US safety agency opens probe into Tesla fires (Update 2)

Nov 19, 2013 by Tom Krisher
In this Wednesday, Nov. 6, 2013 file photo provided by the Tennessee Highway Patrol, emergency workers respond to a fire on a Tesla Model S electric car in Smyrna, Tenn. The National Highway Traffic Administration has opened an investigation into battery fires in Tesla Model S electric cars. The probe affects more than 13,000 cars from the 2013 model year that were sold in the U.S. Tesla has sold about 19,000 of the cars worldwide. (AP Photo/Tennessee Highway Patrol, File)

The U.S. government's auto safety watchdog is investigating whether Tesla's Model S electric car is vulnerable to fires because roadway debris can pierce the car's underbody and battery.

The National Highway Traffic Administration, which announced the probe early Tuesday, is looking into two incidents in which Model S drivers struck metal objects on highways. The objects penetrated the bottom of the car, punctured the battery and caused fires.

Both drivers were warned of a problem by the car and escaped safely.

Tesla CEO Elon Musk said in a blog post that he requested the NHTSA investigation. He says accident data show that the Model S is far safer than gasoline-powered cars, but the probe is needed to dispel questions the public may have about the safety of electric vehicles as a result of the fires.

The probe affects more than 13,000 cars from the 2013 model year that were sold in the U.S. Tesla has sold about 19,000 of the cars worldwide. They start at $70,000 but often run more than $100,000.

Tesla's batteries are mounted beneath the passenger compartment and protected by a quarter-inch-thick (6 millimeters) metal shield. Experts say that if the batteries are damaged, that can cause arcing and sparks and touch off a fire.

NHTSA, in documents posted on its website, said it opened the preliminary evaluation "to examine the potential risks associated with undercarriage strikes" on the Tesla cars. The investigation could lead to a recall, but a decision likely is months away.

Musk, who has stated previously that the Model S won't be recalled, said Tuesday that if NHTSA discovers something "that would result in a material improvement in occupant fire safety," Tesla will make the change on new cars, as well as existing vehicles free of charge. He said such a discovery is "unlikely."

The low-slung Model S has a 6-inch (15-centimeter) clearance between the ground and the undercarriage. Other cars with gas engines sit lower, such as the Mercedes CLA Class at 3.9 inches (9.9 centimeters) and a Dodge Charger at 5 inches (12.5 centimeters), according to the Edmunds.com auto website. But the Tesla automatically lowers itself about another inch (2.5 centimeters) at highway speeds, the company's website said.

In his blog post, Musk wrote that Tesla has done an over-the-air software update to give the car more ground clearance at highway speeds. The change, Musk wrote, was made to cut the chances of underbody damage, not to improve safety.

"The theoretical probability of a fire injury is already vanishingly small, and the actual number to date is zero," he wrote.

Another software update in January will give the driver more control of the air suspension ride height, Musk wrote. The company also added fire damage to its warranty coverage "even if it's due to driver error."

According to the U.S. Fire Administration, there are around 194,000 vehicle fires on U.S. roads each year. The vast majority—61 percent—start in the engine area, while 15 percent start in the passenger area. Approximately 300 people die and 1,250 are injured in U.S. vehicle fires each year. Most happen in gas-powered cars, which make up the vast majority of cars on U.S. roads. Electric vehicles make up less than 1 percent of the cars sold in the U.S.

General Motors and Nissan make the top-selling battery-powered cars in the nation, the Volt and Leaf. Neither knows of any real-world blazes in those vehicles.

Palo Alto, California-based Tesla's stock rose more than 400 percent earlier in the year as the Model S won accolades from Consumer Reports and other magazines. But it has fallen 37 percent since news of the first fire was reported on Oct. 2.

Tesla shares rose $4.74, or 3.9 percent, to $126.32 in morning trading Tuesday.

The Model S can go up to 265 miles (425 kilometers) on a single charge.

The first U.S. Model S fire occurred along a freeway near Seattle when a car struck a curved metal object which pierced the shield and the battery. In the second case, a Model S caught fire Nov. 6 near Smyrna, Tennessee, after the driver struck a trailer hitch in the road. Another fire was reported Oct. 17 in Mexico when a Model S burned after a high-speed crash.

Explore further: Third fire in Tesla Model S reported

More information: National Highway Traffic Administration report: www-odi.nhtsa.dot.gov/acms/cs/… NOA-PE13037-1867.PDF

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Eikka
1 / 5 (1) Nov 19, 2013
There are about 13,000 Teslas sold in the US so far between June 1, 2012 and today.
There are approx. 254,212,610 registered passenger vehicles in the US
There are approx. 150,000 vehicle fires in the US every year

Therefore the probability of fire is 1:1700 per year.
The probability of a Tesla catching a fire is 1:4333 so far but we don't know if that is true.

Electric cars command approximately 5.11e-5 share of all vehicles and if we assume they catch fire just as often as any car, there should be approximately 7 cases of fire each year. If you count the number of Teslas, Mistubishis, BYDs, Fiskers, Volts etc. that have burned in the last year you actually do get that many electric car fires if not a couple more. Even if we were talking about just the Teslas, the statistical difference between 3 and 7 cases is not very significant - it's more a matter of luck so far.

So Elon Musk's claim that electric cars are safer in terms of fire is clearly not founded on reality.