Have you ever heard of lithium battery overheating? Is this a serious problem? What causes it? This is a question that many lithium battery enthusiasts or technicians are concerned about. This article really analyzes why overheating occurs. This may involve, for example, using an incompatible charger, extreme temperature environments, sometimes physical damage, or the load of the battery. Only by understanding these root causes can you better prevent them.
Battery overheating means that the battery temperature exceeds the temperature point that it is designed to safely withstand. As you know, each battery has its own safe and comfortable temperature range. When the battery overheats, the risk begins to gradually increase, as shown below:
First, it affects performance and life. When lithium batteries are exposed to high temperatures, the internal chemical reaction rate is accelerated, which speeds up battery aging. Over time, you will find that the battery is not as durable as before, the charging and discharging efficiency is reduced, and the overall life of the battery will be shortened, and it needs to be replaced in advance.
Secondly, there may be changes in appearance. The battery may bulge, which means the outer shell swells. This is a clear sign that there is a problem inside the battery and it must not be used.
The extreme case is thermal runaway. If the temperature is out of control, smoke may appear or even thermal runaway may occur. This is a chain reaction inside the battery. The temperature continues to rise and cannot be controlled. In the worst case, it may catch fire or explode.
What causes a battery to overheat
Overheating is usually not caused by a single reason, but the result of a combination of factors. The following are several key reasons for abnormally high lithium battery temperature:
Battery overheats when charging
The charging process is a stage in which the chemical reactions inside the battery are active. Improper operation can easily cause heat accumulation.
It is common to use the wrong charger, charging at the wrong voltage or current, or using a cheap, unreliable charger, which increases the risk of overheating.
Overcharging causes the battery to be too full, for example, if the charger is broken or the battery protection board fails, the battery keeps charging and the battery can’t bear it.
If the charging speed is too fast, exceeding the battery’s tolerance, it will also become hot.
Also, charging when the weather is too hot or too cold puts a strain on the battery.
Discharge process problems
Over-discharging the battery or charging it when it is completely dead can easily damage the battery, and it may overheat more easily the next time you charge it.
The starting current is too large. For example, if you use an ordinary battery to power a device with extremely high power, this requires the battery to discharge with a large current, so it naturally heats up quickly.
Physical damage
If the battery is broken, hit by something, or pierced by a sharp object, the internal structure will be damaged, which may cause short circuit and heat, which is very dangerous. So pay attention to whether the battery has physical damage.
Internal short circuit
Internal short circuit may be caused by minor defects during production, or the battery may age due to long-term use. Small thorns (lithium dendrites) may grow inside and pierce the isolation membrane, allowing the positive and negative poles of the battery to come into direct contact, causing a short circuit.
External short circuit
The positive and negative terminals of the battery are accidentally connected at the same time by external conductive objects (such as metal keys, coins, tools, jewelry, etc.). At that time, the current is very large and very hot.
High temperature environment
Lithium batteries generate a certain amount of heat when they are working. External high temperature environment will hinder the battery’s heat dissipation ability and further increase the battery temperature, making it easier to exceed the safe working limit.
The battery itself has defects
The design and manufacturing quality of the battery pack is directly related to its safety. If the BMS is not well designed, the components are of poor quality, or a fault occurs, it will not be able to cut off the circuit in time when danger occurs, and the battery will lose its most important safety barrier.
Even if the battery itself is of good quality and used properly, poor heat dissipation design (such as the battery pack is too tight inside, the device casing has insufficient or blocked heat dissipation holes) will cause the battery temperature to continue to rise and eventually overheat.
How to prevent lithium battery overheat
After understanding the various factors that may cause lithium battery overheating, we should focus on how to actively and effectively prevent these situations from happening. Following the following simple and key practices can significantly improve the safety of lithium battery use and extend its service life:
Scientific charging is the first line of defense. The charger must be used correctly and properly. It is best to use the original one, or the one recommended/certified by Hongyitai, and it must match the battery. Don’t use those unbranded and poor quality chargers for cheap, which are one of the main hidden dangers of charging accidents.
Try not to keep the charger connected to charge. Although our battery’s BMS has a protection function that will prevent it from bursting, it is a good habit to unplug it when it is fully charged, and it will also make you feel more at ease, especially if you don’t leave it charging all night without anyone noticing.
Charge at room temperature. When the weather is too hot or too cold, it is best not to charge outdoors or in places with large temperature differences. Charging at room temperature is the safest.
Never charge a damaged battery. If you see a bulging, leaking, or noticeable dents on your battery, don’t risk charging it and contact us directly.
Use it properly to get the best performance. Don’t always use up the battery before charging. It is recommended to start charging when the remaining power is 20%-30%.
Do not overuse the battery: When your device (such as power tools, drones, etc.) is running under high load and high power, if you feel that the battery or device is abnormally hot, you should stop using it and let it cool down.
Choose the right battery for your device: Make sure the rated discharge rate (C-rating) of the lithium battery you use can meet or even slightly exceed the maximum power requirement of the device. Using a low-rate battery to drive a high-power device is a typical mistake, which will cause the battery to be severely overloaded and heated.
Prevent physical shock: Protect your device and battery from strong impact, drop or crush. Minor damage to the internal structure may develop into a safety hazard in the future.
Check the appearance of the battery regularly: pay attention to any abnormal conditions such as bulges, dents, cracks, leakage, or connector corrosion. If any problems are found, stop using it immediately and consider replacing it.
Maintain a moderate storage charge: If you need to store lithium batteries for a long time, it is not recommended to fully charge or completely discharge them. It is generally recommended to keep the charge around 40% – 60%, which helps slow down battery aging.
Protect the electrodes from short circuits: When storing or transporting individual batteries, make sure that the positive and negative terminals do not accidentally come into contact with metal objects. You can cover the terminals with insulating material or place them in a dedicated battery box.
Trust reputable brands and factories: This is the most fundamental part of ensuring battery safety. Suppliers like Hongyitai focus on R&D, have strict production quality control processes and use high-performance battery management systems (BMS). High-quality batteries, mature production processes and fully functional BMS are the key to preventing overheating and ensuring safety.
What to do if a battery overheat
While the risks can be minimized through proper use and selection of quality batteries, it is equally important to know what to do in the event of a lithium battery overheating. Here are the safety steps to follow in an emergency:
Stop operation immediately. If the device is in use, stop running immediately. If it is charging, unplug it immediately.
Move to a safe area. If the battery or device is only hot and not emitting smoke or fire, and you can move it safely, carefully move it to an open area away from anything flammable.
Natural cooling. Place the overheated battery or device in a safe area and allow it to cool naturally.
Observe and evacuate. If the battery starts to smoke continuously, hiss, swell, or ignite, evacuate immediately. Do not attempt to extinguish an out-of-control lithium battery fire on your own.
Seek professional help. If the battery shows signs of smoke or fire, call your local fire department immediately.
Even if the battery eventually cools down and does not catch fire, the overheated battery must not be used again. Please contact the battery manufacturer or a professional battery recycling agency for disposal.
Conclusion
Most battery heating problems are preventable. The key lies in how you charge, use, store, and protect your battery. The most important thing is to choose a battery with excellent quality and safety design. We at Hongyitai have been focusing on producing high-quality lithium batteries and can provide you with customized lithium battery packs.
Generally speaking, temperatures exceeding 60 ℃ are too high for lithium batteries and may cause thermal runaway.
Suspend equipment operation and move to a cool and ventilated place until the battery temperature returns to room temperature.
Immediately disconnect the power and observe for any signs of expansion, leakage, or other damage to the battery. Do not attempt to touch overheated batteries with your hands to avoid burns.
Lithium ion batteries should not be exposed to temperatures exceeding 60 ° C (140 ° F). Under such high temperature conditions, there is an increased risk of thermal runaway, and even fire or explosion.
