NHTSA Preliminary Evaluation PE11037

The subject vehicles, which employ emerging technology, are range-extended electric vehicles that utilize a high voltage (HV) battery to provide energy for propulsion. The HV battery is lithium-ion based technology that has a nominal full charge of 390 VDC, a 16 kWh capacity, and a control system that incorporates liquid (antifreeze) cooling and various electronic devices (control modules, sensors, wiring, etc) to monitor and manage the HV battery. The HV battery, portions of the cooling system, and the control system are contained within a common enclosure.During an NCAP oblique side pole impact test conducted by NHTSA in May 2011, the pole struck and deformed the sill plate under the driver's door at a location where there is a structural member. The lateral member displaced inward, pierced the HV battery enclosure and battery, and caused a battery coolant leak. Thereafter, the Agency conducted a rollover test (the rollover test consists of four 90-degree rotate-and-hold movements about the vehicle's longitudinal axis). In that test, the HV battery and electronics were exposed to coolant that leaked as a result of the crash. The vehicle fire that occurred three weeks later and the additional testing NHTSA conducted are discussed in a report titled 2011 Chevrolet Volt Battery Fire Incident Report a copy of which is available in the public file. The report indicates that intrusion induced coolant leakage, and subsequent rollover that saturates electronic components, were the only test conditions which resulted in a subject vehicle HV battery fire.GM announced its intention to conduct a free-of-charge customer satisfaction campaign (CSP) on the subject vehicles on January 5, 2012. The action affects 14,735 vehicles produced prior to December 21, 2011. The CSP addresses three areas related to the issue under investigation. The first involves a modification/strengthening of the structure of the vehicle in the area where battery intrusion occurred in the May 2011 test.