Table of Contents
- Why is battery thermal management important?
- Overview of Four Cooling Methods
- Phase Change Material (PCM) Cooling
- Heat Sink Cooling
- Air Cooling
- Liquid Cooling (Direct and Indirect Cooling)
- Comparison: Which Cooling System Is the Most Effective?
- Coolant Requirements for Different Cooling Systems
EV Battery Thermal Management System
Importance of Battery Cooling System
Advances in battery technology have increased power output and reduced charging frequency in EVs. Yet, a critical safety challenge persists: designing an effective cooling system for EV batteries.
During discharge, heat builds up—and higher discharge rates generate even more heat.
Battery operation relies on voltage differentials. Elevated temperatures excite internal electrons, diminishing the voltage gap between terminals.
Since batteries function only within a narrow thermal range, a well-engineered car battery cooling system is essential to maintain optimal performance. The system must keep the battery pack between 20–40°C while ensuring internal temperature variations stay within 5°C.
Excessive temperature differences disrupt cell balance, leading to inconsistent charge/discharge rates and accelerated degradation. Worse, overheating or uneven heat distribution can trigger dangerous failures—capacity loss, thermal runaway, or even fire hazards.
Which battery cooling system is best for electric vehicles?
Battery thermal management is still a hot topic in EV research—and here at Guchen, we're constantly improving our systems to help you get safer, more efficient performance.
There are currently four main battery cooling methods:
1. Phase Change Material Cooling (PCM)
2. Heat Sink Cooling
3. Air Cooling
4. Liquid Cooling (Direct and Indirect)
1. Phase Change Material (PCM) Cooling
By altering from solid to liquid, phase shift materials absorb thermal energy. Under the phase change process, the material can absorb a lot of heat with a low temperature.
Advantages: Able to meet battery cooling needs.
Disadvantages:
• The volume change during the phase change is large, which limits its application.
• It can only absorb heat but cannot effectively conduct it away, so the overall cooling effect is not as good as other systems.
• Suitable for building temperature control systems, but not for automotive battery cooling.
2. Heat Sink Cooling
Through larger surface area, the heat sink improves the heat transmission rate. From the battery pack to the heat sink, heat is transferred firstly convectively to the air.
Advantages: Its high thermal conductivity and ability to provide efficient heat dissipation help here.
Disadvantages:
• Usually used in internal combustion engine automobiles, it has been progressively eliminated in electric vehicles
• it adds needless weight to the battery pack and is not optimal for electric vehicles.
3. Air cooling
Air cooling uses the principle of convection to remove heat from the battery pack. Air flows over the surface of the battery and removes the heat emitted by the battery.
Advantages: Simple structure and easy to implement.
Disadvantages: • Low cooling efficiency and more primitive than liquid cooling.
• Poor safety in high temperature environments.
• Early electric vehicles (such as Nissan Leaf) used air cooling systems, but due to safety issues, most car companies have turned to liquid cooling.
4. Liquid cooling (direct cooling and indirect cooling)
The thermal conductivity and heat capacity of liquid coolants are much higher than those of air, so they have better cooling effects, more compact structures, and more convenient layout methods.
Advantages:
• The cooling effect is the best and can keep the battery temperature within the appropriate range.
• The structure is compact and easy to integrate. Disadvantages:
• There is a risk of coolant leakage, and special attention should be paid to sealing.
• Coolant handling must comply with environmental protection requirements. For example, improper handling of ethylene glycol may pollute the environment.
• Currently, brands such as Tesla, Jaguar, and BMW all use liquid cooling systems.
Comparative Study of Electric Vehicle Cooling Methods
• Air cooling system consumes 2-3 times more energy than other methods.
•Indirect liquid cooling has the lowest maximum temperature rise and the best control of temperature difference.
• Heat sink cooling adds 40% extra weight to the battery cell, limiting its application in electric vehicles.
• Indirect liquid cooling is more feasible than direct liquid cooling, although the cooling efficiency is slightly lower.
Key factors that determine the performance of battery cooling systems include:
• Temperature range and uniformity
• Energy efficiency
• Size and weight
• Ease of use (installation and maintenance)
Requirements for liquid coolants
Indirect liquid cooling
• Similar to traditional internal combustion engine cooling systems, liquid coolant is circulated through metal pipes to dissipate heat.
• Anti-corrosion additives are required to protect metal pipes, gaskets, connectors, radiators, etc. in the cooling system.
Direct liquid cooling
• Directly cooled batteries are in direct contact with the coolant, so a coolant with low or no conductivity is required.
• It is still in the research and development stage and has not yet been adopted in mass-produced models.
• Deionized water or non-salt-based coolants may be used in the future to reduce conductivity and improve safety.
Future development of BTMS for electric vehicles
Longer battery life and more power output are becoming more in demand as electric cars evolve. The battery thermal management system must dissipate heat more effectively to satisfy quicker charging and discharging rates and higher heat generation, therefore meeting this need. As GUCHEN technology is constantly iterated upon and developed,
BTMS will grow in a more intelligent, sustainable, and efficient path.
At present, liquid cooling is the most effective and practical way to cool batteries, and future innovations in battery technology and coolants will further enhance the safety of electric vehicles.
