The bottom line is, Chevy Volts and all the other vehicles that use lithium-ion batteries are safe, because they've been engineered to handle the problems that are inherent in those chemistries.
That's not to say that anomalies won't occur. But even for the most skeptical of us, it's got to be hard to believe that all of the engineers at GM, Ford, Nissan, Mitsubishi, Tesla, Toyota, BMW, and every other maker of electric cars and hybrids could have badly miscalculated the risks. No, the fact is, they knew the risks going in, and they've engineered for them.
The cooling system in the Chevy Volt's battery was designed to handle the potential temperature instabilities of lithium-ion batteries. (Photo courtesy of GM.)
In truth, the real downside of those risks is the cost that's required to manage them. That's why so many industry experts quote high prices when they talk about EV battery costs. Automakers don't just slap blocks of cells in hollowed-out car trunks. They invest heavily in designing and building cooling systems. Then they lay out more money to cover warranties, failures, and liabilities. If the Volt fires tell us anything, it's that carmakers have good reason for doing so.
Sadoway of MIT believes that cost, not safety, could be lithium-ion's Achilles heel. "Cooling systems can be built for this application, but cost is an issue," he writes. "In my judgment, the long term solution is to replace the electrolyte with something that is less capable of being rendered unstable."
In the two weeks since the Volt story came to light, news sites have had a field day. Time Magazine asked, "Are electric cars safe?" The New York Times called it a "setback for electric cars." And scores of bloggers opined that it was "only a matter of time" and that GM's response was "troubling."
But if we're worried about the safety of electric cars, we shouldn't be. Consider this: Every day, most of us sit in vehicles that burn gasoline. The gas runs through fuel lines beneath us and around us to an engine, where it explodes repeatedly.
>"If that was a gasoline car that was not properly constructed, and the gasoline burst into flames, it would have been a far worse accident, because of the big difference in energy," Cairns says. "Yet, we accept the tank of gas, and the energy that it represents, and the type of fire that it represents, every day."
Yes, we accept the tank of gas because we trust the engineers to beat the risks. And the situation should be no different in the case of the Volt.
To keep up with our Chevy Volt coverage, go to Drive for Innovation and follow the cross-country journey of EE Life editorial director Brian Fuller. On his trip, sponsored by Avnet Express, Fuller is driving a Volt across America to interview engineers.
I'm curious about the stats on the problem/non-problem. Is this a rare occurrence or is it statistically significant -- as the Ford Pinto was? Also, are there certain circumstances in which a fire occurs? The story shows an impact test. Is this how the fires get started?
It is very surprising to me (and unprecedented) that GM has extended the offer to buy back the car from worried owners. I would think that if you were going to buy a Volt, you would have done extensive research before handing over the money and driving off the lot. It seems any question of the car's potential safety issues should have surfaced long ago.
I don't think these issues are widespread and from what I've read, there were extenuating circumstances with a least a couple of the fires that might lead you to believe there was another cause--not the lithium ion battery. I think Chevy is offering the buy-back program to uphold their brand image and their commitment to the Volt and be seen as proactive, rather than reactive. The number of vehicles they're likely to buy back will pale in comparison to the upside of making consumers comfortable with their choice.
Rob: Various news reports have mentioned the Volt in conjunction with three fires (see Brian Fuller's story at http://www.designnews.com/author.asp?section_id=1386&doc_id=236254), but two appear to have been unrelated to the Volt. So at this point, it's fair to say there's definitely no statistical significance. As for how the fires get started: Yes, impact can potentially play a role if the casing around the cells is dented, but we don't know if it played a role in this case.
Thanks for the additional information on the active cooling systems used for Li-Ion batteries. I agree with your assessment that engineering cost is a primary negative factor when considering the system-wide distribution and utilization of EVs based on this technology.
I don't do this casually, but there is a direct correlation between these Li-ion battery systems and Fission reactors: both require ACTIVE cooling. However, in the case of Fission reactors, destruction of the active cooling system is very rare and only occurs after secondary and tertiary redundant fail-safe systems have been compromised or damaged (as in the cases of TMI, Chernobyl, and Fukushima). Without data mining into the type of accident, a search estimates around 6 million vehicle collisions per year in the US -- each an event in which the active cooling system of an EV could be damaged or compromised.
The NHTSA has released a statement dated Nov 25, 2011 (http://goo.gl/Aww3m) describing the original fire that resulted more than three (3) weeks after a test crash in May 2011 and two (2) additional fires from tests recently performed on November 17 and 18, 2011. These recent tests employed protocols to specifically damage the battery cooling system. No roadway fires have been reported from the 6,000 Volts currently in use by customers. Multiply the number of sold Volts by 1000 and crash each one of them every year and it is not difficult for the risk analysis folks to set off some read flags.
My first vehicle at 16 was my family's 1971 Ford Pinto. My wife was involved in a near-fatal accident as a college student while riding in a Ford Pinto and investigators said she could thank the same torrential rain storm that caused the accident for preventing the ignition of the fuel that covered her and the car. We must continue to demand that accurate science and sound engineering practices win out over political and branding pressures in the development of Li-Ion EV technology.
Thanks, Bill for your comment. It sees like with the Volt fires, as with the Toyota unintended acceleration of a few years ago, there's no attempt to place the problem reports in context. First off, anecdotal reports, real or not, take on a life of their own and are reported and rereported until it makes it seem like there's a groundswell. Not that these initial three fires didn't take place. What I'm saying is, the results of the investigations never get passed around as a follow up. It was the same thing w the Toyota, which in retrospect involved many cases of driver error. As for the GM buyback offer, that's simply good crisis PR management.
This is getting more and more blatant, they are trying everything in there power to kill any technology that can compete with fossil fuels; why not, they've been doing it for 50 years. I mean, please, if your concerned about car fires, you shouldn't be driving a on top of a 14 gallon can of gasoline. To bring to light the manipulation of the arguement, as stated in previous articles there have been 3 Volt fires reported, EVER! 2 of them did not originate from the Volt, as proven by firemen, and the 3rd was a car that was previously involved in a head on collision and was driven without inspection or service. In contrast, Here are some statistics:
Also according to the NFPA, 33 car fires are reported every hour across the country, with one person per day dying in a car fire accident in the years between 2002 and 2005.
· According to the National Fire Protection Association, there were 258,000 vehicle fires in 2007 and 385 deaths. There were 1,675 injuries.
· There is a vehicle fire every 96 seconds in the United States.
So, if your a person who is overly concerned about car fires, which is more of a concern, a gasoline car or an electric car?
If your Chevy, which should you be more concerned about, the Volt or every other gas car they produce? I mean some on, Chevy gasoline car fires are responsible for hundreds of deaths per year, yet I don't see them offering to take those back at no cost to the owner...hence the manipulation. Chevy is corrupted by big oil and they will do anything, even if it defies logic and common sense, to maintain that relationship with big oil.
The comparison with a gas engine points out the inherent problems with lithium, not similarities. If there is an accident, the first thing that happens in a gas powered car is the fuel pump shuts off, denying the accident scene fuel. Where gasoline is burned we are protected by cooling systems, lots of metal, and a firewall. Nothing like that can be done for a lithium battery: in an accident not only do you get the mechanical conditions for a short and subsequent overheating INSIDE the fuel supply, but loss of cooling is also probable. Do you get an explosion proof firewall with lithium? doubtful.
A better comparison would be with a nuclear power plant. If a plant shuts down (for any reason), backup power is required to keep the core cool, or you get what happened in Japan. If the cooling system (or what powers it) is compromised you get a chain reaction (just like with lithium).
Nothing is risk free (gasoline powered cars certainly are not), but be careful not to unrealistically minimize the risks for the greater cause of "greenliness" or technology for technology's sake.
I think the fire possibility isn't really anything to worry about. I think it may have the fear of electricity stigmatism more than anything. Kind of like the fact that the gas tank was located in the bottom of pintos scare. The pinto was well before my time and I really don't understand what the scare was with pintos was. I have one and have worked on just about all the classic mustangs and they all have the top of the gas tank as the trunk floor and you can see the back of the rear seat in the trunk. 500,000 mustangs sold and seems most everyone enjoyed owning the car. Lots of cars other than the pinto where built this way. I hope the volt falls into the mustang category and not the pinto.
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