Wednesday, August 23, 2006

Lithium Laments

Right now, Michael Dell is probably wishing he'd never heard of lithium. After Dell Inc. recalled over four million laptop batteries on Aug. 14 in the largest consumer-electronics recall ever, the New York Times sent out a photographer to Lake Mead to get a picture of one Thomas Forqueran looking at the gutted and smoky interior of his pickup truck. He had stored a Dell laptop in the glove box next to some ammo, and when the laptop battery caught fire, the ammo went too. Fortunately, Mr. Forqueran was not in the truck at the time.

The culprit in this case was a faulty lithium battery manufactured by Sony. Why is it that lithium batteries are so dangerous? Why did the National Transportation Safety Administration prohibit cargoes containing lithium batteries on passenger planes back in 2004, and why was a shipment of lithium batteries in a UPS plane suspected as the cause of a fire last February that destroyed the plane? Basically, for the same reasons that lithium is used in batteries at all.

Batteries store energy in the form of chemical compounds. The more energy you can store in a give size and weight of battery, the longer the battery can power a device such as an iPod or a laptop. Electrochemical reactions with lithium provide more voltage than almost any other single reaction, and lithium is the lightest known metal. For these and other reasons, battery makers have been using lithium in their latest and greatest products.

But for many of the same reasons that make lithium attractive for batteries, it is a nasty element to handle. If you throw pure lithium into water, it will spontaneously catch fire and give off noxious fumes. This makes it hard to battle fires involving lithium, needless to say. Even throwing sand or using CO2 fire extinguishers doesn't work—burying the fire in table salt or lime are about the only things that work. The lithium compounds used in rechargeable batteries are also hazardous, and can catch fire even if slightly contaminated by moisture. Once a lithium battery overheats and starts to burn, it tends to feed on itself as the cell ruptures and the lithium gets into contact with more material it can react with. What apparently happened with the Sony batteries is that a flaw in the manufacturing process left small metal particles in the wrong place. Mechanical stress on the battery once it was installed may have moved these particles around to short out the battery, creating enough heat for it to catch fire.

There are several lessons here. First, as we demand more and more from our portable electronics, we are also asking for more and more energy to be packed into batteries. On the horizon are fuel-cell batteries that run off propane or gasoline. Theoretically, one of these could run your laptop for days between fillups, but then there's the price of gasoline to worry about, not to mention the potential for leaks or spills. So there will be more battery hazards to watch out for if manufacturers don't enforce rigorous quality controls at every step of the way.

Next, it is unclear how long Sony had the manufacturing problem before fires started to occur. As engineer and author Henry Petroski likes to say, engineers often learn a lot more from failure than success. This emphasizes the importance of analyzing failures of products in the field until the engineers know exactly what caused the problem, and exactly how to fix it. But none of that can occur without good communication among vendors, suppliers, repair facilities, salesmen, and others.

This writer recalls an incident he heard about many years ago, when he was working for a large communications company which shall remain nameless. The company made the amplifiers for cable TV systems, metal boxes that hang on telephone poles and keep the cable TV signal strong enough to travel several miles between the "head-end" and the homes that take cable TV service. It seems that after several hundred of these amplifiers were shipped, they all started to fail in the same way. The circuit chip that was the heart of the amplifier was mounted to a metal heat sink, and when the engineers back at the plant opened up the failed amplifiers, they found that somehow the chips had separated from the heat sink, which caused them to burn up.

The engineers had been using this type of chip for some time in other products, and so they went back through the repair records to see if there had been any similar problems earlier. Sure enough, the problem began to show up several years before, but then it seemed to disappear—no more records of that kind of repair. The engineers called up the technician who had signed the failure reports and asked him what had happened at the point when the failures stopped occurring.

"Oh, we kept getting busted amps like that," he replied. "There was just so many of 'em, I got tired of filling out the same old failure report."

One hopes the quality-control system at Sony operates better than that. But any organization is only as good as the people in it, and if only one critical person fails to follow the procedure that others are expecting, the whole system can fail.

We can be glad that there have not been any reported fatalities resulting from flaming Dell laptops. Dell as a company will probably survive this incident. But a safety recall like this can ruin a small or new company's reputation permanently and put it out of business, even if no one is hurt. The daily routines of reliability engineering, quality control, and other related technical and managerial jobs can seem boring or even pointless at times. But like police patrols, they protect the safety and welfare of the public, and negligence in these areas can lead to disaster.

Sources: The New York Times article on the Dell laptop battery recall is at The NTSB notice prohibiting passenger planes from carrying cargoes of lithium batteries is discussed at The UPS plane fire is reported in TG Daily at

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