As hybrid and electric vehicles get nearer to production, the focus on lithium-ion batteries is starting to shift from safety to affordability.

During a panel discussion at a plug-in vehicle conference in Detroit, several speakers said dramatic cost cuts are possible once the advanced batteries reach high-volume production.

No concerns were expressed about the safety of the advanced batteries, which in the past have overheated and started fires in consumer electronics.

Johnson Controls-Saft Advanced Battery Systems aims to reduce the cost of a lithium-ion battery pack by 50 per cent, said Michael Andrew, the venture's director of government affairs and external communications for hybrid electric battery systems.

He said JCI-Saft is not just looking at the cost of materials that go into the batteries but the way the cells are manufactured.

He said battery makers can learn from other industries how to produce lithium-ion cells more efficiently.

"We have an opportunity here to revolutionise the way these cells are built," Andrew said.

"We think we can leverage process technology being used in other industries to rapidly bring down the cost."

JCI's goal, he said, is to make a battery pack for a hybrid or an electric car that will cost the consumer the same as a petrol engine over three years.

Nissan's plan to lower costs for the 2012 Leaf electric car involves manufacturing the batteries and assembling the cells into packs at the plant where the car will be built, said Mark Swenson, Nissan North America's vice president of manufacturing engineering and vehicle production engineering.

"We plan to run the plant around the clock to maximise our investment in the production equipment," Swenson said.

The Leaf, he said, will be just one of several electric vehicles Nissan plans to sell in North America.

Ric Fulop, vice-president of business development for A123 Systems Inc, said he believes the cost of battery packs could come down 9 per cent per year as the industry matures.

Some savings would come from making batteries more powerful, while other costs could be cut by refining the production process and using higher-quality materials.

Ravi Ramanathan, director of global business development for the Dow Chemical Co, said battery costs can also be reduced by making them more powerful and efficient, and by controlling quality during production.

Car manufacturers won't talk about how much the battery packs for hybrids and electric vehicles cost. But some estimates place the cost of the lithium-ion batteries for the Chevrolet Volt at around US$8000 ($10,600).