Japanese auto and battery makers are working to set international technical standards for lithium-ion batteries, a move that could give the companies an advantage over their competitors in the United States and Europe.

Toyota Motor, Nissan, Matsushita Electric Industrial and more than a dozen other vehicle and battery manufacturers plan to propose technical specifications for standards – which would regulate charging methods, vehicle safety and other aspects of the technology – to the International Organization for Standards, according to the Nikkei, a Japanese business daily.

The news came out just as two automotive conferences in the United States and the United Kingdom are set to begin. Plug-In 2008 officially begins in San Jose, Calif., on Tuesday, while the British International Motor Show is scheduled to begin in London on Wednesday.

Lithium-ion batteries are commonly used in consumer electronics such as laptops and cell phones, but their potential for storing a large amount of electricity in a compact shell has made them attractive candidates for charging plug-in hybrid and all-electric cars.

Toyota said last month that its joint venture with Matsushita, called Panasonic EV Energy, would start a full-scale production of lithium-ion batteries in 2010 (see Toyota Drives Towards Greener Fleet). Toyota currently uses nickel-metal hydride batteries for its Prius. Other Japanese automakers have also partnered with battery makers to develop car-worthy lithium-ion batteries.

Setting technical standards would enable car and battery makers to cut development and manufacturing costs. But reaching a consensus on those standards could be a contentious process, as companies wage battles over which technologies should be included.

Aside from the Japanese group, for instance, American car companies are working on their own plans for developing battery standards.

General Motors, Ford Motor and Chrysler are participating in joint research on batteries and hydrogen fuel cells through the private United States Council for Automotive Research (USCAR). A USCAR group, called United States Advanced Battery Consortium, received a $6.5 million grant from the U.S. Department of Energy last September to develop lithium-ion battery technology for hybrid-electric cars.

“Ford, in addition to other domestic car makers, is working with the DOE to advance battery research. Part of the research is to learn more about the lithium-ion battery technology and [to] work toward setting industry standards,” said Alan Hall, a Ford spokesman.

The battle over tech specs would affect, not just carmakers, but also other public and startups that already have poured in millions into technology development.

A123 Systems, a lithium-ion startup in Watertown, Mass., is under contract to sell its products to Norwegian electric-car company Think Global (see Think Global to Bring Electric Crossover to the U.S.).

Think will debut a two-seater all-electric car, Think City, at the British International Motor Show this week. The carmaker also plans to introduce a five-seat sedan, called Think Ox, to the U.S. market as early as 2010.

Valence Technology (NSDQ: VLNC) in Austin, Texas unveiled a new lithium-ion battery system for the car market last November (see Batteries Key to Plugging In at Electric Vehicle Symposium).

Meanwhile, General Motors and utilities plan to announce a partnership to popularize plug-in hybrid cars this week, Reuters reported. GM also is set to unveil a production version of its hybrid Chevy Volt, which the company expects to launch in 2010 (see Chevy Volt Cleared for 2010 Production).

And ICP Solar Technologies in Montreal, Canada, said Monday it has signed a deal to supply Nissan with dashboard-mountedsolarchargers for the North American and European markets. The chargers would keep batteries in new cars fully charged as the cars sit in the dealership lots, waiting for buyers.