Electric and hybrid commercial vehicles depend on thermal management to keep batteries, power electronics and electric drive components within their intended temperature ranges.
Unlike conventional cooling systems that primarily manage engine temperature, electrified drivetrains may contain several interconnected cooling circuits. A thermal fault can therefore affect charging performance, available power, battery life or overall vehicle operation.
For workshops, understanding these relationships is increasingly important when diagnosing electric and hybrid trucks, buses and vans.
What does the thermal management system control?
Depending on the vehicle architecture, thermal management can include the traction battery, inverter, electric motor, onboard charger and DC-DC converter. Cabin heating and air-conditioning may also interact with the same thermal architecture.
These components do not necessarily require the same operating temperature. Vehicles can therefore use separate cooling circuits, control valves, pumps and heat exchangers to distribute or remove heat as required.
Sensors and control units continuously monitor temperatures and adjust coolant flow or other thermal functions accordingly.
Battery thermal management
Traction batteries are particularly sensitive to temperature. Excessive heat can accelerate battery degradation, while low temperatures can reduce available power and charging performance.
Battery cooling systems are therefore designed to maintain cells within a suitable operating range. Depending on the vehicle, this may involve liquid cooling, refrigerant-based systems or other thermal-control arrangements.
Uneven temperature distribution within the battery can also be significant. Diagnostics should therefore consider temperature differences and sensor data rather than relying on a single overall temperature value.
Cooling the inverter and electric drive
Inverters generate heat while converting electrical energy between the battery and electric motor. Electric motors and other power-electronic components also require controlled heat dissipation.
Insufficient coolant circulation, restricted heat exchangers, pump faults or incorrect sensor readings can cause temperatures to rise. The vehicle may then reduce available power to protect the affected components.
This means that a power limitation does not automatically indicate a defective inverter or electric motor. The cooling system should also be included in the diagnostic process.
Common thermal-management problems
Typical faults can include coolant leaks, defective electric coolant pumps, blocked heat exchangers, malfunctioning valves, contaminated coolant and incorrect temperature signals.
Air trapped in a cooling circuit after repair can also interfere with circulation. Correct filling and bleeding procedures are therefore important whenever the circuit has been opened.
Because several components may share parts of the thermal system, symptoms can appear in a different area from the actual fault.
Diagnosis under real operating conditions
Some thermal problems only become apparent under high load, during rapid charging or at high ambient temperatures. A vehicle may therefore behave normally during a short workshop test but show power reduction during demanding operation.
Diagnostic data can help identify these conditions. Temperature values, pump operation, coolant flow and fault-code history should be evaluated together with the conditions under which the problem occurs.
This helps distinguish an actual component failure from a problem elsewhere in the thermal-management system.
Selecting replacement components
Cooling pumps, valves, sensors, heat exchangers and other thermal-management parts can vary between vehicle configurations and production generations.
OE numbers, VIN information and relevant system specifications should therefore be checked before replacement. A visually similar component may have different electrical characteristics, flow capacity or control functions.
Superseded parts should also be checked carefully, particularly where a newer component requires additional parts, revised installation procedures or software-related measures.
Conclusion
Thermal management is essential to the reliable operation of electric and hybrid commercial vehicles. Batteries, inverters, electric motors and charging components all depend on controlled temperatures to operate correctly.
When overheating or performance limitations occur, diagnostics should consider the complete thermal system rather than immediately replacing the component reporting the fault.
Correct diagnosis, vehicle-specific component identification and proper servicing of cooling circuits help prevent repeated repairs and support reliable operation of electrified commercial vehicles.
FalkePro – Commercial Vehicle Spare Parts
FalkePro specializes in the sourcing and B2B trade of spare parts for trucks, buses and commercial vans. We support workshops, parts distributors, fleet operators and transport companies with commercial vehicle spare parts sourcing across international markets.
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