Electric Vehicle Thermal Runaway Explained

Thermal runaway is the most dangerous phenomenon in electric vehicles—a self-sustaining chain reaction that can turn a minor incident into a 5,000°F inferno. Understanding this process is critical for product liability claims against EV manufacturers.

What Is Thermal Runaway?

Per NTSB research, thermal runaway occurs when lithium-ion battery cells overheat beyond their stable operating temperature. This triggers an exothermic (heat-releasing) reaction that raises temperature further, causing adjacent cells to fail in cascade.

The Cascade Effect

• 1. Initial cell damage from crash, defect, or overcharging
• 1. Cell temperature rises past safe threshold (~130°C)
• 1. Electrolyte breakdown releases gases
• 1. Heat spreads to adjacent cells
• 1. Adjacent cells enter runaway
• 1. Temperature reaches 1,000-1,800°C (1,800-3,200°F)
• 1. Battery pack becomes impossible to extinguish

Firefighting Challenges

NFPA guidelines document extreme difficulties: 3,000-8,000 gallons of water needed (vs. 300 for gasoline fires), 24-hour monitoring required for rekindle, toxic fume hazards for responders, and special training required for EV fires.

Triggers for Thermal Runaway

• Crash damage: Impact punctures cell separators
• Manufacturing defects: Contamination in cell production
• Overcharging: BMS failure allows overcharge
• External heat: Nearby fires or high ambient temperatures
• Age/degradation: Worn cells more susceptible

Major Recalls for Fire Risk

Manufacturers have recalled millions of vehicles for thermal runaway risk: GM Bolt (143,000 vehicles), Hyundai Kona EV (82,000), Ford Mustang Mach-E (49,000), and multiple Tesla campaigns.

Legal Implications

Thermal runaway incidents support: design defect claims (inadequate thermal management), manufacturing defect claims (cell contamination), failure to warn claims (insufficient fire risk disclosure), and negligence claims (known risks not addressed).