Tesla battery fire raises safety concerns about electric cars

When debris on a North American freeway pierced the battery of a US$70,000-plus Tesla Model S and touched off a raging fire this week, it raised new safety concerns for electric-vehicle owners.

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

Electric vehicles have scored well in US 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 laboratory 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 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 car.

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 petroleum. The Tesla fire also shows carmakers need to bolster the shields around batteries, and that firefighters need more training to deal with electric car blazes. Electric vehicles make up less than 1 per cent of the cars sold in the US.