U.S. auto safety regulators are investigating nearly 40,000 Hyundai Ioniq 5 electric vehicles over reports of power loss while driving tied to a battery charging issue. The National Highway Traffic Safety Administration’s preliminary investigation covers 2022 model-year vehicles after it received 30 consumer complaints alleging a loss of acceleration. The agency said many consumers reported a loud popping noise followed by a warning displayed on their dashboard, and immediately experienced a loss of power that ranged from a reduction in acceleration to a complete loss. 

NHTSA said it learned from Hyundai the failure is related to the Integrated Charging Control Unit (ICCU) responsible for powering both the main electric vehicle and low-voltage 12-volt batteries. A preliminary review indicates too much current within the unit can damage transistors, resulting in the inability to recharge the 12V battery, NHTSA said. 

Hyundai said Monday it is launching a service campaign in July that will update impacted vehicles’ software and replace the ICCU if necessary. “We value our cooperative relationship with NHTSA and have engaged in frequent, open and transparent dialogue with the agency on this topic,” the Korean automaker said, adding it is fully cooperating. NHTSA conducted several owner interviews confirming a range of loss of power and varying time intervals between the warning message and power loss but did not report any crashes or injuries tied to the issue. 

One complaint reported a driver traveling 75 miles (120 km) per hour on a highway using advanced highway assist and “the car became completely unresponsive.” The driver added that there was a semi-trailer truck behind him “and one to my right in the slow lane. The car stopped accelerating, and I was unable to resume driving. I was forced to coast to a stop on the side of the highway.” According to another complaint in February, a driver on a highway in Santa Maria, California, heard a loud pop coming from my car and “within a few seconds my car lost speed rapidly, from 55 mph to 25 then a second later 22 mph.”