Probe of Chevy Volt Fires Closed

The government on Friday closed its investigation of Chevy Volt battery fires, concluding that there is no defect trend and that electric cars do not pose a greater risk of fire than gasoline-powered vehicles.

The National Highway Traffic Safety Administration also said that it was satisfied with a plan by General Motors to address problems that triggered fires in Volts after crash tests.

"Generally all vehicles have some risk of fire in the event of a serious crash," NHTSA said in closing the two-month investigation.

No real-world fires were reported by regulators or the automaker, but the investigation has cast a shadow over GM's heavily promoted bid to lead on fuel efficiency and green technology with the Volt.

NHTSA opened its investigation after separate fires last year.

A battery pack in a Volt crash tested in May caught fire three weeks later at a NHTSA facility. In lab tests completed in late November, a second Volt pack began to smoke and throw off sparks, while a third battery pack caught fire a week after a simulated crash.

In response to the safety concerns, GM has said it will strengthen structural protection for the 400-pound lithium-ion battery in the Volt, and take other steps to prevent coolant fluid from leaking and triggering a fire.

The automaker said in a statement on Friday that NHTSA's decision is consistent with the results of its own analysis