Battery overheating is an important issue that can occur during battery use, especially when there is high power output or prolonged use. Overheating can not only cause battery performance degradation but also pose safety risks, such as fire or explosion. Therefore, understanding the causes, symptoms, and prevention methods for battery overheating is crucial to extending battery lifespan and improving safety.
What is Battery Overheating?
Battery overheating refers to the condition where the operating temperature of the battery exceeds its designed safe range. Every battery has an optimal working temperature range, and when the temperature exceeds this range, the chemical reactions inside the battery can become unstable, leading to performance degradation and even potential hazards.
Consequences of Battery Overheating
The consequences of battery overheating can include:
- Performance degradation: Overheating accelerates battery aging, reducing its effective capacity, and shortening the battery’s runtime.
- Thermal Runaway (TR): High temperatures can trigger thermal runaway in the battery, leading to rapid temperature increases, swelling, and even fires or explosions.
- Battery damage: Prolonged overheating can damage the battery’s internal chemical composition, causing leakage or battery deformation.
Causes of Battery Overheating
The causes of battery overheating can vary, including:
- Fast charging or overcharging: Fast charging generates high currents within the battery, leading to excess heat. If the charging current exceeds the battery’s capacity, the battery temperature rises rapidly.
- Poor quality or degraded battery: Older or poor-quality batteries have increased internal resistance, which leads to heat accumulation and overheating.
- High external temperature: In hot environments, the battery’s heat dissipation capability is reduced, making overheating more likely.
- Improper use or excessive discharge: Batteries can overheat when discharged excessively, especially under sustained high loads.
- Battery Management System (BMS) malfunction: A failure in the battery management system may prevent proper monitoring of temperature and current, leading to overheating.
Symptoms of Battery Overheating
Common symptoms of battery overheating include:
Deformation or swelling:
Overheating increases internal pressure, potentially causing the battery casing to swell or deform.
Odor or smoke:
Overheated batteries may emit odors or smoke, signaling excessive internal reactions.
Abnormally high temperature:
The battery surface temperature will be significantly higher than its normal operating temperature.
Decreased charging or discharging efficiency:
Overheating can reduce battery performance, leading to slower charging speeds and reduced discharge capacity.
How to Prevent Battery Overheating
- Use the appropriate charger: Use a charger that matches the battery to avoid fast charging. Ensure that the charger’s output voltage and current align with the battery’s specifications.
- Avoid overcharging: Stop charging in time and avoid charging the battery beyond its maximum voltage.
- Maintain an appropriate operating temperature: Ensure that the battery operates within an ideal temperature range, avoiding use in high-temperature environments, especially in extreme heat.
- Use a Battery Management System (BMS): A BMS helps monitor the charging and discharging processes, ensuring the battery operates within safe parameters and preventing overheating.
- Regularly check battery condition: Regularly inspect the battery’s appearance and performance to identify and replace aging or damaged batteries promptly.
- Ensure good ventilation: Ensure that the device housing the battery has adequate heat dissipation space to prevent overheating.
How to Handle Battery Overheating
If a battery overheats, the following actions should be taken:
- Disconnect the power: If the battery overheats during charging or use, immediately stop using it and disconnect the power source.
- Cool the battery: Place the battery in a shaded, ventilated area, avoiding exposure to high temperatures.
- Inspect the battery: Check for any damage, swelling, or leakage. If the battery is damaged, dispose of it safely.
- Avoid contact: If the battery is severely overheated or smoking, avoid direct contact, and keep the battery away from flammable materials.
Which Batteries Are More Likely to Overheat?
Different types of batteries have different sensitivities to overheating. Generally,
18650 cylindrical NCM and LCO batteries:
These batteries are more prone to overheating due to the use of nickel-cobalt-manganese (NCM) and lithium cobalt oxide (LCO) chemistries, especially under high power output or in high-temperature environments.
LFP (Lithium Iron Phosphate) batteries:
LFP batteries have better thermal stability, and the probability of overheating is lower than with NCM and LCO batteries.
Large-format prismatic batteries (e.g., those used in electric vehicle battery packs) may also be more prone to overheating, especially without proper cooling systems.
Why Do Unused Batteries Heat Up?
Even when not in use, internal chemical reactions within a battery can still occur, which may lead to heat accumulation. Specifically, when batteries are stored for long periods, not fully charged or discharged, or stored in hot environments, internal resistance can cause temperature rise.
Can Battery Overheating Lead to Thermal Runaway (TR)?
Yes, if overheating is not controlled promptly, it can lead to thermal runaway (TR). This is an extremely dangerous process where internal chemical reactions intensify, causing a rapid temperature rise, which can result in fire or explosion.
Do batteries of different sizes affect heat dissipation?
Volume affects temperature transfer. For example, when we use an oven or microwave to heat different volumes of food for the same amount of time, the center temperature of the larger food will be lower. Similarly, the heat generated by the internal chemical reaction of the battery is transferred from the inside to the outside, and batteries of different volumes will perform differently. In Jin Liu’s study on the relationship between cylindrical battery size and thermal performance, it was revealed that cells with larger diameter-to-height (D/H) exhibited lower temperatures and lower thermal gradients.
Conclusion
Battery overheating is an issue that needs to be taken seriously, especially in high-power devices and electric vehicles. Understanding the causes and symptoms of battery overheating and taking appropriate preventive measures can effectively extend the battery life and improve safety. Proper charging, storage, use environment and timely inspection and maintenance are the key to avoiding battery overheating.
Post time: Dec-12-2024