How can an iPod set your pants on fire -- literally?

There have been several instances of iPod nanos (above) catching fire. The magazine Wired has a gallery of burnt iPod images that users have sent in. See more iPod pictures.
Photo courtesy Chris Hondros/Getty Images

During his shift at Atlanta's Hartsfield-Jackson International Airport, Danny Williams found that something unusual was happening to his pants. They were on fire. The Apple iPod Nano that Williams had in his pocket had caught fire, and the flames reached to his chest. Luckily, Williams was able to put the fire out without suffering any serious physical harm. He told a local news station that he had a piece of coated paper in his pocket, which he believes protected him from being burned [source: WSB-TV].

iPod Image Gallery

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After Apple heard about the incident, the company asked Williams to send his burned iPod to them and promised to furnish him with a new one. But while Apple reacted quickly to help one of its customers, the company is probably still holding its breath back at corporate headquarters. Williams' burning iPod is just one example of a rash of consumer electronics that have caught fire , costing companies millions of dollars. Williams, you see, is not the first to suffer electronic spontaneous combustion. Cell phones, PDAs, and laptop computers from other companies have also been the source of surprise flames.

A little more than a month before Williams' iPod caught fire, another Georgia man had a close call with his laptop. Douglas Brown's Dell 9200 laptop began to spark while he was using it in his home, and the computer erupted in flames. Brown told ConsumerAffairs.com that "it looked like fireworks, which would have been cool, had it not been in my house" [source: Consumer Affairs].

In 2006, an overhead luggage compartment caught fire on a plane at JFK International Airport in New York thanks to a faulty consumer electronic. This and other similar events prompted the U.S. Department of Transportation to issue a travel warning concerning consumer electronics on planes [source: The Register].

The incidents of electronic devices catching fire are isolated, relatively speaking. But in response to these sporadic outbursts, a number of companies have recalled consumer electronics due to their flammable properties. Millions of laptop computers produced by Dell, Apple and Lenovo have been brought back to the factory and replaced.

So what gives with the flame-ups? It's the batteries. Read the next page to find out why batteries are to blame.

Quite a Charge

A lithium-ion battery
A lithium-ion battery

The reason behind all of the flame-ups has been traced back to the lithium-ion batteries commonly used in products like laptop computers, cell phones and, yes, iPods. Sony has recalled around 10 million of their batteries at a cost to the company of more than $400 million. Apple hasn't confirmed that the source of Danny Williams' iPod Nano fire was the battery, but the Nanos do use lithium-ion batteries.

So what's the problem with the batteries? Do they run on gasoline?

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HowStuffWorks has already addressed the flaming batteries found in some laptops, and has explained how lithium-ion batteries work (it turns out that they don't run on gas). Declaring lithium-ion batteries as potentially hazardous is not new. So why do consumer electronic companies use them?

The answer is because the batteries give a lot of bang for the buck. They can hold up to six times the charge of a regular lead-acid battery (like the kind used in a car) for the same amount of battery weight, which makes them very valuable for making mobile devices like cell phones and laptops lighter. They are also rechargeable. The problem with lithium-ion batteries is that they degrade over the course of a few years. As the batteries degrade, the lithium and carbon that create the charge also degrade, and impurities form.

Sony says that the battery fires are caused by microscopic metal particles that come in contact with the other parts of the battery cell, causing a short circuit. The company says that on most occasions, the battery will shut down when a short circuit occurs. In some instances, however, the short circuit will cause an overheating of the battery cell, which could then erupt in flames [source: Sony].

Flaming consumer products add up to more than just threatened lives, lawsuits, recalls and lost revenue. It also further illuminates a painful fact that is well-known in the tech industry: Battery technology has not been able to keep up with the rapid progress of consumer electronics. As iPods get smaller, laptops get lighter, and cell phones get slimmer, the designs of these products are still held back by the bulky -- and, at times, dangerous -- batteries they use. This puts the tech industry in a catch-22: We live in an increasingly wireless world. Companies that produce wireless devices are forced to use batteries, and currently the best batteries for mobile devices are lithium-ion.

This catch-22 has spurred vigorous research into finding an improved battery technology. It has become a Holy Grail of power supply research in recent years. The company that can manufacture a lighter, safer, longer-lasting battery could take over the lion's share of the market. This is no secret, and many groups are competing to find a way to break through the battery barrier.

Read the next page to find out about a few of the projects that are being carried out to find the next generation of batteries.

Battery Breakthroughs?

World, meet Shewanella oneidensis, possibly­ your next battery.
World, meet Shewanella oneidensis, possibly­ your next battery.

In the search for a better battery, researchers are trying everything they can think of. One team of researchers at the Massachusetts Institute of Technology is looking at capacitors, a type of electricity generator that dates back 300 years. Capacitors don't store as much of a charge as batteries, but they can be recharged in a few seconds, as opposed to the hours it takes rechargeable batteries to power up. Capacitors can also be recharged hundreds of thousands of times, which vastly extends their life over lithium-ion batteries.

The reason capacitors have fallen out of use is that they require a large surface area to power a device such as a laptop. The MIT researchers have gotten around this by applying nanotechnology to the capacitor. Nanotechnology uses incredibly small materials -- the MIT scientists are using nanotubes, which are 30,000 times thinner than a human hair [source: Science Central].

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By expanding the amount of matter within the capacitor surface on a nanoscale, the researchers were able to give the capacitor the power required by mobile devices and electric cars, while reducing the surface area needed to generate the electricity.

MIT isn't the only institution taking another look at the capacitor. A team at LG Chemicals has created a hybrid of rechargeable battery and capacitor that is lightweight and biodegradable. The battery can store energy, and the capacitor releases that energy safely in large, predictable amounts. But the plastic battery is still under research, and in its current form won't make it to the market -- it can only hold about the same charge as a traditional alkaline battery, like the ones that power your point-and-shoot digital camera.

The LG battery does have an extra bonus in addition to its biodegradable property. It can be molded into any shape, which means that mobile device designers would no longer have to create a product based first on the size and shape of the battery it uses [source: Brown Daily Herald].

Batteries of all stripes traditionally rely on chemicals to create their charge. But research into a new type of battery uses more organic substances. In 2006, the U.S. Air Force granted $4.5 million to a University of Southern California-based research team to continue its investigation into using microbes as a power source. In the late 1980s, researchers discovered that the Shewanella oneidensis MR-1 bacteria naturally generates electricity, and since then, science has been searching for a way to harness its power and apply it to practical applications. The USC researchers have created a microbial fuel cell using the MR-1, but it's only been able to produce a weak current so far. The Air Force funding should help ensure that the researchers will continue their investigation, however [source: Physorg.com].

Regardless of what technology is employed in the battery of the future, it must possess at least three properties: It must be lightweight, it must be long-lasting, and -- perhaps most importantly -- it must not catch fire.

For more information on batteries and fire, read the next page.

Related HowStuffWorks Articles

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Sources

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