Thermal Management Testing for Electric Vehicles

Pressure and Temperature Cycling: The Standard for EV Thermal Management Validation

This article was originally published in SENSOR+TEST – Das Innovationsmagazin, May 2026. Read the full article here: SENSOR+TEST May 2026, p. 106

Electric vehicles place extreme demands on their thermal management systems. Battery packs, power electronics, heat pumps, and electric drives all operate within narrow temperature windows — and maintaining those windows across thousands of operating hours is a serious engineering challenge. Unlike combustion engines, battery-electric vehicles have no continuous waste-heat source, meaning heating and cooling must be actively and efficiently managed at all times.

Even minor deviations from defined temperature ranges can reduce driving range, accelerate component aging, and compromise safety. That makes validating thermal management systems one of the most critical steps in EV development.

Why Thermal Management Systems Are So Complex in EVs

Modern electric vehicles don’t use a single cooling loop — they use several decoupled circuits operating at different temperature levels. The battery circuit typically runs between -40°C and +60°C, while high-performance electronics or heat pump systems can reach up to +140°C. Each circuit must be designed, tested, and validated independently, as well as in interaction with the others.

Components such as hoses, pipes, cooling plates, heat exchangers, pump housings, valves, and connectors are subjected to repeated cyclic pressure and temperature loads during normal vehicle operation. Rapid charging cycles, recuperation phases, and ambient temperature fluctuations cause recurring changes in pressure, temperature, and volume flow throughout the system. Over time, this mechanical-thermal fatigue can lead to material failure — particularly at transition zones between different materials or at joints and welds where differing thermal expansion coefficients create local stress concentrations.

Cyclic Testing: The Industry Standard for Thermal Validation

To address this, combined pressure and temperature cycling tests (access our whitepaper) have become the established validation standard for thermal components in the automotive industry. Unlike static burst pressure tests — which measure maximum single-load capacity — cyclic endurance tests focus on the reproducible simulation of realistic pressure profiles over a defined service life.

Our test systems use water-glycol mixtures as the test medium, covering a temperature range from -40°C to +140°C. This allows both cold-start conditions and high-load thermal scenarios to be accurately replicated. Pressure profiles can be programmed as sinusoidal or trapezoidal curves and tailored to specific load collectives. Depending on the application, test frequencies between 0.2 and 2 Hz are used, with flow rates of up to 60 l/min per DUT.

By compressing real-world pressure and temperature load collectives, our test systems can simulate several years of vehicle operation in a significantly reduced timeframe — providing a reliable, accelerated basis for lifetime assessment and component release decisions.

Modular Test Systems for Multi-Circuit EV Architectures

The test systems developed and manufactured by Poppe + Potthoff Maschinenbau in Nordhausen, Thuringia, are modularly designed to reflect the complexity of modern EV thermal architectures. Multiple independent fluid circuits can be operated in parallel, each at different temperature levels, to simultaneously represent the full thermal landscape of a vehicle architecture.

Volumetric flow and flow dynamics are precisely regulated and monitored. The rapid reconfiguration of the test setup allows individual components and complete subsystems to be tested under comparable conditions — increasing both development efficiency and the comparability of results across platforms and suppliers.

Data-Driven Lifetime Assessment

A reliable lifetime prediction requires the continuous recording of all relevant measured variables. Pressure curves are recorded with high temporal resolution to correctly capture dynamic load peaks. Temperature measurements at the inlet, outlet, and locally on the test object enable thermal gradient analysis and the identification of potential hotspots. Additionally, volumetric flow, differential pressure, and, where applicable, electrical parameters of active components are captured.

Changes in system behavior over time provide early indications of degradation processes. Rising pressure losses can indicate cross-sectional narrowing or particle formation, while changes in temperature distributions suggest deteriorating heat transfer. This systematic data capture forms the basis for robust lifetime models, design optimizations, and the assessment of safety reserves — taking validation well beyond simple functional testing.

Conclusion: The Key to Robust EV System Design

As electrification advances, the focus of development shifts from individual components to complex thermal subsystems. Managing cyclic pressure and temperature loads is becoming a decisive factor for the durability, efficiency, and safety of electric vehicle architectures.

Modular, scalable test systems with high-dynamic control and precise measurement technology provide the technological foundation for this, enabling realistic, accelerated simulation of vehicle operation and delivering the data needed to design robust thermal systems and sustainably validate electric vehicle architectures.

This article was originally published in SENSOR+TEST – Das Innovationsmagazin, May 2026. Read the full article here: SENSOR+TEST May 2026, p. 106

FAQ

Q: Why do EV thermal management systems require such extensive testing?
A: Electric vehicles operate multiple decoupled cooling and heating circuits at different temperature levels simultaneously. Components within these circuits are constantly exposed to changing pressures, temperatures, and flow rates — especially during fast charging, recuperation, and cold starts. Over thousands of operating cycles, this mechanical-thermal stress can cause fatigue at welds, joints, and material transitions. Thorough cyclic testing ensures these failure modes are identified and addressed before the vehicle reaches the market.

Q: How long does a cyclic thermal endurance test take?
A: By compressing real-world load collectives into accelerated test profiles, modern test systems can simulate several years of vehicle operation in a significantly shorter timeframe. The exact duration depends on the required number of load cycles, the test frequency (typically between 0.2 and 2 Hz), and the specific OEM or normative requirements the test aligns with. The goal is always to generate statistically reliable lifetime data as efficiently as possible.