Tesla blaze renews safety concerns with electric cars

PUBLISHED : Friday, 04 October, 2013, 2:10pm
UPDATED : Tuesday, 24 November, 2015, 12:03pm

When debris on a freeway near Seattle, Washington, pierced the battery of a US$70,000-plus Tesla Model S and touched off a raging fire, it raised new safety concerns for owners of electric cars.

It also caused rare jitters among investors, who of late have viewed Tesla as nearly invincible.

Electric vehicles have scored well in government tests of front and side crashes – the Model S earned the highest score possible. But Tuesday’s incident demonstrates that real-world driving could reveal some vulnerabilities that don’t show up in labouratory testing.

“The safety challenges related to electric cars are still in the early stages of being tested and addressed,” said Karl Brauer, senior analyst at car guide publisher Kelley Blue Book.

Tesla said the driver hit a large metal object in the road, which damaged a battery cell and caused a fire. The company said the car acted as designed by containing the blaze in the front of the vehicle.

Still, experts said on Thursday that while incidents like this will happen again, they are rare. And electric cars are still safer than those with petrol engines that haul around a tank full of flammable fuel.

The Tesla fire also shows that carmakers need to bolster the shields around batteries and that firefighters need more training to deal with electric-car blazes.

Of the estimated 194,000 vehicle fires in the United States each year, the vast majority are in cars and trucks with petrol or diesel engines. Electric vehicles make up less than 1 per cent of the cars sold in the US.

Tesla says this is the only fire ever to happen in one of its batteries.

Although a Chevrolet Volt made by General Motors caught fire two years ago after a government crash test, neither GM nor Nissan, which make the top-selling electric cars in the US, know of any real-world blazes in their vehicles.

In May last year, flames erupted, killing three people, when a BYD e6 electric taxi collided with a sports car in Shenzhen, but it was unclear what caused the blaze.

“If you think about what you’d rather be close to, 10 gallons of gasoline or a battery pack, I’d pick the battery pack every day,” said Giorgio Rizzoni, director of the Centre for Automotive Research at Ohio State University, where he is a professor of mechanical and electrical engineering.

Still, an internet video of the Tesla fire spooked investors and caused a sell-off on Wednesday and Thursday. Tesla shares fell 6 per cent Wednesday, and they closed Thursday down 4.2 per cent, at US$173.31.

At that price, Tesla’s market value has dropped about US$2.4 billion in the past two days. Still, if an investor purchased a share of Tesla at US$35 on January 2, he or she is sitting on a gain of nearly 400 per cent.

Tesla has dazzled Wall Street by selling more vehicles than expected and posting its first quarterly net profit earlier this year.

If you think about what you’d rather be close to, 10 gallons of gasoline or a battery pack, I’d pick the battery pack every day
Engineering professor Giorgio Rizzoni

Deutsche Bank analyst Dan Galves, in a note to investors on Thursday, said he expects bad news and investor concern to push down Tesla shares in the short term. Investors, he said, will be concerned, because electric cars represent a new technology with a high sensitivity to safety risks.

But Galves wrote that the Model S has been collectively driven more than 134 million kilometres, yet this is the first fire despite 12 significant crashes and extreme testing by the government.

“We have confidence that this is an isolated incident that could happen to any vehicle,” Galves wrote.

Tesla said that on Tuesday the Model S warned the driver of problems from the collision. He pulled off the road, smelled smoke and saw flames.

A company spokeswoman said the fire originated in a battery cell damaged in the collision, and the car’s design prevented the fire from spreading to the rest of the battery and contained it in the front.

Thomas Habetler, an electrical engineering professor at Georgia Tech, theorised that the highway debris punctured a shield and a battery cell, causing a short-circuit, bypassing fuses and electrically linking one battery terminal to another.

“You’re going to have arcing and sparking in that case, which can cause whatever it is to light on fire,” he said. Leaking battery coolant could also have caused a short-circuit, he said.

Habetler and Rizzoni said electric cars are designed to withstand blows from highway debris. Fires are so rare that this one shouldn’t give buyers pause if they’re considering one, they said.

“My feeling is this was a case of prodigious bad luck,” said Rizzoni.

Tesla said it has already inspected the vehicle that caught fire. Galves wrote that the company’s ability to monitor cars remotely should result in a detailed report on the cause.

It was still unclear on Thursday if federal safety regulators would look into the fire, because of the partial government shutdown.

Captain Kyle Ohashi with the Kent, Washington, fire department said crews learned lessons from fighting the Tesla fire. For one, the dry chemical extinguisher seemed to work better than water to combat the blaze.

And he said the department is now aware that accessing the battery pack in a Tesla is quite difficult.

Ohashi said firefighters may need a course on how to handle electric cars. He also said Tesla may provide guidance.

“Maybe now they’ll come up with some sort of procedure to share with our industry,” he said.

Rizzoni said he’s sure Tesla and other carmakers are already working on ways to better protect batteries.

“Sometimes you don’t know you have a problem until it happens,” he said.