Thermal Runaway Response When Seconds Matter

A lithium-ion battery incident rarely begins with visible flame. In many cases, cells first release hydrogen, electrolyte vapours and volatile organic compounds as internal damage develops. An effective thermal runaway response is therefore not simply a fire response plan. It is a staged operational process that turns those early indicators into decisive action while there is still time to protect people, isolate equipment and preserve critical infrastructure.

For BESS operators, data centre managers, EV charging providers and industrial facility leaders, the objective is clear: detect the developing fault before smoke, fire or violent cell failure removes safe options.

Why thermal runaway response must start before smoke

Thermal runaway is a self-heating failure within a battery cell. It can result from internal short circuits, manufacturing defects, overcharging, external heat, mechanical damage, water ingress or failures in battery management and cooling systems. As heat builds, cell materials break down and release flammable and toxic gases. Adjacent cells can then be affected, allowing the event to propagate through a module, rack or container.

Once flames are visible, the response is primarily about life safety, emergency services coordination and limiting escalation. That response remains essential, but it is late in the failure sequence. Smoke detection, thermal imaging and fire suppression systems each have a place, yet they may not identify the earliest stages of cell degradation.

Off-gas detection provides a different layer of protection. Monitoring hydrogen, VOCs, electrolyte vapours, humidity and temperature trends can identify abnormal battery behaviour before smoke develops. This gives operators an opportunity to initiate a controlled response rather than reacting to a fully developed emergency.

Build the thermal runaway response around clear alarm stages

A response plan is only useful if the people and systems receiving the alarm know what it means and what must happen next. Generic alerts such as “battery fault” invite delay and inconsistent judgement. A better approach uses defined alarm levels, each tied to verified actions, nominated decision-makers and documented escalation paths.

Stage 1: Investigate an early-warning condition

An initial off-gas or environmental alarm should trigger a prompt investigation by authorised personnel or a monitored control room. The goal is to determine whether the reading is isolated, sustained, increasing or supported by other evidence such as elevated temperature, battery management system faults, cooling alarms or abnormal charging behaviour.

At this stage, personnel should not open battery enclosures, racks or cabinets merely to inspect the source. Opening an enclosure may expose workers to hazardous gases, introduce oxygen or alter the conditions around a compromised battery. The site procedure should instead rely on remote information first: detector readings, BMS data, CCTV where fitted, ventilation status and equipment operating history.

For a BESS, this may mean placing the affected string, rack or container under heightened observation while a competent technician assesses the system remotely. In a commercial EV charging area, it may involve stopping charging to the affected bay and keeping people clear until the battery owner, emergency services or qualified responders provide direction.

Stage 2: Make the asset safe where it is safe to do so

If readings persist or rise, the response should move from investigation to controlled risk reduction. Depending on the system design and site operating procedures, this may include stopping charge and discharge, electrically isolating the affected battery section, placing the BESS into a safe state, inhibiting automatic restart and shutting down nearby equipment that could increase ignition risk.

These actions must be engineered and approved in advance. Isolation should not be improvised during an incident, and it must never put personnel in close proximity to a potentially failing battery. Battery systems can retain significant stored energy after external supply isolation, so electrical isolation does not automatically mean the hazard has ended.

Ventilation is similarly site-specific. Controlled ventilation can reduce the concentration of flammable gases in some installations, but the strategy must align with the enclosure design, fire engineering approach and equipment manufacturer requirements. Poorly considered ventilation actions can spread contaminated air or introduce ignition risks elsewhere.

Stage 3: Escalate before conditions become untenable

A confirmed or escalating off-gas event requires a higher level of control. Establish exclusion zones, restrict access, notify the site emergency response team and contact emergency services where the risk assessment or alarm threshold requires it. In Australia, call Triple Zero (000) when there is immediate danger, smoke, fire, injury, a suspected uncontrolled battery event or uncertainty about whether conditions can be safely managed.

Emergency responders need useful information on arrival. The incident controller should be ready to provide battery chemistry, system capacity, layout drawings, access points, isolation locations, live detector trends, BMS alarms, current operating state and details of any fire suppression or ventilation systems. A concise site-specific emergency information pack can save valuable time.

Do not rely on a handheld extinguisher as the primary answer to a propagating lithium-ion battery event. Extinguishers may address small secondary fires in surrounding materials, but a battery in thermal runaway can reignite or continue generating heat and gases. Fire service tactics, cooling requirements and monitoring periods will depend on the battery type, installation and scale of the event.

Integrate detection with the systems operators already use

Early warning only improves safety if the signal reaches the right people and initiates the right controls. For industrial sites, detection should be connected to the operational environment rather than treated as a standalone device with a local audible alarm.

Relay outputs can trigger local alarms, shutdown sequences or ventilation controls where the site engineering design permits. Modbus RTU compatibility can bring live gas and environmental data into SCADA, BMS or building management platforms, allowing control room staff to view trends alongside electrical performance and fault status.

This integration matters because a single gas reading is not the whole picture. A rising hydrogen concentration combined with battery temperature deviation, cooling failure and an active BMS alarm presents a stronger case for escalation than any one signal alone. Conversely, the response plan should address nuisance alarms and sensor faults so teams do not become desensitised to alerts.

Evikon E2673 off-gassing detection systems are designed for this operational role in BESS and critical infrastructure environments. Their value is not simply detecting a gas. It is providing early, actionable evidence that can be integrated into a site’s wider protection and continuity strategy.

Design the response plan for the specific installation

There is no universal thermal runaway response that suits every lithium-ion application. A utility-scale containerised BESS, UPS room, battery manufacturing line and EV charging hub have different hazards, access arrangements, occupancy levels and control systems.

For example, a remotely operated solar farm may prioritise SCADA alarm routing, automatic safe-state logic and clear emergency access information for responders travelling to site. A data centre may place greater emphasis on preventing unplanned shutdowns while protecting occupied technical spaces and maintaining service continuity. A workshop charging multiple e-bikes and power tools requires simple, visible instructions: stop charging, keep people away, do not move a hot or damaged battery, and call 000 if smoke, fire or immediate danger is present.

The response plan should identify who has authority to stop operations, who contacts emergency services, who communicates with asset owners and insurers, and who can authorise re-entry. It should also account for after-hours alarms. A detector is of limited value at 2 am if notifications lead only to an unattended inbox.

Test the plan without waiting for an incident

A documented procedure that has never been exercised is not a dependable emergency control. Regular drills should test alarm receipt, remote verification, shutdown authority, contractor responsibilities, emergency service notifications and access to site information. These exercises often reveal practical gaps, such as incorrect contact details, unclear key access, unavailable drawings or conflicting shutdown instructions.

Maintenance should be equally deliberate. Detection equipment requires correct placement, commissioning, periodic functional checks and calibration or replacement in accordance with the manufacturer’s requirements. Sensor location is especially important because gas movement is affected by enclosure geometry, ventilation paths, obstructions and the gases being monitored.

After any alarm, whether genuine or false, review the event. Determine what was detected, how quickly people responded, whether automated actions performed as intended and whether thresholds or procedures need adjustment. This is how an early-warning system becomes an improving safety process rather than a compliance item.

The strongest protection is created well before an emergency: early detection, clear authority, engineered controls and a team that knows exactly what to do when the first warning arrives.