DETROIT (Bloomberg) -- U.S. auto-safety regulators are scrutinizing the safety of lithium ion batteries that power electric vehicles after a Chevrolet Volt battery caught fire, people familiar with the probe said.
The regulators have approached all automakers, including General Motors, Nissan Motor Co. and Ford Motor Co., that sell or have plans to sell vehicles with lithium ion batteries with questions about the batteries' fire risk, four people familiar with the inquiry said.
The Volt caught fire while parked at a National Highway Traffic Safety Administration testing center in Wisconsin, three weeks after a side-impact crash test, said an agency official.
The official, as well as the three other people familiar with the inquiry, said they couldn't be named because the investigation isn't public.
“I want to make this very clear: the Volt is a safe car,” said Jim Federico, GM’s chief engineer for electric vehicles. “We are working cooperatively with NHTSA as it completes its investigation. However, NHTSA has stated that based on available data, there’s no greater risk of fire with a Volt than a traditional gas-powered car.”
The probe comes as automakers look to expand plug-in offerings beyond the Volt and Nissan's Leaf, which went on sale in the 2011 model year as the first mass-market plug-in electric cars in the United States.
Toyota Motor Co.'s Prius, the world's best-selling hybrid, uses a nickel-metal battery. A plug-in Prius and an electric version of the RAV4 sport-utility vehicle will use lithium ion batteries.
President Barack Obama has set a goal of putting 1 million electric vehicles on U.S. roads by 2015. Nissan is among companies that have received financing assistance from the U.S. Energy Department and European Investment Bank to develop the Leaf and lithium ion batteries.
GM in January withdrew a request for $14.4 billion in U.S. loan guarantees.
Seoul-based LG Chem Ltd., South Korea's biggest chemical maker, supplies the lithium ion batteries for the Volt.
Concern for first responders
The fire was severe enough to burn vehicles parked near the Volt, the agency official said. Investigators determined the battery was the source of the fire, the official said.
NHTSA also sent a team of investigators this week to Mooresville, N.C., to probe a fire in a residential garage where a Volt was charging. That investigation is continuing, the agency official said.
"As manufacturers continue to develop vehicles of any kind -- electric, gasoline, or diesel -- it is critical that they take the necessary steps to ensure the safety of drivers and first responders both during and after a crash," the safety agency said in a statement today.
"Based on the available data, NHTSA does not believe the Volt or other electric vehicles are at a greater risk of fire than gasoline-powered vehicles. In fact, all vehicles -- both electric and gasoline-powered -- have some risk of fire in the event of a serious crash."
The agency's greater concern is for rescue response teams, tow truck operators and salvage yards who may be storing plug-in cars after an accident, the official said.
GM spokesman Greg Martin said the company doesn't believe the Volt poses any greater risk to drivers than a conventional automobile. GM has spent almost 300,000 hours testing the car and believes it is safe, he said.
After the fire in June, GM and NHTSA both crashed a Volt and could not replicate the fire, Martin said. GM has safety protocols for handling the Volt and its battery after an accident. Had those been followed, there wouldn't have been a fire, Martin said.
"There are safety protocols for conventional cars," Martin said. "As we develop new technology, we need to ensure that safety protocols match the technology."
The Volt and Leaf went on sale in late 2010. U.S. sales of the Volt have reached 5,003 units this year through October; Leaf sales total 8,048 units.
Nissan spokeswoman Katherine Zachary said today there have been no incidents of fire involving the battery in the Leaf.
"The Nissan Leaf battery pack has been designed with multiple safety systems in place to help ensure its safety in the real world. All of our systems have been thoroughly tested to ensure real-world performance," Zachary said. "To date, the more than 8,000 Nissan Leafs driving on the U.S. roads have performed without reported incident."
Automakers have engineered electric vehicles using lithium ion batteries to withstand serious accidents because the element is flammable, said Sandy Munro, president of Munro and Associates, an engineering consulting firm in Troy, Mich.
Lithium ion batteries could catch on fire if the battery case and some of the internal cells that store electricity are pierced by steel or another ferrous metal, he said.
"Lithium burns really hot," Munro said. "But it doesn't happen often. You have to do something pretty dramatic to make it catch fire."
If a lithium ion battery is pierced by steel, a chemical reaction will take place that starts raising the temperature and can result in a fire, he said. If the piercing is small, that reaction can take days or weeks to occur, he said.
NHTSA this year gave the Leaf and Volt its top crash-test safety rating, following a "good" rating in April by the Insurance Institute for Highway Safety.
In the simulated side-impact crash test, a new U.S. safety test for the 2011 model year, metal punctured the battery, the official said.
Regulators want to use information collected from automakers to inform emergency responders, towing firms and salvage yards about how to handle plug-in electric cars involved in crashes that may penetrate the battery compartment, the official said.
NHTSA will use the information from the automakers, which also include Toyota and BMW AG, for a three-year $8.8 million electric-vehicle safety study it announced in June, the official said.
The Federal Aviation Administration, in an advisory to airlines in October 2010, warned that lithium batteries used in cell phones, digital cameras and other devices are "highly flammable and capable of ignition," adding that fire suppression systems aren't effective when that happens.
It issued the advisory after a United Parcel Service Inc. cargo plane carrying thousands of lithium batteries crashed in Dubai after catching fire, killing both pilots.
Fifteen electric-car or battery-powered models will be available in the United States by the end of 2014, according to J.D. Power & Associates, which forecasts a glut of electric cars given that hybrid-electric sales were only 2 percent of the car market so far this year.
Lindsay Chappell and David Phillips contributed to this report