Toyota powers on in battery race

Global automakers are racing to develop the next generation of energy-saving lithium-ion batteries, but Toyota has already been quietly using the technology in one of its cars in Japan — although in small numbers.

Worries about the safety of the batteries, which have had problems overheating and even bursting into flames, have been a major obstacle to introducing them in cars.

Lithium-ion batteries, already widely used in laptops and other gadgets, are considered critical in developing future electric, hybrid and other ecological vehicles because they are smaller and yet more powerful than the nickel-metal hydride batteries now used in hybrids like the Prius.

Since 2003, the lithium-ion battery has been part of an "intelligent package" for Toyota Motor Corp.'s Vitz subcompact — although the feature still isn't widespread among consumers. About 700 of the Vitz with the feature were sold this year.

Toyota Executive Vice President Masatami Takimoto said recently the company hasn't marketed the feature aggressively because battery supplies are limited and the company can't respond to massive demand.

But the feature is available at dealers, and consumers can get them if they ask.

"We don't tell everybody about it," Takimoto said. "But we already have our own lithium-ion battery."

Testing technology on public roads — especially over a long period of time — is crucial for ensuring the safety of a technology as well as for working out details of performance that may become a problem when an experimental technology is turned into a commercial product.

The Vitz with the lithium-ion battery — which sits beneath the passenger seat and recharges during driving — delivers better mileage at about 25 km a liter, compared with about 22 km a liter in the regular Vitz, according to Toyota.

Under the hood, the car also has a regular battery, which is used to start the engine.

When the car idles, as when the driver shifts to neutral or parks at a stoplight, the engine stops automatically without the driver having to switch off the ignition as in a regular car. That helps save on gas.

The engine restarts — powered by the lithium-ion battery — when the driver's foot is lifted from the brake pedal.

Other automakers, including General Motors Corp. of the U.S. and Nissan Motor Co., are all working on lithium-ion battery technology for green cars expected in the next decade or so.