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| GM puts plug-in Volt to the test | |
4 April 2008 |
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GM engineers in Germany and the US are testing the durability of the Li-ion batteries for the OEM’s Chevrolet Volt plug-in hybrid vehicle. Wind tunnel work is underway too. The battery cycling equipment is working around the clock in GM’s test facilities in the US and Mainz-Kastel, Germany. It charges and discharges power from the prototype cells based on the Volt’s 64km electric-only drive cycle. Results help predict the battery’s durability.
GM said the batteries will soon be integrated into mule vehicles with other electric-drive components for on-road tests. “The conditions in a vehicle – where the battery is exposed to shaking, moisture and rapidly changing temperature conditions – are much more extreme than the controlled settings of the lab,” said Weber. Engineering an electric vehicle with a battery roughly 1.8 m long and weighing more than 170 kg is not easy. GM is treating it as part of the vehicle structure: the T-shaped cell will sit in the car’s centre tunnel of the vehicle and under the rear seats. Weber said: “It’s an integral part of the vehicle that interacts with the thermal and safety systems and chassis components.” Aerodynamic drag accounts for around 20 per cent of the energy consumed by an average vehicle. GM’s aerodynamics lab in Warren, Michigan is working on the airflow. The project began with a 1/3-scale model to define the basic shape and the main features. The model included a detailed underbody and engine compartment, although GM used computational fluid dynamic models for the radiator and under-hood cooling flow. GM global design vice-president Ed Welburn said: “After extensive aerodynamic testing, the Volt has a drag coefficient that is 30 per cent lower than the original concept.” The OEM did not give a specific figure, however.
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