PALO ALTO, Calif--During a tour of Tesla's headquarters, a big, black slab caught our attention. It was sitting in a thermal testing station that would put it through a range of temperatures from -104 degrees all the way up to 122 degree Fahrenheit. This slab is the battery pack for the upcoming Tesla Model S.
Tesla's first production car, the Roadster, had a boxy shaped battery pack designed to fit right behind the seats of a Lotus Elise, the chassis that Tesla uses for the Roadster. As the Model S was designed and will be built by Tesla, the company had a lot more leeway on how it formatted the battery.
Tesla decided to package it in the floor of the car, contributing to the vehicle's handling by keeping its center of gravity low. Tesla has not specified how much the Model S' battery pack weighs, but it looked bigger than that in the Roadster, which comes in at close to 1,000 pounds. To our quick eyeballing of the Model S battery pack size, we're guessing at 7 feet long, 4 feet wide, and 6 inches thick.
Similar to the Roadster, the Model S battery pack is filled with cylindrical lithium ion cells dubbed 18650s. Tesla does extensive testing of these cells at its headquarters, cycling them at different temperatures, trying different discharge rates, and even crushing them. The data Tesla collects gets used to refine the specifications sent to its suppliers, among them Panasonic and Samsung. … Read more