Why do electric vehicle batteries catch fire?, Pg12

Key Highlights:

• A house fire in Indore on March 18 killed eight people; an electric vehicle (EV) charging point is suspected to be the cause.
• Lithium-ion batteries, used in most EVs, can experience thermal runaway, a chain reaction of overheating cells that releases flammable gases.
• Factors like impact damage, overcharging, manufacturing defects, external heat, aging, and flooding can trigger thermal runaway in EV batteries.
• Updated safety norms for EV batteries were released by the Bureau of Indian Standards (BIS) in 2023 under the AIS-156 standard.

Detailed Insights:

• Thermal runaway occurs when a single battery cell overheats, causing adjacent cells to do the same, overwhelming the cooling system and potentially leading to fire.
• EV battery packs are typically protected by reinforced steel or aluminum shells, but impacts can damage the casing and cause short circuits.
• Charging systems in EVs have safeguards to prevent overcharging, but using third-party or damaged chargers can bypass these limits and increase risk.
• Manufacturing defects, such as metal protrusions, can cause internal short circuits as the battery expands and contracts during use.
• External conditions like hot weather and direct sunlight can add to thermal stress, while flooding can cause short circuits due to contaminated water infiltrating the battery pack.
• New cooling methods are being developed, such as using coolants that evaporate to improve heat transfer, and manufacturers are exploring solid-state batteries to reduce thermal runaway risk.
• Users can take precautions by using certified chargers, avoiding unattended charging, ensuring proper home electrical systems, and having batteries inspected after impacts.
• The AIS-156 standard requires tests to check heat propagation in batteries and mandates that battery packs provide users with at least five minutes to escape before a fire.

Key Concepts Involved:

• Thermal Runaway: A chain reaction in lithium-ion batteries where overheating in one cell causes adjacent cells to overheat, potentially leading to fire.
• Lithium-ion Battery: A type of rechargeable battery commonly used in electric vehicles, known for its high energy density and relatively long lifespan.
• Battery Management System: An onboard computer that monitors and regulates the temperature of an EV's battery to keep it within a safe range.