What thermal runaway is
Thermal runaway is self-accelerating heating caused by internal reactions that may spread between battery cells. It combines stored energy with materials capable of generating flammable gases and hazardous products. It can cause fire or explosion, although its development depends on battery chemistry, state of charge, design and condition.
Related concept: Fire risk.
What can initiate it
Triggers include internal defects, mechanical damage, unsuitable temperatures and incorrect charging. A crushed or impacted battery needs assessment even if it still powers the equipment. Compatible chargers and battery-management systems form part of prevention. Altering protections or reusing damaged modules can introduce conditions not anticipated in the design.
Warning signs and exposure
Abnormal heating, deformation, gas or smoke emission and other changes may warn of failure. A person must not bring their face close or handle the battery to check its condition. Gases and fumes may be flammable and toxic; concern cannot be limited to flames. The protocol must establish alerting, separation of people and action by competent personnel.
Preparing charging and storage
Location, ventilation, nearby combustibles, vehicle damage and escape routes are assessed. Defective batteries require a specific removal and management procedure, without improvised containers or quarantine locations. Detection and protection must match the chemistry, size and configuration of the installation. A solution for a small device cannot be extrapolated to a large system.
Example of impacted equipment
A hypothetical pallet truck receives an impact that deforms its battery enclosure. Continuing to charge without review adds uncertainty about the damage. The procedure must remove the equipment from use, raise the alert and organise assessment according to the manufacturer, without exposing someone to manually moving a battery already showing signs of failure.
Limits of initial intervention
There is no universal extinguishing recipe: the strategy requires planning with specialists and emergency services. Flame cessation does not demonstrate that the reaction has ended or exclude reignition. The cited maritime guidance provides technical criteria specific to that sector and is not a general standard for every land-based workplace.
