Mercedes sees electric-car progress

Mercedes-Benz says it will have a demonstration fleet of practical, if small, electric vehicles on the road in two to three years.

They're expected to run 80 miles or more on lithium-ion batteries the German automaker is developing. Regular production could begin a few years later.

The announcement follows its declaration earlier this month that it will be first in the U.S. market with a gasoline-electric hybrid using a lithium battery pack.

Together they suggest significant progress in lithium battery development — a breakthrough, Mercedes unabashedly says.

Lithium batteries, common in cellphones and laptop computers, are significantly more powerful for their size and weight than other types of batteries. But scaling up for auto use introduces new challenges.

Low-cost, long-life lithium batteries are seen as essential for accelerated development of alternative-power vehicles, ranging from the now-familiar gasoline-electric hybrids that double normal fuel economy to hydrogen fuel-cell vehicles that use no petroleum.

As automakers compete to make such models more practical, using their own interpretations of Mercedes' backpack-size lithium battery, costs should drop. That would mean you might be able, sooner and cheaper than expected, to buy a car that gets extraordinary mileage, and perhaps directly uses no gasoline at all.

The first-to-market Mercedes hybrid using lithium-ion batteries will be a gasoline-electric version of its S-class sedan in 2009. Its V-6 gasoline engine, helped by an electric motor, will feel like a V-8 but use less fuel.

A key hurdle to using auto-scale lithium batteries is that they require careful temperature management and monitoring of the charge in each individual cell.

Mercedes says it has solved those issues for the hybrid batteries and hopes to say the same soon for a different version needed for its pure electric car based on its Smart brand of tiny two-seaters.

"Our plan in the next two to three years is to have a test fleet of Smart electric vehicles," Mercedes engineer and Vice President Herbert Kohler, who heads advanced powertrain operations, said in an interview at the auto show here. He said it would take several years to be sure the setup is right for mass production.

"To show a demonstration fleet is easy. To do series production is a different matter," says Thomas Weber, member of the Mercedes board of management who's in charge of research and development.

Even though Mercedes expects to be first with hybrids using lithium-ion batteries, General Motors aims to be first to field a showroom-ready pure electric vehicle using lithium. Its Chevrolet Volt two-seater is planned for late 2010 or 2011, priced about $35,000.

Unlike gas-electric hybrids, electric cars such as Volt and the Smart will be propelled entirely by an electric motor running on batteries. They can be recharged by plugging into an outlet for six hours or more.

Plug-in hybrid electric vehicles (PHEVs) — still in the prototype stage and not on sale — would bridge the gap, running on battery power at least a few miles before requiring help from the gasoline engine.

Lithium batteries' extra storage capacity would allow PHEVs to go farther before needing help from their gasoline engines. PHEVs, like electric cars, can be recharged by plugging into an electric outlet.

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