just-auto.com

US: GM's Volt on schedule - report

By just-auto.com editorial team | 15 May 2008

General Motors has test driven its Volt petrol-electric car for the first time on public roads and is meeting the target of 40 miles on pure electric power, according to a US report.

GM vice chairman Bob Lutz told Edmunds.coms' AutoObserver that the car ran on the street on battery power for the first time last Tuesday.

He said the Volt's powertrain, which combines a lithium-ion battery and a small petrol engine, was installed in a 'mule' test vehicle which is being driven on public roads around GM's proving grounds in Milford, Michigan.

"It is reliably meeting its objectives," Lutz told AutoObserver.com. "Even with a rough calibration, even with the wrong drive unit, the wrong body, etc etc, it has been hitting its 40 miles on electric power."

Tuesday's road test came after last week's testing of the Volt powertrain on a dynamometer that simulated real-world conditions, such as varying road surfaces and changing ambient temperatures, the report added.

AutoObserver.com noted that other automakers - including Renault-Nissan, Mitsubishi and Audi - had followed GM in developing the lithium-ion type of battery used in the Volt, in contrast to Toyota which is retaining nickel-metal hydride batteries for its next Prius hybrid, though it is known also to be working on the more advanced battery.

"The reason we point this out (others using lithium-ion) shows the fallibility of Toyota and the American press, which is totally enamoured with Toyota," Lutz told AutoObserver.com. "When we say lithium-ion is good and Toyota says they don't trust them and they are unproven, people say we're taking a huge risk."

Frank Weber, GM's global vehicle line executive and chief engineer of the E-Flex systems development team, told AutoObserver last August that the biggest challenge is to manage the thermal dynamics of the lithium-ion batteries so that the batteries are the same temperature.

Lutz reportedly insisted this week that the lithium-ion battery on the road has passed that test but would not say which supplier's battery is in the test mule - GM has development contracts with multiple battery makers.

According to AutoObserver.com, Lutz confirmed that in dynamometer tests last week of the Volt's lithium-ion batteries, engineers raised ambient temperatures and shut off the cooling system and the result was what GM had hoped - the battery showed only a slight rise in temperature and the heat was consistent across all of the battery cells with no pockets of intense heat.

"I can almost say the battery is the least of our problems," Lutz told AutoObserver.

He added that the challenge now is the smooth integration of the battery with the petrol engine that, unlike traditional hybrids that use a petrol engine to power the vehicle, starts only to generate electricity to feed the battery.

Lutz told AutoObserver.com the successful dynamometer and road tests increase GM's confidence that the Volt will be launched in November 2010.