The connection had been tightened by hand, not by a robot.
Tesla has concluded its investigation into the apparent spontaneous combustion of a Model S, saying that the fire was caused by an “improperly tightened” bolted electrical connection, reports Electrek.
The fire occurred last month during a test drive at a promotional event in France. At the time, it was reported that the car in question - a Model S P90D - started making a loud noise before a "problem with charging" warning message was shown on the dashboard. A Tesla employee who was in the car asked the driver to pull over. Both they and a third person were able to get out of the car before it erupted into flames.
Firefighters were soon at the scene, but witnesses described the car burning to the ground within five minutes. Tesla launched an investigation into the incident and announced its findings last week.
Speaking about the cause of the fire, Tesla’s French communications manager, Charles Delaville, said: “Usually, these electrical connections are installed by a robot, but for this car this connection was installed manually. There has never been a similar incident in another one of our cars.”
As yet, no statement has been given by Tesla as to why the connection was installed manually, rather than by a robot that would apply the correct torque automatically.
There have been other instances of Tesla’s catching fire, but most have occurred as the result of a crash, as we saw last week. Back in 2014, extra underbody protection was added to reduce the likelihood of fires caused by strikes to the chassis.
There has also been one case of a car catching fire while plugged into a Supercharger station, which was chalked up to a short circuit in the car’s distribution boxes. Other fires involving Teslas are thought to have been caused by outside factors.