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The topic of exploding lithium-ion batteries has been debated to death in the wake of massive battery recalls over the last couple of years. Amidst the deft public relations maneuvering and finger-pointing, however, the question as to why they explode in the first place is still shrouded in mystery for many.

The most important thing to understand here is that lithium-ion technology is considerably more volatile compared to other forms of rechargeable battery technologies. Defects in the insulating membrane can result in a mini-explosion that rips a battery open to release steam in excess of 600 degrees Fahrenheit.

Manufacturers are aware that it is statistically probable for a lithium-ion to fail, though the calculations employed to sideline the risk are sometimes quite suspect. To determine the mean time between failures (MTBF), manufacturers take a sample of say, 1,000 batteries, which are then used until one fails.

Assuming that the battery that died did so after 100 hours, the MTBF for that batch is pegged at 100,000 hours, or 100 multiplied by 1,000. While satisfying to the QC manager, it is completely meaningless to the consumer. A MTBF of 100,000 hours implies that the battery will work for more than 10 years. This is false; because lithium-ion cells starts deteriorating the moment they are manufactured. On the shelf in a fairly hot warehouse, a fully charged lithium-ion battery could irreversibly lose up to a third of its maximum capacity in just one year.