Volt to carry 8-year battery warranty

The guarantee is better than warranties on GM's conventional car engines and transmissions, which are five years or 100,000 miles.

The rechargeable Volt is due in showrooms this November. The vehicle can travel 40 miles on battery power before a small gasoline engine takes over to generate power so the car can go longer distances. The Volt is expected to be priced around $35,000 but will probably cost less after federal tax credits.

A longer warranty will help GM as it tries to convince people to adopt the new lithium-ion battery technology.

Tom Stephens, GM's vice chairman of product planning, said the automaker is confident that the batteries will be problem free for longer than the warranty, although their ability to hold charges will decline slightly over time.

"Originally when we were looking at this, we wanted to make sure that the batteries were good for more like 10 years," he said.

The batteries have a similar chemical composition to those in cell phones and computers. Those batteries often wear out in a few years and are relatively expensive to replace. Early on GM had pegged the cost of a 400-pound Volt battery at around $10,000, the most expensive single component in the car.

Costs should drop as GM sells more Volts, and should be substantially lower after eight years, Stephens said. He said used batteries can be shipped to GM to be rebuilt to extend their lives. Customers also would have the option of disposing of them, he said.

Mickey Bly, GM's executive director of electrical systems, said battery cost has dropped substantially as GM learns more about the new technology and because of government funding that has reduced development costs. He would not give a figure on how far the cost has dropped.

The Volt warranty also covers the battery cooling and heating systems, its charging system and the electric drive components, GM said.

The Volt will first go on sale in Texas, New York, New Jersey, Connecticut, Michigan, California and Washington, D.C. The automaker plans to produce 10,000 by the end of 2011 and an additional 30,000 in 2012.

Other automakers are rolling out electric cars. Shortly after the Volt goes on sale, Nissan Motor Co. will begin selling the Leaf, which the company said will get up to 100 miles on a single charge. The Leaf will not have a gasoline engine, but will be cheaper than the Volt.

Nissan has not announced a battery warranty length for the Leaf.