The Audi e-tron concept electric car

(AP) -- Ford Motor Co. and Microsoft Corp. have signed a deal to work together on a computerized link between houses, electric cars and utility companies to help manage energy use.

The companies said Wednesday at the New York International Auto Show that this is the beginning of a smart system that will help utilities and customers manage energy costs and electrical generating capacity.

The system would start with the all-electric Ford Focus compact car that is scheduled to go on sale late in 2011. Called "Microsoft Hohm," it will allow utilities to vary electric rates based on the time of day. A computer would determine the best time to recharge the car at the lowest cost and the least burden on the utility's generating system.

Charging an electric car can double the energy used at a home, and utilities worry about the increased burden on their power generators. But charging the cars late at night, when appliances and other big electricity users aren't working, can help manage the load.

The companies have time to work out details of exactly how the system will work, figuring out electric rates and loads on generating systems, said Derrick Kuzak, Ford's global product development chief. Microsoft already has computer nodes for home thermostats and appliances to manage electricity use, he said.

"We're doing a lot to bring vehicles to market, but there has to be a lot of other work done from both a consumer and utility perspective to make this viable and affordable," Kuzak said Wednesday in an interview.

The system eventually will lead to homeowners being able to use their cars to power home appliances and cut costs at peak electricity use times, Ford CEO Alan Mulally said Wednesday.

"As the batteries get more capable, we'll be able to store the electricity and then actually start to move the electricity around to where you really need it," he said.

Ford says the software to charge the cars will be included at no additional cost.

Ford and Microsoft are not the first to start such an effort. Many utilities and other companies have been working on "smart home" technology for several years.

In 2008, General Motors Corp. joined with more than 30 utility companies across the U.S. to help work out electric use issues when rechargeable cars start showing up in large numbers. GM plans to begin selling the Chevrolet Volt rechargeable car in late 2010.

Besides the electric Focus, Ford plans to begin selling an all-electric Transit Connect small commercial van this year. Its plans include offering a total of five new electric or gas-electric hybrid vehicles in North America and Europe by 2013.

Ford shares were down 58 cents, or 4.4 percent, to $12.70 in afternoon trading. Microsoft shares fell 30 cents to $29.47.

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