Battery-powered vehicles are becoming more common across transportation, material handling, construction, ports, mining, and other demanding industries. From electric buses and airport ground support equipment to forklifts, compact construction equipment, utility vehicles, and smaller mobile machines, more operations are asking:
How do you protect operators and equipment from lithium-ion battery fires?
The answer is not as simple as choosing a standard fire suppression system and applying it to a battery-powered machine. Lithium-ion battery fires behave differently than traditional diesel equipment fires. They can involve thermal runaway, intense heat, off-gassing, reignition risk, and limited access to the source of the fire.
That is why battery fire protection requires a different strategy - one built around the specific vehicle, battery location, operating environment, and available safety systems.
At AFEX, that strategy starts with a Fire Risk Assessment and focuses on early detection, rapid system actuation, liquid agent cooling, and helping provide time for the operator to safely exit the machine.
Lithium-ion batteries store a large amount of energy in a compact space. When a battery cell is damaged, overheated, overcharged, or otherwise compromised, it can enter a condition known as thermal runaway.
Thermal runaway is an uncontrolled increase in temperature and pressure inside the battery cell. Once it begins, heat can spread from one cell to surrounding cells, increasing the risk of fire growth, reignition, and hazardous conditions around the machine. The National Transportation Safety Board has noted that damaged lithium-ion battery cells can experience thermal runaway and create reignition/fire risks, while UL’s Fire Safety Research Institute identifies physical damage, overheating, and battery management system failure as common causes.
For heavy equipment, this creates a very specific challenge. The battery may be difficult to access. It may be enclosed in a sealed pack. It may be located near hydraulic components, electrical systems, or other fire hazards. And by the time visible flames appear, the operator may already be in a dangerous situation.
That is why battery fire protection has to focus on early warning and operator egress, not just fire knockdown.
Lithium-ion batteries introduce fire risks that are different from those found on traditional diesel-powered machines. Battery size, chemistry, enclosure design, location on the vehicle, and accessibility all affect how a fire protection system should be designed.
That is why AFEX recommends completing a Fire Risk Assessment for each battery-powered vehicle. A properly designed system considers the battery location, surrounding hazards, available detection methods, operator egress path, and whether the fire suppression system can interface with the OEM’s Battery Management System.
The goal is to apply the right protection strategy for the machine. In many applications, that means:
AFEX recommends a layered approach to battery fire protection for heavy equipment.
Most battery-powered vehicles include a Battery Management System, or BMS. The BMS monitors battery health, including temperature, voltage, and other conditions that may indicate a developing problem.
Ideally, the OEM’s BMS alerts the operator, initiates machine shutdown, and sends a signal to the AFEX Control Unit so the fire suppression system can actuate while the operator exits the machine.
For battery-powered heavy equipment, early detection is one of the most important parts of operator protection.
The BMS is important, but it should not be the only layer of protection.
If the BMS cannot be connected to the fire suppression system, or if it does not detect a fault, traditional detection can provide an additional layer of safety. AFEX systems can use detection methods such as linear wire detection or spot heat sensors to identify heat from a developing fire event.
Traditional detection is also important because not every fire starts inside the battery. Battery-powered heavy equipment can still face fire risks from:
A lithium-ion battery is a high-risk fuel source. Suppressing an external fire before it reaches the battery can help protect the operator and reduce the chance of a more serious thermal event.
For battery fire protection, AFEX recommends liquid agent systems because cooling is critical.
During thermal runaway, heat from damaged cells can spread to surrounding cells. A liquid agent can help lower temperatures around the battery modules and slow the progression of the event.
This cooling effect matters because time matters.
A fire suppression system on battery-powered equipment should be designed to provide enough discharge time to support safe operator egress. AFEX liquid agent systems can be configured for longer discharge durations, including on large machines where the operator may need more time to exit safely.
By focusing on cooling, discharge duration, and system design, AFEX helps support a safer response when a battery fire event occurs, giving operators valuable time to shut down and exit the machine.
AFEX does offer an off-gassing sensor option when BMS signals are unavailable and the application conditions support effective gas detection.
Off-gassing sensors can detect gases released from damaged battery cells or modules before a more visible fire event develops. However, they are not always the best or most practical detection method for heavy equipment.
AFEX has found that, in many cases, tying into the OEM’s BMS is more effective than relying on off-gassing detection. Off-gassing sensors require specific conditions to work properly. The sensor generally needs access to the area where off-gassing would originate, such as inside the battery pack or module, and the pack or module must be sealed from the external environment.
If those conditions cannot be met, off-gassing detection may not be recommended.
When evaluating fire suppression for battery-powered heavy equipment, operations teams should look for a system that is designed around the machine, the operator, and the real-world fire risks of the application.
Important questions include:
Can the fire suppression system connect to the OEM’s Battery Management System?
A BMS signal can help actuate the system early, before the situation escalates.
Is there a backup detection method?
Linear wire or spot heat detection can add protection if the BMS does not detect a fault or if an external fire develops.
Does the system provide cooling?
Cooling is critical for slowing heat propagation during a lithium-ion battery fire event.
Is the system designed to give the operator time to exit?
Operator egress should be a central design goal.
Has a Fire Risk Assessment been completed?
Battery location, pack design, machine size, access points, and surrounding hazards all affect the fire suppression system design.
Does the system protect more than just the battery?
Battery-powered machines can still have hydraulic, electrical, and external fire risks that need to be considered.
Battery fire protection for heavy equipment requires a practical, application-specific approach.
Lithium-ion battery fire events can develop quickly and behave differently than traditional equipment fires. That is why early detection, effective system actuation, cooling, and operator egress should all be considered when designing protection for battery-powered machines.
The right system can help detect abnormal conditions earlier, apply agent quickly, cool the affected area, and suppress surrounding hazards before the event escalates. Most importantly, it can help provide valuable time for the operator to safely shut down and exit the machine.
That is the purpose of AFEX fire suppression systems for battery-powered heavy equipment: to support a safer response when every second counts.