General Motors said
yesterday it is coming closer to having a production version of the lithium-ion
battery for its high-profile Chevy
Volt vehicle, but added that quality, reliability and durability testing
remains.
GM's
comments came after its ceremonial unveiling of the Volt production car at its
headquarters in Detroit's Renaissance Center.
The Volt, scheduled for production launch in late 2010, is considered critical
to the future of GM and the auto industry because it combines an all-electric
powertrain with the extended range of a gasoline-burning vehicle. Yesterday's
unveiling reinforced GM's commitment to the car and enabled news media to view
its exterior and interior.
GM told
Design News, however, that the Volt's key technology – its lithium-ion battery –
is still under development.
"The
battery is definitely the area of greatest challenge," said Denise Gray,
director of Global Battery Engineering for GM. "Over time, a battery's capacity
decreases. There are accelerated (life) tests that we still have to confirm as
time goes on."
GM
engineers have previously acknowledged they are concerned about quality,
reliability and durability issues related to the lithium-ion battery.
Ordinarily, they would perform about three to four years of testing to get a
good handle on those issues, but the Volt's accelerated schedule won't allow
for that.
Gray said the giant automaker is currently testing the vehicle's battery packs and
its individual lithium-ion cells. Some of the testing is taking place in
laboratories, some is being conducted at supplier sites and some battery cells
are being tested in vehicles, she said.
"The goal
of my program is to get as much design and test experience as possible," Gray
said. "That's how you learn; it's how you get to know your parts better."
GM said it
plans to use about 220 of the flat lithium-ion cells, each of which measures
about 4 X 3.5 inches. Cells are integrated into battery packs that include
multiple microcontrollers, cabling and a liquid-cooling system. Liquid cooling
helps keep the temperature of the lithium-ion cells "in the sweet spot," Gray
said.
GM would
not yet say whether battery manufacturers are coming close to the cost goals
set by the United States Advanced battery Consortium (USABC) for 40-mile
electric range vehicles. Earlier this year, the USABC told Design News its cost
goal for the batteries was $293/kW-hr. Most observers believe today's
lithium-ion battery packs don't yet come close to those goals.
Two
supplier teams are currently working on the development of the cells and
battery packs for the Volt. One team consists of LG Chem, which hopes to manufacture the
lithium-ion cells, and Compact Power,
Inc., a maker of battery packs. The other team consists of lithium-ion cell
manufacturer A123 Systems and
automotive systems integrator Continental
Automotive. GM said yesterday only one team would be chosen to make
the production batteries and it doesn't yet know which team that will be.
"We are still testing
and refining and having lots of meetings with those manufacturers," Gray said.
"But we will definitely choose only of the two teams for 2010."
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