The Importance of Battery Cooling Systems in Electric Vehicles

Key Takeaways

• The lithium-ion battery and lithium polymer battery are the two most common types of batteries in modern electric vehicles. 

• Overheating is one of the major causes that accelerates the rate of battery degradation in electric vehicles.

• The battery cooling system in electric vehicles regulates the temperature of the battery pack.

The battery cooling system in electric vehicles regulates the temperature of the battery

Conventional vehicles are based on internal combustion engines and require fuel for transportation. Considering the energy needs of the transportation sector, most countries import petroleum, and this covers a major share of the nation’s economy. However, electric vehicles utilizing electricity as their energy source support the economy as well as the energy security of the nation. As electric vehicles grow in popularity and usage, it will become more important to understand how they function—particularly how their battery systems work.

Electric vehicles depend on rechargeable batteries for mobility. As batteries supply electric power to the electric motors in electric vehicles, these batteries get heated and require some sort of thermal management system. The battery cooling system in electric vehicles regulates the temperature of the battery and other electronics systems. Let’s take a look at electric vehicles, how they work, and how engineers keep their batteries cool.

Electric Vehicles

The future of transportation is electric vehicles. Electric vehicles offer a noticeably better driving experience, with excellent torque, power, speed, and acceleration compared to traditional vehicles. Electric vehicles offer other advantages over ICE-powered vehicles such as zero fuel consumption, eco-friendliness, low maintenance, efficiency, and reliability.

The key reason behind these advantages is that the mechanical motion in electric vehicles results from the conversion of electrical energy. The combination of batteries, chargers, and motors makes this possible. Electric vehicles utilize rechargeable batteries for electric power and convert this power as per the requirements of the motor. When the battery drains out, the electric vehicle becomes static. Batteries are critical to ensuring the reliability of electric vehicles, so let’s take a look at the types of batteries used in electric vehicles next.

Batteries in Electric Vehicles

Electric vehicles rely on different types of rechargeable batteries. The lithium-ion battery and lithium polymer battery are the two most common types of batteries in modern electric vehicles. They have a high energy density compared to their weight. Nickel-metal hydride batteries are also used in hybrid electric vehicles. Lead-acid batteries are being used for ancillary loads in electric drive vehicles. 

The Need for Battery Cooling Systems in Electric Vehicles

Overheating is one of the major causes that accelerates the rate of battery degradation in electric vehicles. Heat generation makes the battery work hard and causes its performance to deteriorate over time. The direct current fast charging and rapid charging of the battery are not good for battery health, as the accelerated electric currents create higher temperatures.

The high temperature in the battery causes battery fluid evaporation and damage to the internal structure of the battery, which cannot be corrected. At optimal temperatures, discharge power availability, charge acceptance during regenerative braking, and battery health are at their best. The battery life, electric vehicle driveability, and fuel economy degrade as the temperature increases. Considering the overall thermal effect on the battery, a battery cooling system is of great importance in electric vehicles. 

Liquid Battery Cooling Systems in Electric Vehicles 

The battery cooling system in electric vehicles regulates the temperature of the battery pack. The battery thermal management in electric vehicles uses cooling loops that contain liquid coolants such as ethylene glycol. An electric pump circulates the coolant through the batteries. Radiators are included in the cooling loop to release the heat to the ambient. The battery cooling system in electric vehicles can be either passive liquid cooling or active liquid cooling. 

Passive Liquid Cooling Systems

In a passive liquid cooling system, the cooling power depends on the temperature difference between the ambient air and battery. The cooling performance can be improved by connecting fans behind radiators. 

Active Liquid Cooling Systems

An active liquid cooling system is effective when the ambient temperature is higher than the battery temperature or when the temperature difference is too small. The active liquid cooling system consists of two loops. The primary loop is similar to the passive liquid cooling system. The secondary loop is in the air conditioning loop. It consists of two heat exchangers that work as evaporators and condensers, respectively. A quick response from the battery cooling system in electric vehicles is essential for reliable electric drive mobility.

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