Investigators in Iredell County are still sifting the ashes of an Oct. 30 house fire that burned a garage where a Chevy Volt's battery was being charged, but Duke Energy and Progress Energy say it appears neither the plug-in car nor its plugged-in charger was to blame.

The fire sparked concern for both Charlotte-based Duke and Raleigh-based Progress, which have installed free home charging stations in pilot programs for customers who drive Volts and other electric cars.

The National Highway Traffic Safety Administration launched an investigation last week to determine the risk of fire after a Chevy Volt battery is damaged in a crash (see Road Worrier column with reader comments). Bloggers across the country have speculated that faulty plug-in technology started the Oct. 30 house fire.

Damage was estimated at $800,000 for the $1.5 million house near Mooresville, where the Volt and a Nissan SUV were destroyed. The homeowner was one of 65  customers enrolled in Duke's home-charger program.

Garland Cloer, Iredell County's chief deputy fire marshal, said it appears the fire did not start in the electric car. ... [MORE]

The National Highway Traffic Safety Administration said today it will open a formal safety defect investigation to assess the risk of fire in Chevy Volts that have been damaged in crashes.  The probe, spurred by two Chevy Volt battery fires that followed NHTSA crash tests, could mark a setback for GM and its plug-in electric hybrid car.

The announcement came a day after a Chevy Volt battery caught fire at a NHTSA test facility Thursday, one week after it had been intentionally damaged in a crash test.  It was the second battery fire after a NHTSA test this year.

The first fire, in May, broke out in a parked Volt after it had been deliberately crashed in a NHTSA test designed to measure the vehicle's ability to protect occupants from injury in a side collision. The crash damaged the car's large lithium-ion battery and ruptured the coolant line, and NHTSA blamed the fire on the damage to the battery.

NHTSA engineers attempted to recreate the May event in three separate tests last week, on Nov. 16, 17 and 18.  The battery damaged in the Nov. 18 crash test later smoked and emitted sparks.  The battery damaged in the Nov. 17 test, which was monitored later at the NHTSA testing facility, caught fire Thursday, a week later.

Chevy Volt drivers, what do you think about this? Please let me hear from you by email, and don't forget your weekday contact info.  I'll get back with you on Monday.

Meanwhile, NHTSA seeks to reassure Volt owners: ... [MORE]