As electric vehicles (EVs) evolve, thermal management has become a defining engineering challenge. From protecting battery performance during fast charging to ensuring component durability across a wide range of temperatures and environmental conditions, the thermal system is now central to both safety and efficiency.
This means engineers are being asked to solve for higher voltage architectures, energy-efficient flow control, and increasingly stringent material standards, all within tight packaging constraints.
Dominic Petri, Design Engineer at TLX Technologies.
We recently spoke with Dominic Petri, Design Engineer at TLX Technologies, to discuss how component-level engineering is shaping the future of EV thermal systems. The company partners with OEMs and Tier 1 suppliers to develop application-specific thermal control technologies for electrified platforms.
Petri brings a detailed engineering perspective to the conversation, with insights on the physical principles, design tradeoffs, and control strategies that drive innovation in EV thermal systems.
In this Q&A, he explains how smart valves help manage rapid thermal shifts, why coolant flow precision is vital for system stability, and what testing and simulation methods ensure reliability under real-world conditions. He also shares his outlook on emerging trends, from material selection in light of PFAS regulations to advanced battery cooling methods like refrigerant and dielectric-fluid immersion.
Here’s what he had to say…
What are the primary challenges EV manufacturers face when designing thermal management systems for high-voltage battery packs?
In ICE vehicles, thermal management systems are designed to use the excess heat from combustion to bring the engine up to proper operating temperature and warm the passenger compartment. Any excess heat is dumped into the environment by circulating coolant through a radiator. Because the internal combustion engine will start and run at cold temperatures and heat up quickly once running, the thermal management system only needs to perform one function: keep the engine from getting too hot.
The thermal management system in an EV is much more complex. It will typically control the temperatures in multiple components, such as the drive motor, the power electronics, and the traction battery. In many EVs, radiative cooling isn’t adequate. Vapor-compression refrigeration and active heating are often needed as well.
Thermal management in EVs is further complicated by the fact that the batteries perform best when kept within a relatively narrow temperature range. For Li-ion batteries, that’s between 15˚ and 35˚C.
When the battery is too cold, the chemical reactions that generate electricity slow down. This causes slower charging speeds and reduces charging capacity. To prevent this, a heating system is needed to warm the battery to its optimal temperature.
If the battery gets too hot, the chemical reactions can speed up uncontrollably in a process known as thermal runaway. When this happens, the battery cells generate more heat than can be dissipated, creating a kind of broken feedback loop. The excess heat speeds up the chemical reactions even more, which produces even more heat. When this self-perpetuating cycle reaches the critical point, the battery will either explode or catch fire and produce large volumes of toxic smoke.
Drivers are also demanding faster charging speeds, which is one of the more dangerous sources of heat for EV batteries. This means that the most capable cooling must be available when the vehicle is parked and plugged in. Instead of just a radiator and fan, the vehicle needs powered cold sources, such as a condenser or chiller, that are far more powerful than what is typically used to air condition the cabin.
Electric vehicles require precise thermal management to maintain battery performance, especially during fast charging.
It must be kept in mind that the power to run these heating and cooling systems comes from the battery itself, and its use can reduce vehicle range, so these systems must be energy efficient.
What considerations go into selecting materials for thermal management components, particularly in EV environments where durability and heat resistance are critical?
Multiple factors need to be considered when selecting materials: chemical compatibility with cooling media and lubricants, resistance to environmental salt and water, and expansion due to temperature and moisture absorption.
In addition to engineering considerations, there are the existing and pending material regulations of any country where the component might be sold. For example, the looming regulations driving the elimination of PFAS are concerning.
Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals widely used for their durability and resistance to heat, water, and chemicals. However, due to their persistence in the environment and potential health risks, global regulations are increasingly restricting their use in engineered materials.
How do pressure and flow control valves contribute to maintaining the efficiency and safety of EV thermal systems?
By modulating flow, valves ensure systems operate at the optimum temperature and prevent thermal overshoot and undershoot, which can lead to energy waste or insufficient cooling. They also allow for zoning, which prioritizes cooling for critical systems, like the battery or power electronics, while cutting back on less critical systems, like the cabin heater. This advanced flow control reduces parasitic losses by running pumps and chillers only when needed. Less power draw equates to extended vehicle range.
What advancements in valve technology have the most potential to address overheating issues in compact EV designs?
For the last 90-plus years, internal combustion engines have used wax-actuated thermostats to control the cooling of the engine. While these are simple in design, durable, and offer proportional control, their ability to control flow is equally as simple. When the fluid is cold, they close; when the fluid warms, they open.
New “smart” valves can be controlled by the vehicle’s electronic control unit (ECU), which continually monitors system performance and can dynamically adjust flow in real time based on thermal demand. Their faster response times are ideal for mitigating thermal spikes caused by fast charging and sudden acceleration.
These valves can be designed with more complex configurations, providing more accurate flow control throughout the system. For example, four-way switching valves can be used to switch between hot and cold for the heating and cooling of passenger compartments.
A four-way switching valves enable dynamic routing of coolant flow in EV thermal systems, allowing precise temperature control across batteries, power electronics, and cabin components.
Three-way switching valves can be used to completely divert and combine fluid to and from radiators, chillers, and heaters, depending on the system’s needs. Three-way proportional valves offer precise flow control to temperature-sensitive components like batteries.
Having the right predictors of catastrophic failure at the system level, combined with the right feedback systems on the valves at the component level, will lead to better prevention and detection of looming problems. Additionally, the design of fail-safe conditions at the valve level will prevent catastrophic component failures in the event of severed communication or even power loss from the control system.
What testing and validation processes are used to ensure that thermal management components meet the demanding performance requirements of modern EVs?
Several rigorous tests cover all aspects of performance. Basic function tests ensure that the valve can communicate with its corresponding control module. This communication includes the valve’s ability to receive commands and send feedback. Fluid performance tests are also conducted, which include pressure drop and cross-flow leakage.
The valve also has to be able to handle the wear and tear of a vehicle-mounted device. So, tests are conducted to ensure the valve’s ability to perform reliably under conditions that include vibration, shock, dust, salt spray, humidity, exposure to chemicals, and a wide range of temperatures.
Finally, electromagnetic compatibility and electromagnetic interference tests are performed to ensure that the valve is not affected by abnormal electrical signals from other components or systems and that it does not interfere with those systems.
Can you please explain the role of precision control in managing coolant flow and heat dissipation within an EV powertrain?
Different components can have different thermal management requirements. Precision control ensures that heat is removed efficiently, selectively, and safely, preserving both component performance and longevity.
Batteries need tight temperature control to function efficiently, while power electronics can generate spikes of heat under load. Motors can produce localized heating that may require higher flow rates to manage than other systems. All of these need active cooling that can react accordingly.
With EV adoption increasing, what trends do you see in the design and implementation of thermal management solutions to support faster charging capabilities?
An EV’s battery needs to be within a certain temperature range to charge effectively without premature degradation of the battery cells. At colder temperatures, it also charges more slowly and suffers from reduced charging capacity.
Because of this, some manufacturers will precondition the battery by warming or cooling it to the ideal temperature before charging. This temperature must be maintained throughout the entire charging cycle. The BMS, along with other control modules, plays an important role in this process, so active valve control and proper system feedback are a must.
The drive to reduce charging time is revealing another thermal management challenge. The high thermal loads produced by faster charging are causing some manufacturers to move away from liquid cooling to direct refrigerant or dielectric-fluid immersion cooling.
How can simulation and modeling optimize thermal management systems, and how can engineers best leverage these tools in their designs?
Simulation yields reduced costs, more efficient systems, and faster development. Hundreds of configurations can be designed and simulated in the time it takes to develop one physical prototype and test the system. Moreover, using a virtual component for simulation is much less costly than having it physically produced in small volumes for testing.
Computational fluid dynamics (CFD) simulation can be used to model fluid flow through valves, cooling plates, piping, and heat exchangers to optimize flow and pressure drops. Finite element analysis (FEA) simulation can be used to ensure valve housings, coolers, and other system components can withstand pressure spikes in the system.
Multi-physics simulation can be used to model the interaction between fluids, thermal, and electrical components at the component or system level.
What do you foresee developing in terms of advanced systems or components for EVs in the next few years?
There’s a lot of work being done to develop improved battery chemistries and recycling techniques. Both of these are important for achieving the goals that EVs were initially intended to reach.
In terms of battery chemistry, Li-ion batteries have some limitations, and research into new battery chemistries shows promise in overcoming these, particularly concerning charging speed, storage capacity, and safety.
Recycling techniques have to be improved as well. Li-ion batteries that are no longer serviceable can’t just be thrown away, and simply storing them isn’t a real solution. Better recycling will reduce waste and make it easier to produce new batteries.
There’s also considerable effort being put into developing better fire suppression systems and strategies. Li-ion fires are hazardous and extremely difficult to extinguish. This is because the battery’s electrolyte is flammable, and thermal runaway produces heat and oxygen, so the fire is self-sustaining. Even when it is possible to extinguish a fire, this doesn’t prevent thermal runaway from continuing in other damaged cells, causing reignition later.
Filed Under: Batteries, FAQs, Q&As