(Corrects name of charger in sixth paragraph to "Bosch Power Xpress" from "Bosch Power Express")
April 21 (Reuters) - U.S. safety regulators have opened an investigation of electric car chargers made by German supplier Robert Bosch LLC after a driver of a 2013 Nissan Leaf reported one emitted smoke while charging.
The U.S. National Highway Traffic Safety Administration said in documents filed online over the weekend that it opened the preliminary evaluation into the possibility an estimated 50 chargers may overheat and result in a fire.
A preliminary evaluation is the first step in a process that could lead to a recall if regulators determine a manufacturer needs to address a safety problem.
Bosch spokeswoman Cheryl Kilborn said the company was reviewing the filing and would cooperate with NHTSA's investigation as it seeks to identify the cause.
Nissan spokesman Brian Brockman said in an email the automaker was aware of the probe, which was focused on Bosch, and would assist in the investigation as needed.
The charger used, a Bosch Power Xpress 240V, had been charging for over an hour at 30 amps at a private residence when signs of overheating, including a "strong burning smell," were noticed, according to NHTSA as well as the consumer complaint filed in late August.
"Charging vehicles are typically left unattended and there is a risk of fire that could affect the vehicle and its surrounding environment," NHTSA said.
The consumer complaint said Nissan had determined the car, which had been driven less then 10,000 miles at the time, was not to blame for the incident.
The Bosch charger is primarily marketed to residential customers and is used to charge a wide variety of electric vehicles, NHTSA said. (Reporting by Bernie Woodall and Ben Klayman in Detroit; Editing by Meredith Mazzilli)