Lithium Batteries Keep Exploding

Samsung lost $5.3 billion on the Galaxy Note 7. All 2.5 million devices recalled after batteries caught fire. Both problems caused internal shorts. Both caused fires.

That was 2016. The industry promised better quality control. Better testing. Safer designs.

New York City counted 18 deaths from e-bike battery fires in 2023.

How Thermal Runaway Works

A lithium-ion cell stores energy by moving lithium ions between electrodes through an electrolyte, a flammable organic solvent. A thin plastic separator keeps the electrodes apart. Breach that separator, and current flows directly between electrodes. Heat builds.

Past 150°C, the electrolyte starts decomposing. Decomposition releases more heat. More heat accelerates decomposition. The reaction feeds itself, generating temperatures above 600°C and releasing oxygen that sustains combustion even in sealed containers.

Pressure rises until something gives.

Most cells just vent hot gas. Some catch fire. A few explode violently enough to send metal fragments across the room.

The Note 7 Wasn't Special

Apple recalled MacBook Pros in 2018 for the same basic problem, batteries prone to overheating during charging. The FAA banned certain models from flights the following year.

GM recalled every Chevrolet Bolt ever made, 141,000 vehicles, after identifying manufacturing defects in LG Chem cells that could cause internal shorts. Replacing all those battery packs cost $2 billion. The largest single-component recall expense in automotive history, for a defect that could have been in any of the vehicles from the start.

Tesla vehicles have caught fire while parked, while charging, and especially after crashes. A Model S that crashed in Florida in 2018 reignited twice after firefighters thought they had extinguished it. The NTSB found first responders had no training for these scenarios. Their equipment assumed fires could be suppressed. Battery fires cannot run on their own oxygen until the reactive material is exhausted.

The Arizona Public Service explosion in 2019 injured four firefighters when they opened a container housing a grid-scale battery system. Hydrogen had accumulated inside due to poor ventilation. Introducing oxygen triggered ignition. The blast threw a 30-ton door 70 feet.

South Korea recorded 23 energy storage fires between 2017 and 2019. Investigations blamed defective management systems, installation errors, environmental exposure. Billions in damage. The grid-scale battery industry had scaled up faster than safety engineering could keep pace.

UPS Flight 6 crashed in 2010 after lithium battery cargo caught fire in flight. Both pilots died. The FAA has documented over 400 battery incidents on commercial aircraft since then: phones igniting in passengers' pockets, laptops smoking in overhead bins, power banks overheating mid-flight. Airlines now enforce strict controls. Spare battery limits. Bans on damaged or recalled cells. Certain laptop models prohibited entirely.

These are not anomalies from a single bad manufacturer or a particular application. Phones, laptops, cars, grid storage, cargo aircraft: the failure mode stays the same. Something goes wrong inside a cell. Thermal runaway follows.

Why Quality Control Fails

Manufacturing lithium batteries requires extreme precision. Microscopic metal particles contaminating the separator can create short circuits. Electrode alignment matters. Moisture causes degradation. Contamination during any step (mixing, coating, assembly, sealing) can create cells that will eventually fail.

But a defect that will eventually cause thermal runaway might not be detectable when the battery leaves the factory. A particle too small to see on inspection might not cause problems for months. The cell passes every test, ships, works normally, then shorts.

Testing every cell thoroughly enough to catch hidden defects would make mass production uneconomical. X-ray inspection helps. Pressure testing catches some defects. Electrical testing identifies cells with immediate problems. But a cell with a contamination particle embedded harmlessly in the separator, positioned where it will slowly migrate to cause a short in six months, passes all of these.

Manufacturers test samples and trust statistics. At failure rates of one in a million, the math looks acceptable. At production volumes of billions of cells per year, one in a million means thousands of failures annually.

Raw material costs add pressure. Lithium, cobalt, nickel: prices fluctuate, supply chains stretch across continents, margins are tight. Battery packs represent 30-40% of an electric vehicle's total cost. Pressure to cut costs translates to pressure on tolerances, testing protocols, quality control staff.

The Degradation Problem

Every charge cycle damages a lithium battery slightly. Lithium ions moving back and forth between electrodes causes gradual structural damage to electrode materials. Side reactions consume active lithium. The solid-electrolyte interface layer thickens.

After two or three years, capacity loss becomes noticeable: the phone that used to last all day now needs charging by dinner. After five to seven years, most lithium batteries are ready for replacement.

But degradation affects safety margins as well as capacity. Dendrites, branching metal structures, can grow inside aged cells, eventually piercing the separator. Internal resistance increases, generating more heat during charging. Electrode materials become more reactive as their structure degrades.

An aged battery may enter thermal runaway under conditions a new battery would tolerate.

Heat accelerates all of these processes. A laptop left in a hot car degrades faster. A phone charged while running intensive applications degrades faster. The battery management system can limit charge rates and temperatures to slow degradation, but cannot prevent it entirely.

E-Bikes in New York

The 268 e-bike battery fires New York recorded in 2023 killed 18 people. More than any other single fire cause that year.

Most followed a pattern: cheap bike purchased online, charged overnight in an apartment, thermal runaway sometime before dawn. Fire blocks the exit. Smoke fills the unit before anyone wakes.

The bikes cost a few hundred dollars. At that price point, the batteries come from manufacturers with minimal quality control, no sophisticated thermal management, no reliable battery management systems.

Some buyers replace original batteries with higher-capacity aftermarket packs designed without proper engineering. Others use chargers not matched to their batteries. The combination of cheap cells, inadequate protection circuits, and improper charging creates the conditions for thermal runaway.

The apartments where these fires occur tend to be small, with limited escape routes. Residents charge bikes overnight because that is when they are home and not using them. Fires that start at 3 AM have hours to spread before discovery.

Delivery workers rely on e-bikes for income. Multiple batteries and extended charging sessions are normal. The economics push toward cheap equipment used intensively, charged frequently, replaced when it fails rather than when it ages.

The regulatory response has been fragmented. Some jurisdictions require permits. Some ban indoor charging in multi-unit buildings. Some mandate that batteries meet specific safety standards (UL 2271 for battery systems, UL 2849 for complete e-bikes) but enforcement is spotty and many devices on the market were imported before any standards applied.

Hoverboards went through a similar cycle in 2015 and 2016. Cheap devices with cheap batteries caught fire in homes, stores, airport terminals. Airlines banned them. The Consumer Product Safety Commission issued recalls. The product category collapsed.

E-bikes are more useful than hoverboards, and the people who depend on them for work have fewer alternatives. The fires will likely continue.

What Firefighting Looks Like Now

A gasoline fire can be knocked down in minutes with standard equipment. Fuel burns off. Fire goes out.

Lithium battery fires sustain themselves. The reaction generates its own oxygen from electrolyte decomposition. Water cools surrounding structures but does not stop the battery; it continues burning until the reactive materials are exhausted.

A single EV fire can require 10,000 gallons of water applied over hours. Batteries reignite after appearing extinguished, sometimes hours later, sometimes days. The Tesla that crashed in Florida reignited twice at the scene, was towed to a storage lot, and caught fire again there.

Fire departments have rewritten protocols. Some carry blankets that contain battery fires while they burn out. Others keep containers that can submerge burning batteries for extended cooling. The goal has shifted from suppression to containment: let the battery burn itself out while protecting surrounding structures.

First responders need specialized training to identify lithium battery fires and understand their behavior. Protective equipment rated for the toxic gases released during thermal runaway. Knowledge that opening an enclosure might introduce oxygen that triggers explosion rather than enabling suppression.

Most departments received none of this training before lithium battery fires became common. Catching up takes time and resources that not all departments have.

Building Codes Were Written for a Different Era

Most residential and commercial building codes were written before anyone expected large battery systems in residential garages or e-bikes charging in apartment hallways.

Home energy storage systems pack 10,000 watt-hours or more into units installed in garages and basements. A thermal runaway event releases that energy in minutes, enough to ignite surrounding structures before occupants realize what is happening. Ventilation may be inadequate for the gases released. Fire suppression is usually nonexistent.

Some jurisdictions now require permits for home energy storage installations. Others mandate outdoor-only installation for systems above certain capacities. Fire suppression systems are required in some areas. Minimum setback distances from sleeping areas have been implemented in others.

Most jurisdictions have done nothing. The technology deployed faster than codes could adapt, and updating building codes is a slow political process involving multiple stakeholders with competing interests.

Apartment buildings face different challenges. E-bikes and scooters charge in hallways, living rooms, bedrooms. Fires block egress routes before residents can react. Building-wide bans on indoor charging are hard to enforce when residents need the devices for their livelihoods.

Insurance Hasn't Caught Up Either

Homeowner policies were not written anticipating 10-kilowatt-hour battery systems. Commercial policies did not account for warehouses full of e-bikes or EVs creating concentrated fire risk.

Some insurers now exclude battery fires from coverage entirely, language buried in policy updates that many homeowners never notice. Others charge substantial premiums for properties with energy storage systems. Electric vehicle coverage is evolving, with questions about whether standard auto policies adequately cover the unique risks and expensive battery replacement costs involved.

Liability for battery fires remains legally unsettled. When a battery fire destroys a house, does responsibility fall on the cell manufacturer, the pack assembler, the device maker, the seller, the installer, or the owner? Different jurisdictions are reaching different conclusions. Lawsuits drag on for years.

The LG Chem cells in the Chevrolet Bolt (the same cells that caused billions in recall costs for GM) were also used in home energy storage systems. Homeowners who installed those systems expecting to save on electricity bills and reduce their carbon footprint found themselves wondering whether the device in their garage might burn their house down.

Shipping and Warehouses

Lithium batteries are classified as dangerous goods for transportation. Airlines, shipping companies, and ground carriers all face regulations specifying packaging, labeling, quantity limits, and handling procedures.

The regulations exist because cargo incidents keep happening.

Warehouse fires involving stored batteries have destroyed facilities and inventory. Consumer electronics contain batteries. Power tools contain batteries. Toys, medical devices, personal care products: batteries are everywhere, and concentrating large quantities in warehouse storage creates risk that individual product packaging was not designed to address.

A single cell entering thermal runaway can propagate to adjacent cells. In a warehouse full of battery-containing products, propagation can cascade across racks and aisles.

Shipping lithium batteries by sea has its own challenges. Container ships carry thousands of containers across weeks-long voyages. A fire at sea has limited response options. Ships have been lost to cargo fires where batteries were suspected or confirmed as the ignition source.

Air cargo presents the highest stakes. UPS Flight 6 demonstrated what happens when battery cargo ignites in flight. Since then, regulations have tightened: quantity limits, packaging requirements, position in the aircraft. But lithium batteries still fly in passenger baggage, in checked luggage, in belly cargo.

The volume is enormous. Every smartphone, every laptop, every tablet, every wireless headphone, every power bank, every piece of battery-powered consumer electronics moving through global supply chains contains cells that regulations treat as hazardous materials. Inspection and enforcement resources cannot scale to match.

Medical Devices and Vaping

Batteries in medical equipment present a different kind of risk: the people affected often cannot escape quickly.

The FDA tracks medical device battery failures. The reports include wheelchairs catching fire while patients sat in them. Insulin pumps igniting. Portable oxygen concentrators overheating, devices that operate surrounded by concentrated oxygen, which accelerates any combustion.

Pacemaker batteries have caused internal thermal events. The patients survived, but the device that was supposed to keep them alive became a source of harm.

These incidents get less media coverage than phone fires or EV recalls. They affect fewer people in total. But each one represents someone who depended on battery-powered equipment for mobility, medication delivery, or life support, and whose equipment became dangerous.

The common scenario: aftermarket batteries or chargers not designed for the device. Higher-capacity cells pushed beyond their limits. Damage from dropping that goes unnoticed until the battery shorts internally.

Safer Batteries Exist

Lithium iron phosphate cells offer better thermal stability than the lithium-cobalt chemistry in most consumer electronics and many EVs. The tradeoff is lower energy density: heavier batteries for the same capacity, or less capacity for the same weight.

Some EV manufacturers have shifted to lithium iron phosphate for standard-range models. Phones and laptops continue using lithium-cobalt because consumers expect thin, light devices with long battery life. The chemistry that maximizes those properties is the chemistry that burns most violently when it fails.

Solid-state batteries replace the flammable liquid electrolyte with solid material, eliminating one component of the fire triangle. Commercial production at scale remains years away. Manufacturing costs are high. Cycle life and performance under real-world conditions are still being proven.

Improved battery management systems can detect problems earlier and disconnect cells before thermal runaway begins. But a defective cell that develops an internal short may bypass the management system entirely: the short is inside the cell, not in the connections the management system monitors.

The market has not shown much appetite for trading performance for safety. Phones keep getting thinner. EV range keeps climbing. Energy density keeps increasing.

End of Life

Lithium batteries present disposal challenges beyond the fire risk during use.

Recycling is technically possible but economically marginal. Cells must be discharged safely: residual energy remains even in "dead" batteries, enough to cause thermal runaway if processing goes wrong. Disassembly requires care. Sorting by chemistry matters for downstream processing. Specialized facilities are scarce.

Most lithium batteries end up in landfills. The first generation of mass-market EVs is approaching end of life, and the industry has not solved what to do with millions of large battery packs that cannot be economically recycled.

Mining the raw materials (lithium from salt flats, cobalt from central African mines, nickel from wherever it can be sourced) carries its own environmental costs. Processing requires substantial energy. The "clean energy" framing around EVs and battery storage slides past these impacts.

The lifecycle accounting is complicated. Displacing gasoline emissions matters. So do the emissions from battery production. The mining damage. The disposal problem. Whether the net is positive depends on assumptions about grid mix, vehicle lifespan, and what alternatives would otherwise exist.

The Numbers That Matter

Billions of lithium-ion cells are deployed: in pockets, on nightstands, in garages, in vehicles. Production volumes continue growing as applications expand.

Failure rates have declined from early generations of the technology. Better manufacturing processes, better quality control, better management systems. But "declined" does not mean "zero," and as the number of cells in circulation grows, the absolute number of failures grows with it.

A failure rate of one in ten million looks acceptable until production hits ten billion cells per year.

The consequences of failure are not evenly distributed. E-bike fires concentrate in low-income urban areas where residents charge cheap devices in cramped apartments with limited exits. The eighteen dead in New York in 2023 were not randomly selected from the population.

Warehouse workers face concentrated exposure when battery-containing products fill the facilities where they work. First responders face risks their training and equipment did not prepare them for.

Grid-scale storage facilities are typically sited away from population centers, but the workers who maintain them and the firefighters who respond when something goes wrong bear the immediate risk.

No Real Conclusion

The industry points to declining failure rates and improved safety systems. Emergency responders point to the incidents that keep happening and the tools they lack to address them. Regulators point to updated codes and standards that lag years behind deployment. Insurance actuaries point to claims data they are still trying to understand.

E-bike fires in New York killed 18 people last year. That number will likely increase as the devices become more common.

The Chevrolet Bolt recall cost $2 billion. GM absorbed it. Other manufacturers are watching their own battery supply chains and hoping their cells do not have similar defects waiting to manifest.

Airlines carry lithium batteries on every flight, in passengers' pockets and checked baggage and cargo holds. The FAA's incident database keeps growing.

The technology is here. The risks are here. The market has made its choices.