How does EV stay cool?

Exactly — cooling the battery pack is one of the most critical functions in an EV, since lithium-ion batteries must stay within a narrow temperature window to operate safely and efficiently. Here’s a breakdown of the main battery cooling options you mentioned:

1. Phase Change Material (PCM)

• How it works: The material absorbs heat as it changes from solid to liquid (latent heat storage).

• Advantages:

  • Passive system, no moving parts.

  • Can smooth out temperature spikes.

• Limitations:

  • Heat absorption capacity is limited once the material has fully changed state.

  • Often used in combination with other cooling methods.

2. Cooling Fins

• How it works: Thin metal fins increase the surface area of the battery pack or module, allowing more efficient heat dissipation into surrounding air.

• Advantages:

  • Simple, lightweight, and low cost.

  • Works well with natural or forced air cooling.

• Limitations:

  • Air has low thermal conductivity compared to liquids.

  • Not sufficient for high-performance or high-capacity battery packs.

3. Air Cooling (Passive or Active)

• Passive air cooling: Relies on natural convection around the battery.

• Active air cooling: Uses fans or ducts to blow air through the pack.

• Examples: Early Nissan Leaf models used air cooling.

• Advantages:

  • Low complexity and cost.

  • Lightweight system.

• Limitations:

  • Poor heat transfer efficiency.

  • Limited effectiveness in hot climates or under heavy loads.

4. Liquid Cooling

• How it works: Circulates coolant (often a water-glycol mixture) through channels, pipes, or cold plates in contact with battery modules.

• Examples: Tesla, BMW, and most modern EVs use liquid cooling.

• Advantages:

  • High thermal conductivity and very effective at heat management.

  • Can integrate with the vehicle’s overall thermal management system (shared with motor, inverter, AC/heat pump).

• Limitations:

  • More complex and heavier than air systems.

  • Risk of leaks.

Summary:

• Phase change materials: absorb heat temporarily, best as a supplemental method.

• Cooling fins and air cooling: simple but limited, suitable for lower-power EVs.

• Liquid cooling: the most effective and widely adopted method for modern EVs, especially high-performance and long-range models.