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In response to a federal probe of battery fires in crash-tested Chevrolet Volts, GM took the unprecedented move of offering Volt owners free loaner cars and vowed that the car was safe.
But Yahoo! Autos has found that Chevrolet Volt owners have been reporting a different problem for months: Overheating and melting of the cord used to charge the car from standard 120-volt household electrical sockets. While GM says the cords are safe and blames the problems on the owners’ wiring, it has replaced an unknown number of cords and made changes to its design.
No fires have been reported from the cords, nor have any complaints been reported to the National Highway Traffic Safety Administration. Yahoo! Autos learned through an exclusive source that the problem did catch the attention of one electric utility which had a Volt cord melt while the car was charging -- and suspected the cord’s construction played a role.
The cord supplied with every Volt is meant to work as a stopgap for a dedicated charging station that GM and other automakers expect electric vehicle owners to install. It consists of a black control system and two yellow extension-cord lengths, one running to a grounded 120V plug, the other to the charger that plugs into the car.
Since the Volt’s rollout last year, several owners have posted on the GM-Volt.com forum reporting troubles with the 120V cord. According to an informal poll on the site, 19 of 53 users responding have had some kind of fault with the cord that has required replacement, with five saying their 120V cords needed to be replaced twice.
Most of the replacements were due to the cord failing to charge the Volt, triggering an error in the car’s systems. But a number say the cord overheated or even melted while charging.
In March 2011, a Volt owner from Delaware said the cord “got so hot it caused a 2nd degree burn to my wrist when one of the prongs brushed against me while winding it up.” In late June 2011, one Volt owner from Rancho Mirage, Calif. wrote this of his 120V cord:
“Mine is being replaced and I hope to have it tomorrow. It was 158 degrees a couple of months ago when I measured it with a laser thermometer and was much hotter yesterday when I felt it. It was melting and deforming the wall end plug and discoloring. I would guess it is now more than 170 [degrees Fahrenheit]. I have only one layer of cord wrapped on the reel. I checked and my receptacle is grounded and connections tight so it must be the charge cord. I have seen several others that have had a replacement and [the] second one runs cooler. GM should get serious on this as it looks dangerous.”
That same month, another Volt owner posted that his cord had “got so hot that it (1) welded itself to an attached power meter's plastic housing and (2) liquefied and then extruded some insulation within the plug body. Needless to say, this was an alarming discovery.”
Those reports followed one from a Volt customer who snapped the photo above in October 2010 after plugging the Volt into a multi-outlet adapter in his garage. Admitting it was his fault for using an adapter, the owner still warned other Volt fans to be cautious: “Somebody might have a serious accident doing something stupid or even stupider than what I did.”
In all cases, the owners said GM replaced the cords without complaint; one told Yahoo Autos he believed the melting was due to faulty wiring in his house. But others have said the demand for replacements was great enough that GM was running short of spares.
According to the parts department at Boardwalk Chevrolet in Redwood City, Calif., it takes 4 to 5 days to receive a replacement 120V cord for the Volt, but "that part's got a hold on it, which means you have to have a tech look at yours before we can order a new one," we were told. GM was “having issues with [the cords], and they want a tech to look at it. I can't sell it over the counter."
The problem was also witnessed by electric utility Southern California Edison, whose engineers found that the cord on one of its Volts created enough heat to melt the plastic at the socket, along with oxidation of the plugs, according to a person close to the company. The utility declined to comment.
While automakers must abide by dozens of federal regulations for designing cars, plugs used for recharging EVs face no uniform standard. Compared to the similar cord that comes with the Nissan Leaf, the Volt’s unit looks cheaper, which it is; the replacement cost of the Volt’s 120V charge cord is $450, while the Leaf’s 120V cord is $600. The Volt’s cord uses brass prongs and a thinner plastic head at the plug, while the Leaf uses nickel-plated prongs.
"People have asked me why there’s such a price difference, and I tell them it's because ours is better," Nissan spokesman Tim Gallagher said.
And unlike the Volt, there are few complaints from Leaf owners about overheating or melting 120V cords, although one Leaf buyer did report a melted plug to NHTSA after charging his Leaf using an extension cord.
General Motors spokesman Randy Fox said GM had made some design changes to the Volt’s 120V cord since launch, but only to deal with cracks where the cord attached to the control system, and were not related to overheating or melting. He also said GM tells Volt owners to have their home wiring inspected before delivery, and that the Volt should only charge from a dedicated 120V plug with no extension cords.
“We’re confident that all of our Volt 120V cord sets are safe,” Fox said, adding that any Volt owner could have their cord inspected or replaced upon request.
NHTSA’s probe of the Volt only extends to the batteries for now, but the agency has pressed for recalls in the past for defects that had the potential to start fires, even if none were reported. Agency spokeswoman Lynda Tran said NHTSA was aware of the melting cords, and would "continue to monitor the issue and will take action to address the problem as necessary." Given the Volt’s mission as an electric vehicle designed to travel hundreds of miles before needing to recharge, the owners' complaints raise the question of whether the Volt’s cord can handle every outlet away from home.
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