- but there's one thing it lacks: the roar of the engine. The Tesla will never burn a drop of gasoline, as it is powered by an electric motor. It's powered by just four systems- the energy storage system, the power electronics module, an electric engine and a manual transmission.
Where the combustion engine would normally be, under the hood of the Tesla there is a bank of batteries (the ESS). When developing the Roadster's power source, Tesla went with that which was proven- the lithium ion battery, much like what is used in a laptop computer. The Roadster has 6,831 cells, weighing almost a half-ton. The cells are divided into sectors, and each of these is run by a processor which ensures that everything runs smoothly.
The PEM, or power electronics module, is a charging system that converts DC to AC using bipolar transistors. The result is more power than a traditional electric car; under top acceleration, the batteries can produce enough energy to illuminate 2000 light bulbs. Not only does the PEM control the charging/discharging of the batteries, it regulates voltage, engine RPMs, torque and regenerative braking. The latter takes the energy typically lost when braking and returns it to the ESS. The PEM, battery and other systems have an efficiency rating of 85-95%.
The Roadster can be charged in two ways; a charging system can be installed in your garage by an electrician, or you can buy a mobile kit that allows charging from any electrical outlet. A 220 volt, 70-amp outlet will allow the battery to charge fully in three and a half hours; the mobile kit is better suited to overnight charging.
Although car owners have driven around for years on top of tanks full of explosive gasoline, having a half-ton of batteries behind the cockpit gives some people a scare as well. Recent issues with the lithium-ion batteries in some laptops have accelerated those fears, but Tesla has taken a lot of time to address those concerns. The battery system was tested by heating individual cells until they caught fire; each is isolated enough to prevent damage to the one next to it in case of fire.