Tesla's battery fire in context

Much has been made of last week's Tesla battery fire, but there are 180,000-plus car fires in the US each year, so is this one particularly worrying?

CleanTechnica

Whether you love them or not, electric cars are one of the hot cleantech consumer products that incite people to take notice and make their thoughts known. People comment about electric vehicles a lot. They are green chic. Come on, who does not want a Tesla.

Point of fact: over 180,000 vehicles catch fire on average every year in United States. But a few days ago, a car fire near Seattle (in which not one person was injured) got an abnormal amount of attention. Why all the attention to this one? Because this car was a new, shiny Tesla Model S. Disregard the other 180,000 car fires this year — this one was a Tesla.

Some passing travelers caught the blaze in this video.

As they reflect on the fire, “I can feel the heat in here. Oh sh*t dude, that’s a Tesla.” Not sure if it is the blaze or the Tesla that provoked the astonishment in this passersby more.

Tesla is intent on making electric vehicles mainstream. It’s Model S has achieved the highest safety rating ever given in North America, and it has won “best car of the year” awards from several of the top automobile magazines, as well as numerous other accolades. Yet, the fire sparked a debate about electric car batteries that we somehow don’t have about flammable gas tanks sitting under our butts as we drive.

Tesla’s stock has dropped as a result, which goes to show how fickle the stock market can be. Tesla of course issued a statement on the Model S fire, noting that the car hit something hard and metal in the middle of the road and that the driver was alerted of the fire risk and told to pull over and exit the car. Also noted was the fact that the fire didn’t spread to the passenger compartment.

Here’s part of the statement from CEO Elon Musk:

Earlier this week, a Model S traveling at highway speed struck a large metal object, causing significant damage to the vehicle. A curved section that fell off a semi-trailer was recovered from the roadway near where the accident occurred and, according to the road crew that was on the scene, appears to be the culprit. The geometry of the object caused a powerful lever action as it went under the car, punching upward and impaling the Model S with a peak force on the order of 25 tons. Only a force of this magnitude would be strong enough to punch a 3 inch diameter hole through the quarter inch armor plate protecting the base of the vehicle.

The Model S owner was nonetheless able to exit the highway as instructed by the onboard alert system, bring the car to a stop and depart the vehicle without injury. 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.

When the fire department arrived, they observed standard procedure, which was to gain access to the source of the fire by puncturing holes in the top of the battery’s protective metal plate and applying water. 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.

It is important to note that the fire in the battery was contained to a small section near the front by the internal firewalls built into the pack structure. At no point did fire enter the passenger compartment.

While a lot has been made of this fire, something that I think should really be emphasized more is the wonderful detection and notification system in the Model S that allowed the driver to patiently and easily exit the vehicle without harm, and that also contained the fire to a portion of the battery pack. Nonetheless, humans are not always logical when it comes to such matter. Autoblog Green explains: “Electric vehicle fires – whether they be in China or the US, started while moving or stopped – often become comment fodder, even when we learn after the fact that the electric part of the powertrain has nothing to do with the blaze.”

Autoblog Green also offered up the statistic noted at the top of this article: “For the record, there were 187,500 ‘highway vehicle fires‘ in the US in 2011 (the last year for which data is available), according to the National Fire Prevention Association.”

Nonetheless, while this fire didn’t harm anyone, it may have had a bigger impact in the financial and automotive world than any other automobile fire this year. Jalopnik’s sensational headline, 'This Is What Fiery Tesla Model S Death Looks Like', got the story going, and from there it took off like….

Unfortunately, automobile accidents are a part of basically everyone’s lives in the US. This is another good incentive to get off the highway and take the metro, but many of us don’t have a metro in our region, and many others won’t heed the advice anyway. And, still, I want a Tesla, or another electric car. The fire was solely in the front trunk area. The driver was notified of the risk and safely beyond before it burst into flames. No one else was hit.

As Elon Musk added, such an occurrence in a gasoline-powered vehicle might not turn out so well.

Had a conventional gasoline car encountered the same object on the highway, the result could have been far worse. A typical gasoline car only has a thin metal sheet protecting the underbody, leaving it vulnerable to destruction of the fuel supply lines or fuel tank, which causes a pool of gasoline to form and often burn the entire car to the ground. 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....

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.

Originally published by CleanTechnica. Republished with permission.