Staying Safe with Lithium‑Ion Batteries in Our Homes
Written by Corey Kinsman, P.E. on September 23, 2025
In partnership with Summit Fire Consulting.
Lithium‑ion (Li‑ion) batteries have changed the way we live. They power our phones, laptops, power tools, wheelchairs, toys, and the e‑bikes and scooters that are becoming more common in cities. These rechargeable batteries pack a lot of energy into a small space. They are safe when used correctly, but because they store so much energy, they can overheat, catch fire, or even explode when things go wrong. This article explains why Li‑ion batteries can be dangerous, what factors increase the risk, and how to protect yourself and your loved ones.
Why lithium‑ion batteries can catch fire
High energy density and flammable materials
Li‑ion batteries store a lot of energy in a small package, and many batteries consist of multiple individual battery cells. When this energy is released in an uncontrolled way, it produces heat that can turn internal components into flammable and toxic gases. The materials in these batteries are combustible. When the battery goes into thermal runaway (a self‑heating chain reaction), cells can overheat, burn, or explode. Laboratory tests have shown that temperatures during thermal runaway rise extremely quickly, and flames can extend several feet above an e‑scooter battery.
Causes and Severity
Most Li-ion battery fires start in a single cell when the battery is stressed or damaged. Dropping a tool, crashing an e-bike or scooter, or crushing a pack can break the thin barrier between internal components, creating a short circuit that generates intense heat. Using the wrong charger or leaving a device plugged in too long can also cause electrical failure. Heat itself is another common trigger. For example, charging in a hot car, leaving a device in direct sunlight, or covering a battery and preventing it from cooling can all speed up chemical reactions that can spiral out of control.
Poor-quality or counterfeit batteries are especially risky. Defects or contaminants introduced during manufacturing can cause internal shorts or make the battery cells more vulnerable to other damage.
Fire severity depends on several factors. A fully charged battery holds more energy, so it can release more heat and gas if it fails. Using poor quality or mismatched chargers can overcharge a battery and push it past its limits. Charging in tight spaces (ex. on a couch, under a pillow, or near flammable items) gives heat and gases nowhere to go, potentially causing damage to the battery and increasing the potential fire size. Any battery that has been dropped, crushed, gotten wet, or shows signs of swelling, leaks or corrosion should never be charged again.
Safe buying, charging, and storage practices
Following simple precautions can greatly reduce the likelihood of a battery fire:
Buy quality products – Only purchase devices and replacement batteries listed or certified by a recognized testing laboratory.
Use the correct charger – Only use the charging equipment supplied with your device.
Do not overcharge or fully discharge – Disconnect the charger once the battery is full, and avoid leaving devices plugged in overnight.
Charge and store in a safe place – Keep charging devices away from anything that can burn.
Monitor while charging – Avoid charging when you are asleep or away from home. Li‑ion batteries can go from smoke to flames within seconds, so early detection is critical.
Handle with care – Do not drop, crush, or puncture batteries.
Recycle properly – Do not throw Li‑ion batteries in the trash. Take used or damaged batteries to a local recycling location or hazardous waste facility.
Everyday battery safety
Li-ion batteries are all around us, powering phones, laptops, smart watches, e-bikes, tools, and more. The good news is that most are safe when handled correctly. Following the practices discussed above, such as using certified products, charging in safe locations, and storing at room temperature, greatly reduces the risk of fire. And if something does go wrong, acting quickly makes a big difference in limiting harm and damage.
Remember, if a battery smells bad, gets very hot, makes strange noises, or looks swollen, stop using it immediately and call for help. For additional resources, visit the NFPA’s lithium‑ion battery safety page and the US Fire Administration’s CHARGE safety messages.
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