Thomas Habetler, an electrical engineering professor at Georgia Tech, theorized that the highway debris punctured a shield and a battery cell, causing a short-circuit, bypassing fuses and electrically linking one battery terminal to another. "You're going to have arcing and sparking in that case, which can cause whatever it is to light on fire," he said. Leaking battery coolant also could have caused a short-circuit, he said.
Habetler and Rizzoni said electric cars are designed to withstand blows from highway debris. Fires are so rare that this one shouldn't give anyone pause if they're considering one, they said.
"My feeling is this was a case of prodigious bad luck," said Rizzoni.
Tesla said it already has inspected the Model S. Galves wrote that the company's ability to monitor cars remotely should result in a detailed report on the cause. It was still unclear Thursday if federal safety regulators would look into the fire because of the partial government shutdown.
Capt. Kyle Ohashi with the Kent, Wash., Fire Department said crews learned lessons from fighting the Tesla fire. For one, the dry chemical extinguisher seemed to work better than water to combat the blaze. And he said the department is now aware that accessing the battery pack in a Tesla is quite difficult.
Ohashi said firefighters may need a course on how to handle electric cars. He also said Tesla may provide guidance.
"Maybe now they'll come up with some sort of procedure to share with our industry," he said.
Rizzoni said he's sure Tesla and other automakers already are working on ways to better protect batteries. "Sometimes you don't know you have a problem until it happens," he said.
The video didn't shake the confidence of one Tesla owner.
Matthew Ng, 41, a business analyst in New York, bought an $80,000 Model S in June and said he's confident the car is safe.
"The car was smart enough to tell (the driver) to get off the road," he said. "Which other car will tell you that?"