Lithium-Ion Battery Safety Fact Sheet
A plain-language guide for media, safety professionals, and battery users
Lithium-ion batteries power much of modern life. They are found in phones, laptops, power tools, e-bikes, scooters, portable power stations, home energy storage systems, solar battery banks, and many other products.
Most lithium-ion batteries work safely when they are designed well, used correctly, charged with the right equipment, and kept in good condition. But when a battery fails, the event can move quickly. A failure may begin inside the battery before smoke, flame, or obvious heat is visible.
This fact sheet explains the basic safety concepts behind lithium-ion battery risk, why earlier warning matters, and what people can do to reduce risk in homes, garages, workplaces, charging areas, and battery storage environments.
Quick Facts
Lithium-ion batteries can overheat, catch fire, and cause explosions under certain failure conditions. FSRI notes that lithium-ion battery-powered devices are now widely used across everyday products, including phones, laptops, power tools, electric vehicles, and scooters.
Thermal runaway can happen when a battery is damaged, overheated, exposed to water, overcharged, improperly packed, or affected by a manufacturing defect. The FAA notes that lithium-ion batteries are capable of overheating and entering thermal runaway under several conditions.
In a 2025 CPSC draft proposed rule package on micromobility products, CPSC identified 227 incidents from 2019 through 2023 involving fires, explosions, gas releases, burns, overheating, or smoke inhalation associated with lithium-ion batteries used in micromobility products. Those incidents were associated with 39 fatalities and 181 injuries.
FDNY reported 277 lithium-ion battery fires in New York City in 2024, compared with 268 in 2023. FDNY also reported that lithium-ion battery-related deaths fell from 18 in 2023 to six in 2024 after expanded public education, inspections, and outreach.
What Thermal Runaway Means
Thermal runaway is an uncontrolled self-heating reaction inside a battery cell.
In normal use, a lithium-ion battery stores and releases energy in a controlled way. When something goes wrong inside the cell, heat can begin to build faster than the battery can manage. That heat can trigger more internal reactions, which create still more heat.
Once that process becomes self-sustaining, the battery may vent gas, release smoke, ignite, rupture, or cause nearby cells to fail.
In plain language: thermal runaway is the point where the battery is no longer just getting hot. It is driving its own failure.
This is one reason lithium-ion battery fires can feel sudden. The battery may be in trouble internally before there is a visible sign that a person nearby can recognize.
Why Off-Gassing Matters
Before visible flame appears, a failing lithium-ion battery may release gas. This is often called off-gassing or venting.
That gas can be flammable, toxic, hot, and difficult to identify at first. It may appear as white-gray smoke, vapor, haze, or a sudden release from the battery area. It may also come with odor, hissing, popping, swelling, or unusual heat.
Off-gassing matters because it can be both a warning sign and a hazard.
FSRI research on residential energy storage fire dynamics has shown that lithium-ion battery thermal runaway can generate flammable off-gas. FSRI also notes that thermal runaway in lithium-ion batteries effectively always produces a flammable mixture of gas and vapor, with several possible ignition sources.
That is why enclosed spaces matter. A garage, utility room, apartment, charging room, cabinet, or storage area can allow gases to accumulate before ignition.
Why Earlier Warning Matters
Smoke alarms and heat detection are essential parts of fire safety. They should be used and maintained wherever required.
But lithium-ion battery failure can begin before smoke or room-level heat is obvious. In some situations, by the time a person sees smoke, the failure may already be moving quickly.
Earlier warning matters because it can give people more options.
An earlier alert may support evacuation, shutdown, disconnect, isolation, emergency notification, or a safer response plan before a battery problem becomes a visible fire emergency.
Early warning does not eliminate risk. It does not replace smoke alarms, certified products, safe charging habits, professional installation, or emergency response.
It adds another layer closer to the beginning of the failure.
Common Warning Signs
Stop using or charging a lithium-ion battery if you notice:
- Unusual heat
- Swelling or bulging
- Hissing, popping, or crackling sounds
- Smoke, vapor, or haze
- A strange or chemical odor
- Leaking
- Discoloration
- Sparking
- A change in shape
- A charger or device behaving differently than normal
The U.S. Fire Administration advises people to stop using lithium-ion batteries if they notice odor, color change, too much heat, shape change, leaking, or odd noises.
If there is smoke, fire, active venting, strong odor, or signs of battery failure, move away from the area and call emergency services. Do not try to carry a failing lithium-ion battery through a home, business, or occupied space.
Safer Charging Practices
Safer charging starts with consistency.
Use the charger supplied or approved by the manufacturer. Avoid cheap replacement chargers, counterfeit batteries, damaged packs, and batteries that have been rebuilt or modified by unqualified people.
Charge on a hard, open surface away from beds, couches, paper, clothing, cardboard, gasoline, solvents, and other combustible materials.
Do not charge near exits, stairways, doors, or paths people may need to use during an emergency.
Avoid charging unattended or overnight when possible. If a battery begins to fail while people are asleep or away, the response window may be much shorter.
Unplug the charger when charging is complete, unless the manufacturer gives different instructions.
Store spare batteries away from anything that can burn. The U.S. Fire Administration advises storing spare lithium-ion batteries away from combustible materials and avoiding direct sunlight or hot cars.
Do not place lithium-ion batteries in household trash. Use an approved battery recycling or disposal location. USFA advises recycling lithium-ion batteries properly instead of throwing them away.
Home Energy Storage Safety Notes
Home energy storage systems and solar battery banks are becoming more common in residential energy planning. These systems can provide backup power, improve solar use, and support greater energy resilience.
They also require thoughtful safety planning.
A home battery should be installed by qualified professionals in accordance with manufacturer instructions, electrical code, fire code, local permitting requirements, and applicable standards.
Battery systems should be installed in clean, accessible locations. They should not block exits. They should not be surrounded by household clutter, flammable materials, gasoline, solvents, or other storage that could make an incident worse.
Homeowners should know where the system is located, how to shut it down if instructed, who installed it, who services it, and what warning notifications mean.
Local first responders should be able to identify that a home has solar and/or battery storage. Clear labeling, documentation, and accessible equipment can matter during an emergency.
If a home energy storage battery is smoking, burning, venting, making unusual sounds, producing odor, or showing signs of failure, evacuate and call emergency services.
Micromobility Charging Safety Notes
E-bikes, scooters, hoverboards, e-skateboards, and other micromobility devices are useful and increasingly common. They are also often charged in homes, apartments, garages, shops, and shared spaces.
That makes charging behavior important.
Use only the correct charger for the battery and device. A plug that fits does not mean a charger is safe or compatible.
Do not charge micromobility batteries near doors, hallways, stairways, bedroom exits, or fire escapes.
Do not charge damaged batteries. A battery that has been dropped, crashed, crushed, exposed to water, repaired poorly, or modified should be treated carefully.
Avoid charging multiple batteries in a crowded or cluttered area. Shared charging environments should have clear rules, approved chargers, open space, and a response plan.
CPSC’s 2025 micromobility battery rulemaking package identified thermal runaway as the primary risk associated with lithium-ion batteries used in micromobility products, with hazards including fires, explosions, gas releases, burns, overheating, and smoke inhalation.
How Flashpoint Fits Into Battery Safety
Flashpoint Safety Systems develops early-warning lithium-ion battery safety technology for battery charging and storage environments.
The goal is not to make people afraid of lithium-ion batteries. The goal is to help people use them with a better safety layer.
Flashpoint products are designed to support earlier warning and faster response when a battery environment begins to show signs of failure. They are intended to work alongside safe charging practices, certified equipment, professional installation where required, applicable codes, working smoke alarms, and emergency planning.
No safety product can eliminate all risk. But in a lithium-ion battery failure, the timing of the first warning can matter.
Product Safety Position
Flashpoint products are designed to support earlier warning and safer response to lithium-ion battery failure conditions. No safety product can eliminate all risk.
Users should always follow manufacturer instructions, use certified equipment where available, comply with applicable codes and standards, maintain working smoke alarms, and evacuate immediately if there is smoke, fire, unusual odor, heat, swelling, popping, hissing, leaking, or other signs of battery failure.
Sources and References
Fire Safety Research Institute: Lithium-Ion Battery Fire and Explosion Hazards
FSRI’s guide explains lithium-ion battery construction, thermal runaway, and potential fire and explosion hazards.
Fire Safety Research Institute: Residential Garage Explosion Hazards from Lithium-Ion Battery Thermal Runaway
FSRI research describes flammable off-gas hazards from lithium-ion battery thermal runaway, including residential garage scenarios and energy storage system context.
U.S. Consumer Product Safety Commission: Proposed Safety Standard for Lithium-Ion Batteries Used in Micromobility Products
CPSC’s 2025 proposed rule package addresses micromobility lithium-ion battery hazards, including fires, explosions, gas release, burns, overheating, and smoke inhalation.
Fire Department of the City of New York: Lithium-Ion Battery Fire Data
FDNY reported 277 lithium-ion battery fires in 2024 and described ongoing fire-prevention, inspection, and education efforts.
U.S. Fire Administration: Battery Fire Safety
USFA provides public-facing safety guidance for using, storing, charging, and disposing of lithium-ion batteries.
Federal Aviation Administration: PackSafe Lithium Battery Guidance
FAA guidance explains that lithium-ion batteries can overheat and enter thermal runaway under several conditions, including damage, overheating, water exposure, overcharging, improper packing, or manufacturing defects.
Media Contact
For questions, interviews, product information, images, or additional background, contact:
West Carnahan
Flashpoint Safety Systems
Email: west@flashpointsafety.com
Phone: 614-286-2484
Website: flashpointsafety.com
