Lithium batteries power many of the gadgets we rely on each day – from lawnmowers and phones to phones – but if not stored, charged or discarded properly they could cause fires.
FDNY responds daily to battery-related fires caused by individuals failing to follow proper storage, charging and disposal procedures for batteries.
Electrical Short Circuit
Lithium-ion batteries are widely used consumer tech products and provide long battery life for smartphones, cameras and laptops. Furthermore, lithium-ion batteries make an excellent option for large energy storage systems as well as electric vehicles; however, manufacturing issues and misuse may increase their fire risk due to use of flammable materials in their construction.
Electrical short circuits occur when there is an unintended and low resistance connection between two conductors that supply power to an electronic device, generating excess current that could damage or cause fire damage to it. Thankfully, safety devices like fuse boxes and circuit breakers exist to help prevent electrical short circuits by breaking the circuit when excessive current levels are detected and disabling it before any more damage can occur.
Unfortunately, these safety measures are not sufficient to prevent all electrical short circuits. Short circuits may occur due to factors like pests chewing wires, exposed electrical wiring being exposed to moisture or overcharging batteries.
Many electrical short circuits that lead to battery fires are the result of overheating. When this occurs, heat builds up faster than it can dissipate from within the battery and eventually causes explosion or fire to ensue.
Electrical short circuits may be extinguished with water in some instances; however, major battery fires often require something different as lithium salts cannot be starved of oxygen – this makes using traditional fire extinguishers impossible in these instances.
Although companies and consumers strive to reduce lithium-ion battery fire risks, some incidents do still happen. Therefore, facilities with large quantities of these batteries or energy storage solutions need to develop plans to safely dispose of, charge, and store these batteries as part of an energy storage solution. In addition, facility managers must collaborate with fire protection contractors in putting into effect adequate prevention measures that will protect these facilities from lithium-ion battery fire risks.
Thermal Runaway
Lithium-ion batteries power everything from electric vehicles and portable devices like smartphones and portable music players to smartphones themselves. While lithium-ion batteries tend to be safe and reliable, in certain conditions they may experience thermal runaway.
Thermal runaway is a process that can lead to battery fires and explosions. This chain reaction begins when one cell reaches a critical temperature and triggers chemical reactions that generate more heat, rapidly raising internal battery temperatures until they reach the point of no return, at which point fire or explosion may result.
Thermal runaway remains poorly understood; however, we know it can be caused by both internal and external factors. Manufacturing defects, excessive mechanical abuse such as crushing or puncturing of batteries, exposure to elevated temperatures and overcharging all play a role. Overcharging can increase heat production within batteries further contributing to thermal runaway.
Once thermal runaway has begun, it can be extremely challenging to stop. As internal temperature of battery increases and releases flammable gases into the atmosphere, creating an extremely dangerous situation for workers and equipment alike. Therefore, it’s crucial that lithium batteries be kept safe with an appropriate storage cabinet designed to prevent fire outbreak and extinguish quickly in case it’s necessary.
Battery cabinets should be constructed of double-walled steel construction with at least 40mm of space between walls, featuring self-closing doors to reduce thermal runaway risks and an internal cooling system, along with venting features to release gases when they become under pressure.
To reduce thermal runaway, it is best not to charge your batteries close to their maximum capacity. Doing so will shorten their charging state time and potentially lower working life, increasing risk of overcharging and potentially shortening working life as well. For best results, storage temperatures between 20degC and 25degC should also be adhered to when keeping batteries stored away for long-term.
Smoke & Swelling
Fire departments across New York City have seen an upsurge in battery-related incidents due to the surge in popularity of electric bikes and scooters, such as those powered by lithium-ion batteries. Although many factors contribute to these fires, lithium-ion batteries play an outsized role.
EV and ESS battery fires can be difficult to extinguish, often continuing burning hours or days after initial flames have been put out. Thermal runaway is usually to blame; this phenomenon occurs when cells in a lithium-ion battery overheat too fast for dissipation; it could happen from overcharging, an overheated charger, cell damage with ruptured cells that release flammable vapors, overcharging etc.
Lithium-ion battery fires are difficult to extinguish due to their quick burning rates and toxic off-gases that pose risks to both people and animals. Their unique chemical makeup renders them resistant to certain fire fighting methods like water. As a result, risk managers should consult a fire protection engineering organization such as TUV SUD Global Risk Consultants when developing safe processes at facilities that store large quantities of lithium batteries or energy storage systems.
The best way to prevent battery fires is by keeping them cool, dry and away from heat sources. In addition, only using approved EV chargers and never connecting multiple devices into one outlet are essential to protecting EVs and ESS banks against electrical short circuits, another common cause of battery fires.
When a battery ignites, it is crucial that it be immediately removed from its surroundings and evacuated immediately. Water or foam should never be used as dousing agents as this will only fuel it further; fire professionals typically utilize water from a safe distance using a hose nozzle in order to control flames and dissipate harmful off-gases from off-gassing systems.
Battery Combustion
Lithium-ion batteries that become overheated and overcharged can enter an extreme state known as thermal runaway. As their internal temperatures rapidly increase, decomposing materials begin to generate exothermic reactions that release an enormous amount of heat that cannot be dissipated through conventional means – leading to fires caused by lithium batteries that are often devastatingly destructive.
As temperatures inside of a battery increase, its materials may begin to overheat and overcharged cells can begin to overheat and ignite – sparking more to do the same until all batteries in a pack have caught fire. For this reason, lithium-ion batteries that show visible signs of damage or overheating should never be used again.
Chain reactions like these often contribute to fires that erupt in dense apartment complexes and storefronts, as well as to many battery fires traced back to replacement batteries without an Underwriters Laboratories label, or chargers that do not stop charging when their charge has finished.
Unfortunately, battery fires can typically be extinguished with water alone; however, this process may take time and still poses the possibility that battery or environmental charges reignite causing more harm than good. Williston Fire advises the safest solution is not charging at all and following manufacturer guidelines to the letter.
Recently, researchers used puncturing a single battery cell to demonstrate the speed with which combustion of batteries can spread across adjacent cells in minutes. As seen on video footage captured by researchers, when one cell overheated and ignited it only took four minutes before overheating began in another battery and its ignition.
Researchers conducted experiments to observe what happens to fully charged batteries at different states of charge (SOC), and discovered that their ability to contain inner reactions decreases as SOC does, leading to faster rates of combustion as SOC goes up. They suggested using thin foam sheets as covers on batteries in order to slow this process and lessen risks of fire, explosion and injury.