How does battery cooling work?
Battery cooling works by removing heat from battery cells or modules to keep them within the temperature limits required for safe, reliable, and efficient operation. Heat is generated during charging and discharging through a combination of resistive and electrochemical processes. Depending on the battery system, operating profile, and environment, thermal management may be required to control this heat and maintain suitable battery temperatures. The sections below address the most important questions about how battery cooling systems work, why they matter, and what distinguishes industrial battery thermal management from standard HVAC approaches.
Why do batteries generate heat in the first place?
Batteries generate heat through several mechanisms during charging and discharging. Resistive losses, often described as Joule heating, are an important source: higher currents and internal resistance generally increase irreversible heat generation. Electrochemical and entropic effects also contribute to the cell’s overall thermal behaviour.
In lithium-ion battery packs, heat generation and temperature distribution are not necessarily uniform. Differences in cell position, cooling conditions, current distribution, and pack design can create temperature variations across the battery. Over time, battery ageing can change internal resistance and thermal behaviour, which also needs to be considered in thermal management design. This is why thermal management may need to maintain both suitable temperatures and sufficient temperature uniformity throughout the battery’s operational life.
What happens to a battery if it overheats?
If a battery overheats, performance, ageing, and safety can be affected. Prolonged exposure to elevated temperatures can accelerate degradation and reduce battery service life. At sufficiently high temperatures or under abusive conditions, additional failure mechanisms can develop.
Thermal runaway is a specific failure condition in which self-heating reactions become self-sustaining and heat generation exceeds the ability of the cell to dissipate heat. Depending on battery design and protection measures, thermal runaway in one cell can also propagate to neighbouring cells. In industrial and defense applications, where battery systems are integrated into vehicles, machinery, or shelters, the consequences can extend beyond the battery itself. Thermal management is therefore one element of battery safety, alongside cell design, battery management, electrical protection, mechanical design, and measures intended to manage abnormal or failure conditions.
What are the main types of battery cooling systems?
Battery thermal management systems can use several active, passive, or hybrid approaches, including air cooling, liquid cooling, refrigerant-based cooling, phase-change materials, heat pipes, and combinations of these technologies. The appropriate solution depends on the application.
- Air cooling: Uses natural or forced airflow to remove heat. It can provide a relatively simple solution where heat loads and temperature-control requirements allow it.
- Liquid cooling: Circulates coolant through cold plates, channels, or other heat-transfer structures thermally coupled to the battery. It can provide high heat-transfer capability and good temperature control in compact systems.
- Phase-change material (PCM) cooling: Uses materials that absorb thermal energy during a phase transition. PCM solutions may be used alone or as part of hybrid thermal management concepts depending on the application.
- Refrigerant-based cooling: Uses a refrigeration system to provide active heat removal, either directly or through an intermediate cooling circuit. It can be useful where the battery must be maintained below ambient temperature or where demanding thermal loads require active cooling.
The right approach depends on the application’s power density, ambient temperature range, available space, and reliability requirements. In demanding mobile machinery, liquid and refrigerant-based solutions can offer advantages where high heat-transfer capability and active temperature control are required, but the appropriate technology must be selected according to the specific battery and application.
How does liquid cooling keep battery packs at the right temperature?
Liquid cooling keeps battery packs at the right temperature by circulating a coolant fluid through heat-transfer components such as channels or cold plates that are thermally coupled to the battery modules or cells. The coolant absorbs heat, carries it away from the battery, and transfers it to a heat exchanger or another heat-rejection stage. The circuit may include pumps, valves, heat exchangers, sensors, and control functions depending on the system architecture.
In a battery cooling system for mobile machinery, the coolant circuit may form part of a broader thermal management architecture. Depending on the machine, batteries, power electronics, electric motors, or other components may use shared, connected, or completely separate thermal circuits. The control system can adjust thermal-management performance using temperature and other operating data to keep the battery within its specified operating conditions.
Heating may also be required in cold climates. A battery thermal management system can include heating or pre-conditioning capability where required by the battery chemistry, charging strategy, operating profile, and ambient conditions. This can help the battery achieve the required charging and power performance in cold conditions.
What is the ideal operating temperature range for lithium-ion batteries?
There is no single universal ideal operating temperature range for all lithium-ion batteries. The appropriate target and allowable limits depend on cell chemistry, cell and pack design, charging and discharging rates, battery age, operating profile, and the manufacturer’s specifications.
Low temperatures can reduce available power and charging capability, and charging under unsuitable cold conditions can increase the risk of lithium plating. Elevated temperatures can accelerate ageing and, at sufficiently severe temperatures or under fault conditions, contribute to safety risks. The battery thermal management system should therefore be designed around the specific battery’s defined temperature limits rather than a generic temperature range.
For industrial and mobile applications expected to operate reliably over years of variable use, both maximum temperature and temperature uniformity across the battery can be important design parameters. Thermal management requirements should therefore be derived from the battery system and actual operating conditions.
How is battery thermal management different from standard HVAC cooling?
Battery thermal management is different from standard HVAC cooling in its controlled target, thermal loads, integration requirements, and system architecture. Standard HVAC primarily manages the conditions of an occupied or enclosed air volume. Battery thermal management controls the thermal conditions of a battery pack or its modules, where both temperature level and temperature distribution can affect battery performance, charging, ageing, and safety.
In a battery thermal management system, the cooling system is thermally coupled to the battery through structures such as cold plates or coolant channels. The system must respond to changing heat loads driven by charging and discharging and may need to provide both cooling and heating depending on the battery and operating environment. In mobile applications, it must also be designed for the machine’s space, weight, vibration, and environmental requirements.
Standard HVAC systems are designed primarily around cabin or enclosure conditions, whereas a battery thermal management system is engineered around the thermal requirements of the specific battery, the application’s power and duty profile, and the machine’s operating environment. The two disciplines overlap in refrigeration, heat transfer, fluid handling, and controls, but their design requirements and controlled targets differ.
At Lumikko, battery thermal management solutions range from modular product platforms to application-specific configurations for electrified mobile machinery and heavy equipment. Systems are selected and adapted according to factors such as required thermal performance, operating conditions, installation space, and machine interfaces, and are manufactured in Finland.
Lumikko has also developed a tailored battery cooling solution for Sandvik’s battery-powered mining equipment. The system was designed to manage heat from batteries and charging equipment in demanding underground operating conditions.
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