Too hot to handle? Challenges & Solutions in EV Battery Cooling

Electric vehicle sales are speeding ahead. The number of EVs sold in a week in 2021 was higher than the number sold in all of 2012. And by the end of this year, electric cars could account for 18% of total car sales by then.

A good battery is the heart and soul of an EV. And it is what decides if your EV is a market winner or an also-ran. No wonder, an EV battery engineer’s salary is about as much as a CFO’s!

Within this all-important sphere of EV battery engineering comes the vital question of battery cooling, which is what determines the durability, reliability, and performance of an EV battery, and therefore, of an EV itself.

Causes and impact of battery temperature variation

EV batteries generate heat during operation because of several factors such as battery chemistry, charging rate, and ambient temperature. This needs to be dissipated to prevent damage to battery cells.

The battery temperature must be maintained to optimise performance and extend lifespan. Most reports say that the ideal operating temperature for EVs is 21.5 C (70 F). If the battery gets too hot, the cells can degrade, and if the battery gets too cold, it can cause the electrolyte to freeze and reduce the output of the cells. Sometimes when there is a temperature increase in one cell it can lead to a chain reaction, damaging the entire battery pack (referred to as thermal runway).

Solutions for EV Battery Cooling

Ensuring cooling efficiency, space management, and cost-effectiveness – all begin with battery design. For instance, battery packs could feature cooling channels or passages that allow the flow of a coolant or air directly over the battery cells.

Some battery designs incorporate Phase Change Materials, or PCMs, that absorb excess heat generated by the battery during operation and release it as they change phase (e.g., from solid to liquid) to regulate the battery’s temperature and prevent overheating.

Battery pack design integrates cooling elements within the pack itself, improving heat dissipation. For example, some car manufacturers place heat pipes or cooling fins within the pack to extract heat from the cells and transfer it to the cooling system.

EV batteries can be cooled using air cooling (passive air cooling where either air from the outdoors or from the cabin is used to cool or heat the battery, or active air cooling where the air intake is from an air conditioner) or liquid cooling (more popular and where a liquid coolant such as water or ethylene glycol is used).

Both active air cooling and liquid cooling can help keep a battery from heating up – however, liquid cooling is considered more effective. That’s why many auto manufacturers such as Tesla and Ford use liquid coolants to keep control of the temperature inside the EV battery as well as advanced thermal management systems to regulate battery temperature.

The challenges keep coming, but so do the solutions, if you go have a reliable partner. Blue Star E&E has more than 40 years of experience in material testing for the automotive industry, and now we have extended our range of inspection solutions for the entire value chain of the EV. Collaborate with our team of experienced professionals and benefit from their extensive knowledge and technical expertise to ensure consistent quality, top performance, and higher safety of your EV batteries.