Electric vehicles and hybrids pose special hazards in a crash test. Here’s how the nation’s top testing Institute prepares for the worst.
Crashing 4,000 pounds of steel and aluminum into a rigid barrier at 40 MPH is destructive enough. The kinetic energy is immense. However, crash testing also involves a serious risk of fire or explosion that must be carefully managed. To ensure the safety of its engineers and technicians, the Insurance Institute For Highway Safety (IIHS) takes special precautions to reduce the chance that a conventional liquid-fuel vehicle doesn’t go “poof!” after the “bang!” Interestingly, IIHS is more concerned about the risk of fire from electric vehicles and hybrids than from gasoline-powered vehicles.
IIHS is wise to be worried. The National Fire Protection Agency (NFPA) knows that all well-trained first responders and fire fighters are prepared for the 172,000 gas and diesel vehicle fires they deal with each year. To ensure that those men and women are ready to meet the challenges of an electrified vehicle fire, the NFPA began working with the U.S. Department of Energy in 2009 to develop best practices and special tactics for fighting vehicle battery fires.
BestRide reached out to IIHS spokesperson, Russ Rader to find out what IIHS does differently when the vehicle being smashed has a high-energy lithium ion or nickel metal hydride battery onboard. Russ told us, “Similar to the way we use Stoddard fluid to reduce the risk of fire with conventional vehicles, we test electric vehicles at a reduced state of charge to reduce the risk of thermal runaway if the electrical system is damaged.”
Thermal runaway is no small matter. The energy released can be intense and the fire hard to extinguish. See time stamp 10 minutes in the video above. Rader explained, saying, “Since thermal runaway can happen quickly, we are prepared to immediately evacuate the vehicle from the crash hall if we detect smoke or fire. As an added precaution, the fire department is also always present at the Vehicle Research Center during tests of electric vehicles or hybrids.” One final step IIHS does for hybrid and electric vehicles is to move the vehicles away from the test center as soon as possible. Rader says, “We store vehicles after crash tests until results are released publicly. While conventional vehicles are usually kept inside the building after testing, we isolate electric vehicles in an area outdoors away from the building.”
In a gas or diesel vehicle crash test any fuel leak is an automatic “Poor” rating on the test. Likewise, any damage to the high-voltage system in an EV results in an automatic “Poor.” Tesla’s Model S came close to receiving this score when it underwent a re-test of the small frontal overlap test. The Model S had scored just “Acceptable,” disqualifying it from the top score, while many cars its size, and at much lower price points, had scored “Good.” The second test didn’t help Tesla’s score, but uncovered a potentially bigger issue. The left front corner of the battery compartment suffered damage in the crash. IIHS’ report noted, “The deformation was limited to an area that didn’t contain battery cells in the tested vehicle, so this damage didn’t affect the rating.” The Model S has a variety of battery sizes, and the one tested was of the smaller type. If the Model S IIHS tested had contained the additional cells, the result of the test would have been a “Poor” rating.
In the event of an electric vehicle fire, NFPA details special steps for firefighters, and even prints booklets showing the special “no-cut” and other caution areas of individual EVs. NFPA’s special instructions for handling all EV fires include preparing more water for the fire than a conventional car fire, not trying to pierce the battery case in order to access the fire’s source, and taking longer to ensure the fire won’t re-ignite after it is extinguished.