2013 Telsa Model S safety rating

The 2013 Tesla Model S recieved five out of five stars from the NHTSA in every test, including pole impact seen here. The Tennessee pole didn't look much like this; neither did the Model S. (safercar.gov / August 20, 2013)

The second fire of a Tesla Model S in the same month has prompted renewed doubt on the safety of electric cars. The aftermath of a high-speed crash of the luxury performance car in Mexico Oct. 18 was captured on video and has been making the rounds, causing Tesla’s skyrocketing stock to plummet more than 7 percent since the market's Monday opening.

The car was speeding through a roundabout in Merida, a city in the northern Yucatan Peninsula in Mexico, when “it hit a raised pedestrian crossing and briefly took flight before crashing into a wall and tree,” wrote Justin Hyde for Yahoo! Autos.

The driver and “perhaps a couple of passengers” walked away from the scene.

(Cuidado: explicit Spanish language) 

Skittish investors might not be paying attention to that last part: The driver and passengers walked away from a 4,600-pound car that “took flight” before crashing into a wall and a tree. Check out the bent rear axle and other damage. Imagine the speed it had to have been going and the subsequent impact it had to go airborne, hit a wall, then a tree. 

Tesla stoked controversy earlier this year by claiming it earned the highest safety rating ever by the National Highway Traffic Safety Administration(NHTSA) -- claiming 5.4 points out of 5, which was later recanted. Still, it earned 5 out of 5 stars for safety on all the tests.

Earlier this month, Tesla stock stumbled on news of a Model S catching fire in Seattle. The culprit was a piece of road debris classified as “a large metal object” that evidently fell off a semi-truck on a highway. The piece impaled the underbody of the electric car, where the massive battery pack is, and caused the fire.

The driver walked away.

Responding to that fire on Oct. 4, Tesla CEO Elon Musk wrote: “A fire caused by the impact began in the front battery module – the battery pack has a total of 16 modules – but was contained to the front section of the car by internal firewalls within the pack. Vents built into the battery pack directed the flames down towards the road and away from the vehicle.”

The NHTSA did not investigate the fire, stating there was "no evidence that the fire...resulted from a Model S defect."  

There is an average of 152,300 automobile fires a year, according to the National Fire Protection Association. When electric cars catch fire, however, there is a furor. In 2011, a Chevy Volt caught fire three weeks after it had been in an accident, prompting NHTSA to restate guidelines to disconnect the battery of an electric vehicle to be serviced after a crash.

Lithium-ion battery packs have been under scrutiny since a 2006 recall of Sony laptops catching fire because of overheated lithium-ion batteries. That scare conflagrated early this year with Boeing’s troubled 787 Dreamliner, which had issues with the lithium-ion battery pack that powered the plane’s electrical systems when the engines were off.    

The FAA grounded the Dreamliner until modifications to the battery pack got it back up in the air last month.

Yet Li-ion batteries, which pack more energy into smaller packs, are considered statistically very reliable, with failure in about 1 in 10 million cells, according to Mitch Jacoby writing for Chemical and Engineering News.

A Model S can use up to 8,000 Li-ion fuel cells, depending on motor size, which may increase the risk of fire.

Despite built-in safety devices, the safety of lithium-ion batteries is being addressed by chemical engineers at the full system level, according to Jacoby.

The fires demonstrate the need for increased safety testing of Li-ion battery packs but do not suggest that electric vehicles are unsafe or that the nascent electric vehicle industry is untested. To the contrary, every electric vehicle falls under NHTSA's New Car Assessment Program (NCAP), which tests the majority of models introduced that year. 

The two high-profile fires, fueled by viral videos, have caused a panic that is not justified. 

In both Model S fires, the drivers walked away from high-speed accidents, and both anticipated delivery of another Model S.

Accidents happen. It’s the reaction to the accidents that have the most enduring impact.


Twitter @dufferrobert