Since that fire incident, NHTSA has taken a number of steps to gather additional information about the potential for fire in electric vehicles involved in a crash, including working with the Department of Energy and the Department of Defense—in close coordination with experts from General Motors—to complete rigorous tests of the Volt’s lithium-ion batteries.

During the week of 14 November, NHTSA performed follow-up battery-level tests to simulate the incident, intentionally damaging the battery compartment and rupturing the vehicle’s coolant line. Following a test on 16 November that did not result in a fire, a temporary increase in temperature was recorded in a test on 17 November. During the test conducted on 18 November using similar protocols, the battery pack was rotated within hours after it was impacted and began to smoke and emit sparks shortly after rotation to 180 degrees. NHTSA’s forensic analysis of the 18 November fire incident is continuing.

On Thursday (24 November), the battery pack that was tested on 17 November and that had been continually monitored since the test caught fire at the testing facility. The agency is currently working with DOE, DOD, and GM to assess the cause and implications of Thursday’s fire. In each of the battery tests conducted in the past two weeks, the Volt’s battery was impacted and rotated to simulate a real-world, side-impact collision into a narrow object such as a tree or a pole followed by a rollover.

Because of these test results, NHTSA said, it has opened this investigation to examine the potential risks involved from intrusion damage to the battery in the Chevrolet Volt, in coordination with the agency’s ongoing review of the emerging technology involved in electric vehicles.

NHTSA says it is not aware of any roadway crashes that have resulted in battery-related fires in Chevy Volts or other vehicles powered by lithium-ion batteries. Chevy Volt owners whose vehicles have not been in a serious crash do not have reason for concern.

In a statement, NHTSA said that while it is too soon to tell whether the investigation will lead to a recall of any vehicles or parts, if it identifies an unreasonable risk to safety, the agency will take immediate action to notify consumers and ensure that GM communicates with current vehicle owners.

NHTSA is continuing to work with all vehicle manufacturers to ensure they have appropriate post-crash protocols; asking automakers who currently have electric vehicles on the market or plan to introduce electric vehicles in the near future to provide guidance for discharging and handling their batteries along with any information they have for managing fire risks; and engaging the Department of Energy and the National Fire Protection Association to help inform the emergency response community of the potential for post-crash fires in electric vehicles.

NHTSA’s current guidance for responding to electric vehicles that have been in a crash remains the same. The agency continues to urge consumers, emergency responders, and the operators of tow trucks and storage facilities to take the following precautions in the event of a crash involving any electric vehicle:

• Consumers are advised to take the same actions they would in a crash involving a gasoline-powered vehicle—exit the vehicle safely or await the assistance of an emergency responder if they are unable to get out on their own, move a safe distance away from the vehicle, and notify the authorities of the crash.

• Emergency responders should check a vehicle for markings or other indications that it is electric-powered. If it is, they should exercise caution, per published guidelines, to avoid any possible electrical shock and should disconnect the battery from the vehicle circuits if possible.

• Emergency responders should also use copious amounts of water if fire is present or suspected and, keeping in mind that fire can occur for a considerable period after a crash, should proceed accordingly.

• Operators of tow trucks and vehicle storage facilities should ensure the damaged vehicle is kept in an open area instead of inside a garage or other enclosed building.

• Rather than attempt to discharge a propulsion battery, an emergency responder, tow truck operator, or storage facility manager should contact experts at the vehicle’s manufacturer on that subject.

• Vehicle owners should not store a severely damaged vehicle in a garage or near other vehicles.

• Consumers with questions about their electric vehicles should contact their local dealers.