Why in news?

A devastating fire tore through a house in Indore recently, killing 8 people — including 2 children. The blaze is suspected to have originated from an EV charging point located outside the house. An official investigation is currently underway.

What’s in Today’s Article?

• Safety of EV Batteries
• Causes of Thermal Runaway in EV Batteries
• Impact of External Conditions on EV Battery Safety
• Industry and User Measures to Improve EV Battery Safety

Safety of EV Batteries

• Lithium-Ion Batteries: Common but Efficient - Most EVs use lithium-ion batteries, similar to those in smartphones and laptops. They offer high energy density and are generally safe when properly managed.
• Role of Battery Management System (BMS) - EVs are equipped with a Battery Management System (BMS). It regulates temperature and ensures the battery operates within safe limits during charging and discharging.
• Risk of Thermal Runaway - A key risk is thermal runaway, where:
  • One battery cell overheats
  • Heat spreads to nearby cells
  • A chain reaction occurs, overwhelming the cooling system.
• Fire and Toxic Gas Risk - During thermal runaway, batteries release flammable and toxic gases such as hydrogen fluoride. These gases can intensify fire risk and make incidents more hazardous.
• Overall Insight - EV batteries are generally safe, but rare failures like thermal runaway can lead to serious fire hazards if not properly controlled.

Causes of Thermal Runaway in EV Batteries

• Physical Damage to Battery Pack - Strong impacts (especially to the undercarriage) can damage the battery casing. This may puncture or deform cells, leading to internal short circuits and overheating.
• Overcharging and Faulty Chargers - Charging beyond safe limits can cause charge buildup in unstable areas of the battery. Use of third-party or damaged chargers increases this risk. Repeated overnight charging with unsafe chargers can worsen the problem.
• Manufacturing Defects - Rare defects like metal protrusions inside cells can connect positive and negative electrodes. This leads to sudden high current flow, generating excessive heat and triggering thermal runaway.
• Electrical Infrastructure Issues - Weak or old wiring and extension cords may not handle sustained current. This can cause overheating during charging, indirectly increasing fire risk.

Impact of External Conditions on EV Battery Safety

• Heat and Thermal Stress - High temperatures, especially during Indian summers, can strain the cooling system. Parking in direct sunlight or charging immediately after long drives increases thermal stress on batteries.
• Battery Age and Maintenance - Over time, batteries degrade internally, increasing risk. Ignoring warning signs or skipping inspections may hide issues like swelling or chemical breakdown.
• Risk from Flooding - Floodwater can enter battery packs, causing short circuits. Several EV fires have been reported days after vehicles were submerged.
• EV vs Petrol Vehicle Fires - EVs are not uniquely dangerous—petrol vehicles catch fire more often. However, EV battery fires:
  • Burn hotter and faster
  • Are harder to extinguish due to oxygen release
  • Firefighting requires large amounts of water or special equipment.
• Role of Surrounding Factors - Fire risks can increase due to external elements like: LPG cylinders stored nearby; Presence of other vehicles; Power failure affecting safety systems (e.g., electronic locks).

Industry and User Measures to Improve EV Battery Safety

• Advanced Cooling Technologies - EVs use coolant channels to absorb and dissipate heat. New systems are being developed where coolant evaporates to improve heat transfer, helping manage sudden temperature spikes.
• Safer Battery Design Innovations - Shift towards solid-state batteries (using solid electrolytes) to reduce fire risks. Improved internal firewalls to prevent fire from spreading between cells if one fails
• User-Level Safety Precautions
  • Use only manufacturer-approved chargers.
  • Avoid unattended or overnight charging with unsafe setups.
  • Ensure home electrical systems can handle high loads.
  • Get batteries checked after impacts.
  • Allow battery to cool after long drives before charging and keep charging areas clear.
• Strengthened Safety Standards in India
  • Bureau of Indian Standards (BIS) updated EV battery safety norms in 2023.
  • Under AIS-156 standards, batteries must:
    • Undergo tests for heat propagation
    • Provide at least five minutes for passenger evacuation in case of fire