DETROIT — General Motors is advising Volt owners to return their electric cars to dealers for repairs that will better protect the vehicles' batteries, which have caught fire after crash tests.
The repairs— which would fix 8,000 Volts on U.S. roads and another 4,400 still for sale — fall under a "customer service campaign," which is similar to a safety recall but allows GM to avoid the bad publicity and federal monitoring that come with a recall.
GM's move comes after three Volt batteries caught fire at government test sites last year. The fires followed side-impact crash tests done by federal safety regulators. They occurred seven days to three weeks after the crashes, which damaged the plastic battery pack and caused coolant to leak. The coolant then caused an electrical short, which sparked the fires.
Dealers will add steel to a plate that protects the Volt battery, spreading the force of a crash over a larger area, says Mary Barra, GM's product development chief. Tests have shown that the repairs stop penetration into the battery and prevent coolant leaks, GM and federal safety regulators say.
GM has a huge incentive to fix the problem and protect the image of the Volt. The Volt isn't a big seller — it's fallen short of sales goals — but it burnishes GM's image as a greener, more innovative carmaker.
"We have made the Volt even safer," Mark Reuss, GM's North American president, said Thursday.
GM says it wasn't forced by the government to repair the car. The automakers and the National Highway Traffic Safety — the federal safety agency — say no fires have broken out after Volt crashes on real-world roadways.
NHTSA began studying the Volt batteries after a car caught fire in June at a test facility in Wisconsin. The fire broke out three weeks after a side-impact crash test.
NHTSA opened an investigation into the Volt's safety in November following that fire and two others that occurred after crash tests.
Then, in late December, the agency crashed a Volt with the added steel. "The preliminary results of the crash test indicate the remedy proposed by General Motors today should address the issue," NHTSA says. The agency says it will monitor the car for another week and will continue its investigation.
GM said the Volt's battery should have been drained after crashes but it never told NHTSA to do that. Later, two GM executives said the company had no formal procedure to drain the batteries until after the fire.
The company now sends out a team to drain the batteries after being notified of a crash by GM's OnStar safety system.
The company sold 7,671 Volts last year, falling short of its goal of 10,000. It was outsold last year by its main electric car competitor, the Nissan Leaf, at 9,674.
The Volt has a T-shaped, 400-pound (181-kilogram) battery pack that can power the car for about 35 miles (56 kilometers). After that, a small gasoline generator kicks in to run the electric motor.