Overheated laptop batteries a fire hazard
It can be dangerous to take a laptop to bed and go to sleep without shutting it down.
New Delhi: Owning a laptop may have become a necessity for some and fashionable for the rest, but it poses a potential fire threat to thousands of users who prefer to take the device to bed and go to sleep without logging off, as was seen in the recent death of a Kolkata-based executive.
Sayan Chowdhury, a 34-year-old MNC employee, was found dead in his bedroom November 6, where he had dozed off while working on his laptop. The laptop and the charging cord were found partially burnt.
According to the autopsy report, he lost his life either because of overheating of the battery which caused a fire, or electrocution or carbon monoxide poisoning.
This incident bears an uncanny similarity with the case of 25-year-old Arun Gopalratnam, an MBA graduate, who died June 4, 2010 in a tragic fire in Wisconsin, US. The blaze was reportedly caused by his laptop when it overheated on his bed while he slept, because it had not been logged off.
Investigators found that the laptop's positioning on the bed had cut off air from its cooling fan, overheating the set, which sparked the fire and produced carbon monoxide, killing Gopalratnam in his sleep.
Similarly, an overheated laptop also killed a 56-year-old man in Vancouver, Canada. The unnamed man fell asleep with the computer still logged on. His laptop's placement on the bed had cut off its source of ventilation, causing the lithium ion battery, a relatively new technology, to overheat and burst into flames that proved fatal for him.
Being lightweight and portable, users prefer to take their laptops to bed to work, surf the net or watch movies, until they fall asleep in the wee hours without logging off, even as the batteries overheat and start a fire. Experts advise people to avoid this practice.
"Bottom line is that we take things for granted. We feel safe putting a device that pushes 19 volts and holds many harmful chemicals on the lap. We put a potential grenade next to our eye, hoping it won't go up in flames," writes US gadget expert, technical consultant and blogger Jeffrey Powers.
"If your battery is dead, replace it. Charging a dead battery is like continually trying to light a fuse that is soaked in water. Eventually, it will spark," he adds.
Almost invariably, lithium batteries seem to be a major factor in exploding laptops because of certain limitations, which had necessitated companies like Dell, Sony and IBM to recall a series of batteries in the past.
"The only thing you can do if your laptop heads into flames is...don't throw water on it. Remember, this can create a fire hotter than a standard fire," advises Powers.
"A Class D fire extinguisher will help stop the fire. Try to use something to push it into a trash can or something non-flammable. Keep the laptop plugged into a surge strip - that way if the fire breaks out, the surge protector trips," says Powers.
A Class D fire is one that involves combustible metals or combustible metal alloys. There are basically two types of Class D fire extinguishers. It is the second variant that uses a copper based dry powder - the only known lithium fire fighting agent - which can put out laptop flames.
The current drive towards more compact laptops also downsizes ventilation to manage heating, just as slimmer batteries raise chances of a short circuit from a punctured separator, a membrane that separates the positive and negative charges in a battery. DVD players built into laptops too add their share of heat.
Lithium in laptop batteries is a highly reactive metal that can burn or explode simply by being exposed to air or water. It is present in a flammable liquid which surrounds a metal coil inside the battery. As this liquid heats up, it flows like water in a radiator, carrying metallic particles.
One of them can pierce the separator, triggering a short circuit that ignites the flammable liquid or generates greater heat and pressure, which end in a leak or an explosion.