Detroit —Tesla Motors said Tuesday it is recalling more than 29,000 Model S vehicle 240-volt charging adapters that could overheat and cause a fire. The company will update software in the electric vehicles and send owners replacement adapters.
The Palo Alto, Calif., automaker told the National Highway Traffic Safety Administration that its review found that defective or improperly installed wall receptacles that the adapter plugged into could cause problems, including melted adapters and or a fire. While the number of incidents remains small, and Tesla's review to date points to the building or wiring as the primary cause of failed adapters, "the company has determined that a voluntary recall is appropriate as a precautionary measure," Tesla said.
Since late 2012, Tesla said 2.7 percent of universal mobile connector adapters have been returned and "showed signs of internal damage only and that stopped vehicle charging."
Tesla said the problem was not a safety issue. Late last year, Tesla became aware of several events that resulted in fire damage external to the charger. Tesla began a review, including a highly publicized fire that took place in Irvine, Calif., which is prompting the recall.
Tesla will notify owners and provide an "over-the-air" software update. Some owners have already received this update. This update allows the Model S on board charging system to detect any unexpected fluctuations in the input power or higher resistance connections to the vehicle. If detected, the system will automatically reduce the charging current by 25 percent. Tesla owners can verify that they have received the updated software on the vehicle's center information screen. The move will substantially reduce "the heat generated in any high resistance connections outside of the vehicle."
Tesla is also mailing owners a replacement adapter that is equipped with an internal thermal fuse, but hasn't set a schedule for sending the adapters. Tesla says the improved design and addition of the fuse will act to provide a higher level of reliability. "Tesla does not believe the improved adapters are required to address the issue, but is including this measure to ensure confidence in all Tesla-branded products," the automaker said.
In November, NHTSA opened a formal investigation into 13,100 Tesla Motors Model S electric cars after three reports of battery fires that occurred after accidents.
The preliminary investigation came as Tesla said it would extend warranty coverage to fire claims and is making changes to make the vehicles less suspectible to striking roadway debris. In August, NHTSA had awarded the car a top safety rating.
The announcement of the investigation came after NHTSA had said in October it would not open a formal investigation after a fire in Kent, Wash., occurred when debris struck the underside of a Model S and caused the battery to catch fire. After a fire in Mexico and a fire earlier this month near Smyrna, Tenn., NHTSA decided to open an investigation.
NHTSA said in both of the incidents in the U.S., fires occurred after the undercarriage of the cars hit metal debris on the road, which damaged the battery tray and caused “thermal runaway.” “In each incident, the vehicle’s battery monitoring system provided escalating visible and audible warnings, allowing the driver to execute a controlled stop and exit the vehicle before the battery emitted smoke and fire,” NHTSA said.
Tesla is working to improve the clearance between the bottom of the car to reduce impacts with debris, Musk said. Software updates will cause the air suspension to create greater ground clearance at highway speeds.