Autos

Battery Fires Begone: Tesla Looks to Titanium Armor for Help

Tesla Model S White

Last year, electric vehicle upstart Tesla Motors found itself in a very unwanted spotlight after two of its vehicles suffered fires in isolated incidents as a result of running over debris strewn across the road. The incidents caused the stock to sink, since electric cars have not yet endured the test of time, and no one — investors especially — was particularly sure if it was merely bad luck or an engineering fault that would potentially affect all of Tesla’s Model S sedans on the road to date.

As it has developed a reputation for doing, Tesla handled the incidents in stride. It sent out an over-the-air update to raise the suspension ever so slightly to mitigate the risk of a battery cell puncture, while CEO Elon Musk publicly battled the media at large for its disproportionate coverage of the fires — maintaining correctly, we might add, that the risk of a fire in a Tesla was still far below the risk of fire in an internal combustion-driven vehicle.

However, in efforts to do one better, Musk and company have penned a statement that was published through Medium.com, where he says in addition to the software updates, Tesla will be adding a titanium plating to further protect the battery pack from punctures and damage.

“It is important to note that there have been no fire injuries … in a Tesla at all,” he said. “The odds of fire in a Model S, at roughly 1 in 8,000 vehicles, are five times lower than those of an average gasoline car and, when a fire does occur, the actual combustion potential is comparatively small.

“However, to improve things further, we provided an over-the-air software update a few months ago to increase the default ground clearance of the Model S at highway speeds, substantially reducing the odds of a severe underbody impact.”

Tesla Model S

“Nonetheless,” he continued, “we felt it was important to bring this risk down to virtually zero to give Model S owners complete peace of mind. Starting with vehicle bodies manufactured as of March 6, all cars have been outfitted with a triple underbody shield. Tesla service will also retrofit the shields, free of charge, to existing cars upon request or as part of a normally scheduled service.”

Tesla performed more than 150 tests, and in each situation, the shield effectively “prevented any damage that could cause a fire or penetrate the existing quarter inch of ballistic grade aluminum armor plate that already protects the battery pack.” Further, these were not just casual road tests — Tesla went out of their way to ensure the “accidents” were meant to cause as much damage as possible. This included some “hardened steel structures set in the ideal position for a piking event, essentially equivalent to driving a car at highway speed into a steel spear braced on the tarmac.”

“The first of the three shields is a rounded, hollow aluminum bar that is designed to either deflect objects entirely or, in the case of a self-stabilizing, ultra high strength object, like a three ball steel tow hitch, absorb the impact and force it to pike upwards well forward of the battery pack,” Musk explained. “This pierces the plastic aeroshield and front trunk liner, but causes no damage affecting safety and the car remains in control and drivable before, during and after the impact.”

The titanium plate is next, and reportedly prevents “sensitive front underbody components” from being damaged and “aids in neutralizing the road debris,” Musk said. In a series of animated images in the original blog post, we can see how effective it is — the trailer hitch does more damage to the road than the car, a sizable concrete block shatters on the impact, and an alternator from an internal combustion engine explodes into pieces.

Just in case it wasn’t enough, though, Tesla has added some more protection for good measure. “For the rare piece of debris that remains intact, we added a third shield, which is a shallow angle, solid aluminum extrusion that further absorbs impact energy, provides another layer of deflection and finally causes the Model S to ramp up and over the object if it is essentially incompressible and immovable,” Musk wrote.

So what will all this armor do to the car’s performance? “In total, the shields only have a 0.1 percent impact on range and don’t affect ride or handling. Wind tunnel testing shows no discernible change in drag or lift on the car,” Musk said, though he didn’t disclose the amount of weight added to the car. Given its minimal impact on range (a 2.6 mile deficit on Tesla’s range-topping 265 mile Model S), it probably is not a lot — titanium is also renowned for its lightweight nature.

“With a track record of zero deaths or serious, permanent injuries since our vehicles went into production six years ago, there is no safer car on the road than a Tesla,” Musk concluded. “The addition of the underbody shields simply takes it a step further.”