High Performance Energy Storage System Is Key Driver For Tesla Roadster

SAN CARLOS, Calif. (July 19, 2006) — What has 6,831 non-moving parts and powers a car? It's the unique Energy Storage System of the new Tesla Roadster.

The 6,831 non-moving parts are cells slightly larger than a typical AA battery. The large number of small cells allows Tesla Motors's engineers to create an energy storage system around fixed points on the chassis, ensuring optimum efficiency in packaging.

Tesla Motors CTO JB Straubel said, "Maximizing battery run-time is critical for an electric vehicle, but we've been able to do just that with the Tesla Roadster while minimizing weight and maximizing safety. The proprietary technology developed at Tesla Motors for our Energy Storage System is critical to the success of the Tesla Roadster."

The Energy Storage System (ESS) provides power to the entire vehicle, including the motor. It comprises a durable and tamper-resistant enclosure, the 6,831 cells, mechanical structure to mount the batteries, electrical interconnection between the cells, interconnection to the power electronics unit, a network of microprocessors for maintaining charge balance and temperature monitoring, a cooling system, and an independent safety system that is designed to isolate high voltage outside the enclosure under a variety of detectable safety situations.

A cooling system is controlled by the vehicle electronics. It uses a secondary loop in the cabin air conditioning system to provide chilled coolant which is circulated throughout the ESS. A resistive heater is used to heat the batteries in extreme cold conditions.

Batteries using the same lithium-ion technology used in Tesla Motors's vehicles have proven themselves over years of usage in modern electronic devices such as cell phones, camcorders, MP3 players and other digital devices. Unlike previous-generation nickel-cadmium and nickel-metal-hydride batteries, lithium-ion batteries have no "memory," and are good for 500 complete charge/discharge cycles before replacement may be required.

Lithium-ion cells are rechargeable and provide one of the best energy-to-weight ratios and a slow loss of charge when not in use. Pioneered by Gilbert N. Lewis in 1912, the first commercially available lithium-ion cell was created by Sony in 1991.

Lithium-ion technology is improving rapidly with the latest breakthroughs focusing on reducing charging time, and improving the capacity of cells. Tesla Motors continues to explore improvements in energy storage technologies and is actively working with several lithium-ion cell manufacturers.

About Tesla Motors

Tesla Motors was founded in July 2003 by Martin Eberhard and Marc Tarpenning to create efficient electric cars for people who love to drive. The chairman of Tesla Motors, a privately held company, is Elon Musk, who has led or co-led all three rounds of investment resulting in $60 million in funding. Mr. Musk has been instrumental in both corporate and product development at Tesla Motors.

The company currently employs over 80 people, including teams in California, the U.K. and Taiwan. The background and experience of Tesla Motors's employees mirrors the vehicle itself, drawing from diverse expertise in the electronics, automotive and software industries.

Tesla Motors creates vehicles that conform to all U.S. safety, environmental and durability standards. Tesla Motors's cars include modern safety equipment such as airbags, front crumple zones, side impact protection, and 2½ mph bumpers. Tesla Motors will only sell cars in the U.S. when they pass the Federal Motor Vehicle Safety Standard (FMVSS).

For more information, visit www.teslamotors.com.