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GM to Test Lithium-Ion Batteries for Chevy Volt
Automaker says Volt is still on time for 2010 launch
Charles J. Murray, Senior Technical Editor -- Design News, June 22, 2008
Read more about the engineering behind the Chevy Volt on our !
General Motors’ highest priority technology will reach the proving grounds this month as engineers test the lithium-ion battery for the Chevy Volt.
A GM spokesman said yesterday a six-ft-long, 375-lb, T-shaped battery pack has been placed aboard an engineering development vehicle known as a “mule.” Engineers are currently testing the mule in a lab setting and plan to move it outdoors to the company’s Milford Proving Grounds test track later this month.
The announcement is considered a major step forward for GM and its plug-in hybrid program because the existence of testing implies the vehicle’s official launch is still on time. The Volt is currently set for a 2010 launch.
“The news that the battery is going into a mule is being viewed by many people as a major milestone,” a GM spokesman said yesterday.
The new battery is designed to provide the Volt with a 40-mile pure electric range. Known as a “plug-in hybrid,” the Volt will use the battery to power electric motors that drive its front wheels. GM has said the Volt will use an engine-generator set to recharge its lithium-ion battery beyond the initial 40 miles.
Lithium-ion is considered the battery of choice for the coming generation of plug-in hybrids because it packs greater energy density than lead-acid or other battery alternatives.
Work still remains to be carried out on the technology, however, mainly in the areas of reliability, durability and cost. To do the necessary testing, GM engineers placed the battery pack aboard the mule, which consists of an old Chevy Malibu with an opening carved into the floor.
GM said it will test two types of battery packs at the proving grounds: a lithium-ion version from Continental Automotive Systems and A123 Systems and another from Compact Power, Inc. and LG Chem. The A123 cell employs a “nano-phosphate” cathode, while LG Chem uses a manganese-spinel chemistry.
With either chemistry, GM engineers have said their foremost concern is the industry’s lack of experience with the technology. Although lithium-ion has been used in cell phones and laptop computers, engineers don’t yet know how the technology will perform in an automotive setting. Ideally, GM engineers would like to have at least three years to track lithium-ion’s performance, but the 2010 launch date doesn’t permit such a long testing period. To make the launch date, battery packs must be ready this year.
Battery experts have questioned whether lithium-ion EV batteries are ready today. “It depends on your definition of the word ‘ready,’” says Elton Cairns, an emeritus professor of chemical engineering at the University of California Berkeley and a former battery scientist at GM and NASA. “If you ask, ‘Can it be done?’ The answer is yes. If you ask, ‘Will it be affordable by today’s consumers?’ The answer is no.”
