After a Tesla Model S burned on a Seattle highway last week, Elon Musk has spoken: Gas-swilling drivers are five times more likely to have their car catch on fire than a Tesla. Unlike the last time the Tesla CEO went to bat against critical media reports, there was no New York Times or unfavorable review to tar and feather last week, only bad luck and physics.
As we reported, there really wasn’t a big deal to the Model S fire given it had only happened one time and was completely contained. Indeed, we now know that a “curved section” of metal fell off a tractor-trailer and punched a hole—with a force of 25 tons—through the car’s quarter-inch-thick armor plating that protects the battery pack. In scientific terms, it would appear as though there was an ensuing short circuit from the impact, then what’s known as a thermal runaway—when a battery’s temperature keeps rising and its energy essentially consumes itself—and finally, a fire. (Tesla would not comment nor confirm this speculation.) It was an accident, and like any accident with a moving vehicle that propels itself with a chemical process, fires can and do happen.
But while Musk references stats from the National Fire Protection Association and the Department of Transportation to draw his above conclusion—including his suggestion that gasoline leaks in a similar accident would “burn the entire car to the ground”—we also know that lithium-ion battery R&D is a relatively new line of work.
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Researchers at MIT published a study in May 2012 in which they punched lithium-ion batteries with varying strikes and force. They found that physical impacts can cause increases in temperature and wrote that it was “very important to detect onset of electric short circuit” even without an imminent fire condition. This isn’t to say that Tesla hasn’t engineered a great car, or that gasoline is inherently safer than batteries. Neither is true. We all just have a lot more to learn about how these batteries fail—and how they can be made stronger—in a car crash.
Source: CarAndDriver
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