It’s been well established that excessive heat buildup can critically damage the essential electronic equipment that keeps electric vehicles (EVs) operating properly. In today’s EV market, there is an increasingly important need for an ideal method for mitigating heat generated by powerful batteries. While most current vehicles are cooling their batteries with water-glycol systems (similar in nature to cooling traditional ICE engines), such a method has some fundamental limitations. A new solution is required.
The first part of this series examined why immersion cooling—a process by which the battery is submerged and operates within a bath of dielectric cooling fluid—has demonstrated significant potential as an ideal cooling method. Cutting-edge automakers and Tier I EV companies are beginning to focus their attention on this process for new EVs in the near future. In practice, immersion cooling today is only deployed in high-performance racing vehicles, but it is reasonable to expect that immersion cooling will be brought to mass production vehicles between 2025 and 2027.
But as with any fluid that helps a vehicle perform to its full potential, dielectric cooling fluids are not all created equally. Different OEMs have developed distinct EV architectures that will have likewise distinct cooling needs; off-the-shelf dielectric fluids may not be able to meet the evolving needs of every manufacturer. It’s more likely that OEMs will need to work with partners who can help formulate customised dielectric fluids to meet the specific hardware needs.
The importance of custom formulation
Dielectric fluids are not new and have been used in wide-ranging applications for years. But most available fluids are formulated with off-the-shelf fluids and chemicals and are not purpose-designed for EV applications. This means they may not be ideally suited to deliver the levels of performance that can be achieved—and that may be necessary—by custom-formulation approaches.
In practice, immersion cooling today is only deployed in high-performance racing vehicles
There is a better way forward for EV OEMs pursuing immersion cooling technologies for next-generation vehicles. Collaborative approaches between OEMs and lubricant manufacturers and formulators can help to identify specific needs for unique systems. This sort of customisation further allows OEMs the flexibility necessary to adapt as new EV battery and architecture design iterations are developed and brought to market.
Assistance from a custom-formulation partner can also help identify any chemistry and additive package tweaks during the formulation process, helping to optimise the fluid’s performance properties as testing is performed. And because immersion technology is new, there are many complexities that must be worked through. Currently, at least nine OEMs and 18 Tier I companies (such as radiator and other EV equipment suppliers) are working through this type of process in order to identify the best-performing dielectric fluids for their specific systems.
Performance properties of a dielectric fluid
What are some of the performance characteristics that OEMs should be looking to optimise in a dielectric fluid? While there are many variables to consider, a few of the most important include heat transfer, safety and durability. An ideal fluid will help warm up batteries quickly and keep them cool (below 50 degrees Celsius) to maximise battery life, range and output. This attribute helps to keep other electrical components cool to maximise efficiency, helping the vehicle get more from the battery overall. In terms of safety, dielectric fluids must work with the hardware to prevent battery ageing. Additionally, in the event of thermal runaway, the fluid must also prevent the failure from spreading throughout the battery pack. When it comes to durability, fluids must be selected and formulated to last the lifetime of the battery and be compatible with the polymers and seals. Dielectric fluids are not changed and serviced like other conventional vehicle fluids.
EV automakers seeking to seize the opportunity presented by immersion cooling should work closely with formulation specialists to identify the right dielectric fluid performance properties for their unique systems. Because most OEMs are only yet in the beginning phases of testing immersion cooling in mass-market production vehicles, a formulation partner with deep expertise in fluid technology can be beneficial in overcoming some of the initial challenges and hurdles associated with early-stage development.
It is reasonable to expect that immersion cooling will be brought to mass production vehicles between 2025 and 2027
There are indications that this emerging cooling technology will eventually become standard for most EV battery-cooling systems. As immersion cooling becomes more common in EV applications, the fluids necessary to keep the batteries cool will also need to evolve. It will be incumbent on lubricant manufacturers to be flexible enough to tweak their chemistries in partnership with automakers to adapt their fluids to this emerging technology.
Immersion cooling’s cost-effectiveness, combined with its safety profile, makes it a logical choice for EV OEMs in the future—and working with the right partner can help OEMs realise those advantages sooner rather than later.
About the author: Andy Richenderfer is a Senior Research Engineer at The Lubrizol Corporation