Health and Safety

July 15, 2026 Published by Golden Horseshoe Chapter - By Allen Kim

Lithium-Ion Batteries – Building Fire Risks

From the Volume 28, Summer 2026 issue of the CCI GHC Condo News Magazine

Imagine you are in an elevator when an E-bike battery suddenly starts hissing noxious gas that then erupts in flames. This scenario is something that happened recently on a Toronto TTC subway car. According to Global News and Toronto Fire, the lithium-ion battery from the E-bike was the source of the fire.

If not for the subway reaching the platform near the start of the fire, this could have been a much more catastrophic event.

What’s the Issue?

Lithium-Ion batteries are known to be potential fire hazards, and the reasons may not be what you think.

Lithium-Ion (Li-Ion) batteries are common throughout modern life and can be present in rechargeable electronic devices such as;

• Power tools
• Portable chargers, Toys
• Electronics (computers, phones, tablets, smartwatches)
• Vaping (e-cigarettes)
• E-scooters, E-bikes and mobility devices

E-bike fire on Toronto subway car¹

Examples of pouch, cylindrical, and prismatic Lithium-ion batteries

Due to the make-up and chemistry of Li-Ion batteries, energy is stored within the battery cell and if damaged or overheated can result in failure without prior notice. A battery failure can include gas diffusion, fire, or explosion.

In the case of Li-Ion batteries, no additional ignition source is needed, both the combustion source and ignition is already inside the battery itself.

Examples of pouch, cylindrical, and prismatic Lithium-ion batteries.²

That being said, risks related to battery failures are reported to be very low. According to Health Canada, between 2013 and 2023, Health Canada’s Consumer Product Safety Program received 924 reports of lithium-ion battery incidents compared to an unreported total number of batteries, which is likely within the 10’s of millions. So the overall risk is very low. However there seems to growing consensus in the Industry that issues with mobility devices and non-certified products may be the primary source of the issues.

How are Batteries made?

Battery components are made of very thin layers of graphite and a metal oxide, separated by a very thin layer of plastic known as a ‘Separator’. An electrolyte is poured into this ‘sandwich’ or ‘roll’ (i.e., lithium salts) and the lithium ions are forced through the separator between the cathode and anode, providing power.

Lithium-ion cell battery example³

A typical cylindrical battery includes hundreds of layers wrapped into a palm-sized battery.

In mobile devices, such as E-scooters or E-bikes, many cylindrical batteries are installed together, which provides significant energy. These types of devices can also be exposed to impacts from curbs or bumps on the road/sidewalk, vibrations, and the elements under normal operation. These conditions increase opportunity for damage to the batteries over the long term.

If the separator sheet becomes damaged, or if the battery does not function properly, degrades over time, or is overheated during charging, then an uncontrolled chemical chain reaction can occur where the stored energy continues to build up and up without stopping. This reaction is self-sustaining and generally cannot be put out with regular firefighting methods (e.g., water).

E-bike batteries after involvement in a fire

Single battery after involvement in a fire.

This condition is called ‘Thermal Runaway’. As the name implies, it is like a runaway train that cannot be stopped.

Thermal Runaway

When Thermal Runaway occurs, it is a self-sustaining chemical reaction. The effects of one battery cell entering Thermal Runaway can easily trigger nearby battery cells to enter a similar condition. Essentially, there is a cascading effect that can occur with one battery triggering nearby cells to catch fire or explode, resulting in an increasingly dangerous situation. Trying to put out these types of fires is complicated and best left to the professional fire service. Water does not put out battery fires, but is generally used to cool down adjacent batteries, giving enough time to allow the battery to extinguish on its own.

Site Specific Issues Related To Condominium Buildings

Multi-unit condominiums introduce additional layers of fire safety issues that should be reviewed periodically by Building Management. The availability and price point of mobility devices such as e-scooters and e-bikes have allowed these devices to become pervasive in our communities.

Example of E-scooter battery fire AI Generated image - Chatgpt.com

The entrances and exits to buildings, as well as elevators, are bottlenecks where mobility devices are likely to be encountered daily. The travel path to and from a building, as well as storage locations and underground parking, should be carefully considered when allowing larger Li-Ion batteries into the building.

Storing large quantities of E-bikes or E-scooters in common storage rooms brings additional levels of fire risk. If one device enters a Thermal Runaway condition, it may trigger nearby devices, resulting in a much larger and potentially uncontrollable situation. The number of stored mobility devices should be reduced as much as possible. Maximizing the distance between adjacent devices will also help minimize cascading effects.

Storage areas should be adequately ventilated and located far from combustible materials or critical building services. Consideration for outside storage facilities may be a desired approach.

The charging location for these large battery packs also needs to be carefully considered so that in an emergency, people can evacuate to the exit corridors and outside. The egress doorway and the travel path to the exit should always be unobstructed, even in the event of a battery failure, fire, or off-gassing from a battery pack.

Essentially, battery packs should not be charged at or near exit doors or hallways in the path to the exit. It goes without saying that battery packs should also not be charged in public spaces or hallways.

The environmental and health effects of Li-Ion battery fires are also a concern. The ‘smoke’ produced during these events includes various chemicals from the battery chemistry, which can be more hazardous to health than smoke from a typical wood-burning or combustible material fire.

Resident education and battery safety information will be important approaches to reducing building incidents.

Best Practices

Building Management, Operators, and Boards of Directors may want to consider implementing recommendations from regional Authorities such as the City of Toronto, Fire Services, or Health Canada, which can include, but not limited:

• Only purchase CSA, cUL, or cETL certified batteries.
• Properly charge and use batteries as per the Manufacturer recommendations.
• Use only the battery that is designed for the device and the charger cable/cord that came with it. If a replacement charger is needed, buy it from a trusted source and make sure the voltage and current are compatible with the device.
• Never modify or tamper with the battery.
• Do not keep batteries plugged in while not in use.
• Never modify or tamper with your battery.
• Keep batteries away from living spaces, and egress routes.

Sample Certification marks

The overall failure rate of Lithium-ion batteries is low considering the number of batteries in circulation. However, the popularity of mobility devices like E-bikes, E-scooters and similar devices, where the larger batteries are at a higher risk of damage from use, needs to be considered as part of any building’s fire safety plan. Knowing the risks and recommended safety practices will hopefully reduce and minimize the extent of damage or disruption which could occur if (or when) a battery fails.

---

Allen Kim, P.Eng is a structural engineer and certified fire and explosion investigator with over 17 years of varied practical engineering experience. His expertise includes forensic and building assessments, the preparation of restoration scope of work, Code evaluation and cause & origin investigations.
Brown & Beattie Ltd.

---

¹Global News - “Significant and aggressive’ e-bike fire on TTC subway car sparks safety concerns - January 2, 20024
²Image created using AI, ChatGPT
³www.batterycouncil.org/battery-facts-and-applications/about-lithium-ion-batteries/