by Dave Soulia, for FYIVT.com

Videos of electric bicycles, power banks, tools and electronic devices erupting into flames have become a regular feature on social media. In many cases the battery does not appear to be charging or even in use. It is sitting on a counter, attached to a bicycle or stored inside a building when smoke appears and the device catches fire.

The incidents can make lithium-ion batteries look like random time bombs. The mechanism is better understood than that, though not entirely reassuring: a battery can sustain internal damage long before any visible sign of failure appears.

A Large Amount of Energy in a Small Package

Lithium-ion batteries store substantial energy while remaining small and light. They power phones, laptops, cordless tools, electric vehicles, power banks, bicycles, scooters and home energy-storage systems.

Inside each cell are two electrode materials separated by an extremely thin barrier. The separator lets charged ions move while keeping the electrodes from touching. The cell also contains an electrolyte that can burn.

According to UL Solutions, the thinness of that separator makes it a failure point when there is a manufacturing defect or damage during handling and use. A failed separator allows an internal short circuit, and the heat it produces can drive the cell into thermal runaway, an uncontrollable self-heating state. UL says thermal runaway can generate elevated temperatures, fire and the ejection of gas and shrapnel, and that the heat can push neighboring cells into thermal runaway as well.

Why Batteries Sometimes Ignite While Idle

A battery does not have to be plugged in to catch fire. The Environmental Protection Agency notes that batteries can hold enough energy to injure or start fires even when they appear to be discharged.

UL lists the causes of internal short circuits as mechanical abuse — drops, crushing, impact, vibration — along with manufacturing contamination, bad welds, abnormal temperature or pressure, and progressive internal damage from improper charging and discharging.

That last category is the one that produces surprises. A cell can keep working after the initial damage while a small internal short develops, until localized heating degrades more of the separator and the cell reaches a temperature at which failure accelerates.

The U.S. Fire Administration lists overcharging, overheating and ordinary charge-cycle aging among the conditions that lead to dangerous incidents, and notes that a lithium-ion battery fire can reignite after it appears to have been extinguished.

In July 2026, the Consumer Product Safety Commission warned consumers to stop using METASONO/MEATSONO heated insoles because the internal lithium-ion battery could explode and ignite even when the insoles were turned off. CPSC cited 14 reports of fires, explosions and other thermal incidents and at least 10 burn injuries, including second- and third-degree burns requiring skin grafts.

Recalls Are Not Limited to Unknown Brands

Lower-quality cells, counterfeit replacement batteries and poorly designed charging systems draw obvious concern, particularly in inexpensive e-bikes, scooters and power banks. Recalls have also reached established names.

In December 2025, CPSC announced the recall of approximately 210,000 INIU power banks because their lithium-ion batteries could overheat and ignite. INIU had received 15 reports of overheating, including 11 fires, three minor burn injuries and more than $380,000 in property damage. In November 2025, Belkin recalled about 83,500 power banks and charging stands over the same hazard. In April 2026, roughly 8,000 VEEKTOMX mini power banks sold on Amazon were recalled after three reported fires.

In March 2026, CPSC warned consumers to stop using Ridstar Q20 and Q20 Pro e-bikes, citing 11 reports of fire, one burn injury, five reports of smoke inhalation and two reports of property damage totaling more than $40,000. The manufacturer declined to agree to a recall.

Volume matters as well. A low individual failure rate becomes visible when hundreds of millions of rechargeable devices are in circulation.

Warning Signs

A failing cell may run hot, swell, change shape, leak, discolor or give off a chemical odor. Hissing, popping or crackling can indicate that a cell is venting or breaking down internally. USFA also lists cracking from a drop or collision and visible gas venting.

Any battery showing those symptoms should be taken out of service, and should not be punctured, crushed or dismantled. EPA advises taping terminals or bagging batteries individually, and says lithium-ion batteries do not belong in household garbage or curbside recycling bins, where damaged cells can ignite inside collection trucks and processing facilities.

Reducing the Risk

USFA’s consumer guidance is to choose certified products, handle them with care, stay alert to changes and recycle properly. It recommends storing lithium-ion batteries at room temperature where possible, not charging them below 32 degrees or above 105 degrees Fahrenheit, and keeping spares away from anything that can burn.

Charging is safer on a solid, noncombustible surface than on a bed, couch or carpet, or near paper, fuel, hay or animal bedding, and chargers designed for the device carry less risk than improvised or counterfeit replacements. A battery that begins smoking or venting should not be carried through a building; occupants should leave, close doors and call 911.

Most lithium-ion batteries operate safely through their service lives. The failures that do occur are concentrated in cells that are damaged, defective, aging or charged outside their limits, and an unplugged battery remains an energized one.