Tesla CEO asserts Model S is safe, following vehicle fire

After last week’s Model S fire near Seattle, and subsequent 6 per cent drop in its share price,  it perhaps should come as no surprise that Tesla’s CEO Elon Musk should speak out to confirm that its fully electric car is safe.

According to blog post from Tesla, the fire started when a Model S, travelling at highway speed on the Washington State Route 167 hit a large metal object, which caused significant damage.

That large metal object has now been confirmed as a curved section of metal which fell off a semi-trailer. As the car travelled over the object, the object punctured upward and impaled the Model S with a peak force of 25 tonnes. According to Tesla, only a force of this magnitude would be strong enough to punch a 3 inch diameter hole through the quarter inch armour plate protecting the base of the vehicle.

Despite the damage, the Model S involved in the accident behaved exactly as Tesla hoped it would in the event of such a tragedy. The owner of the car and sole occupant of the vehicle at the time, was able to exit the highway as instructed by the on-board alert system, bring the car to a stop and depart the vehicle without injury.

A fire subsequently started, caused by the impact but was contained to the front section of the battery, contained by the internal firewalls with the 16 module pack.

Although there were some suggestions from the media that the fire-fighters may have mishandled the situation, the carmaker confirms that the fire department ‘observed standard procedure’ on arrival by puncturing holes in the top of the battery's protective metal plate and applying water first rather than dry chemical extinguisher.

Musk wrote: “For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher), but not to puncture the metal firewall, as the newly created holes allowed the flames to then vent upwards into the front trunk section of the Model S. Nonetheless, a combination of water followed by dry chemical extinguisher quickly brought the fire to an end.

“At no point did fire enter the passenger compartment.”

Fire risk very low

As Musk points out in his blog post, such a collision could have been much worse if a gasoline car had been involved. With the typical combustion car only having a thin metal sheet to protect the underbody, such an impact could have destroyed the fuel supply lines or fuel tank, which could have sparked a much bigger blaze.

“In contrast, the combustion energy of our battery pack is only about 10 per cent of the energy contained in a gasoline tank and is divided into 16 modules with firewalls in between. As a consequence, the effective combustion potential is only about 1 per cent that of the fuel in a comparable gasoline sedan,” wrote Musk.

With 150,000 car fires every year in the US, that equates to around one vehicle fire for every 20 million miles driven in the country, “compared to 1 fire in over 100 million miles for Tesla. This means you are 5 times more likely to experience a fire in a conventional gasoline car than a Tesla!”

“For consumers concerned about fire risk, there should be absolutely zero doubt that it is safer to power a car with a battery than a large tank of highly flammable liquid,” the post concludes.

Launched in the US last year, the fully electric saloon has only just arrived in Europe and is expected to launch here in the UK,  in right-hand drive form, before the end of the year.