A BBC news story about the dangers of faulty lithium batteries being carried onto aeroplanes features tests carried out in BRE’s fire research labs.
BRE was approached by the BBC’s transport correspondent, Richard Westcott, who asked us to demonstrate how fires can develop in rechargeable lithium batteries. The Civil Aviation Authority (CAA) is concerned about the potential danger posed by these batteries, typically found in phones, cameras and laptops – especially those bought online as low cost replacements.
Using BRE’s fire research Burn Hall, one of the largest fire test labs of its kind in Europe, BRE fire investigations expert David Crowder staged a series of demonstrations showing the scale of fire and explosion that can occur when a lithium battery overheats, by placing the batteries on a carefully regulated laboratory hot plate operating at elevated temperatures.
Overheating can occur in batteries as a result of short circuit (where the metal contacts of the battery become joined by touching other metal items such as keys), or where an internal fault develops in the battery, especially in those sold as budget alternatives online, the manufacture of which may not be so rigorously quality controlled.
Once the batteries reach a critical temperature, an internal chemical reaction causes the lithium content to self-ignite. With two of the batteries tested, both manufacturers’ original parts, the reaction initially produced large amounts of white smoke, and then, some minutes later, ejected flames. On a plane, the smoke would have been clearly visible and it would have been possible to extinguish the fire with a small extinguisher. But, when the ‘copy cat’ non-OEM battery was heated in the same way, it gave little warning smoke and instead exploded, sending metal parts and hot material flying across the test area. This, on a plane or anywhere else, could cause a more serious situation.
To extinguish a lithium battery if it starts smoking, the advice from the CAA is to rapidly cool it using water – for a small battery, simply dropping it in a cup of water, for example. Although live electrical fires should not be extinguished with water, in the case of a battery that is not connected to a device, this is the most effective way of rapidly cooling it and dissipating the thermal energy.
To avoid the risk of fire when transporting batteries, the terminals should be protected, either with the cover supplied with a spare battery, by taping over the terminals, or by placing the battery in a plastic bag to prevent the contacts being shorted. And users should be aware of the potential risks associated with buying budget replacement batteries from the web.