EV battery cooling: Why is it so important?

It’s no new concept. Heating and cooling create a fine balance between efficiency and inefficiency, determining the optimal conditions for maximum power output, and will also affect the longevity of an electric vehicle’s (EV’s) battery. 

Cooling in an internal combustion engine (ICE) is a critical process, as well as in EVs—although a more advanced system can manage it more effectively. Now that cars are becoming more digital, adopting artificial intelligence (AI) to manage the processes that are integral for upholding their specifications, temperature is easier to manage. 

Understanding the different cooling system types gives more appreciation to the solutions that are now more commonly used in EVs. 

First, there’s air cooling, which, unsurprisingly, uses air to cool the battery. This can be either active or passive, meaning the car either draws air from outside or in the cabin (passive), or will be supported by a heating, ventilation, and air conditioning (HVAC) system (active). Often, the latter solution uses no more than 1kW of cooling and can also be used to heat or cool the cabin. The components that power the EV, such as the HVAC system, motor, inverter, and battery, are optimised by a battery thermal management system (BTMS). 

The alternative option—one that is used in the majority of EVs—is liquid cooling. This is the process of using liquid coolant, either water, a refrigerant, or ethylene glycol, to reduce the temperature of the battery. 

The coolant liquid passes through tubes and cooling plates to distribute the cooling properties safely among the electrical components, carrying the residual heat to another component of the car, like a radiator or heat exchanger. 

Temperature affects EV function and charging 

EV batteries are capable of operating in relatively extreme temperatures. The case of heating and cooling is to optimise its range, lifespan, and charging capabilities. While a battery can withstand operating temperatures from -30℃ to 50℃, it works best at ambient temperature—which is where heat regulation comes in. 

During use, thermal management systems are pretty robust, but they can also be susceptible to ageing components, corrosion, leakage, and blockages. While the concept of heating and cooling is almost the same for every EV, each company has their own take on how best to apply it to their cars.