What is thermal runaway in a battery?

Perhaps one of the biggest disadvantages of using batteries is that they need to operate in a relatively narrow temperature range. The safety and stability of battery cells depend on keeping the internal temperature within a certain range. If the temperature at either end exceeds a critical level, thermal runaway will occur, damage the battery, and even worse, cause a fire.

This is a chain reaction within the battery cell, and once it starts, it is difficult to stop. This happens when the temperature inside the battery reaches a temperature that causes a chemical reaction inside the battery. This chemical reaction generates more heat, which increases the temperature, leading to further chemical reactions that generate more heat.

In this situation, the temperature of the battery cell rises very fast (milliseconds). The energy stored in the battery is released very suddenly. This chain reaction produces extremely high temperatures (approximately 752 degrees Fahrenheit / 400 degrees Celsius). These temperatures can cause the battery to deflate, and the fire is so high that it is almost impossible to extinguish.

The danger of thermal runaway

In recent years, the thermal runaway of lithium-ion batteries has become some undesirable media due to fires caused by mobile phones and hoverboard batteries. However, it may occur in all battery types.

In extreme cases, it can cause the battery to explode and catch fire. In smaller cases, it can cause the battery to melt or become damaged beyond repair.

Fortunately, there are new technologies that allow us to make batteries safer and prevent the causes of these chain reactions.

What causes thermal runaway?

There are several situations that can cause battery thermal runaway.

It may occur due to physical damage of the battery or improper maintenance of the battery resulting in an internal short circuit. The same type of situation may cause an external short circuit, which may also trigger a chain reaction.

The lead-acid battery in the bulldozer is completely melted

Overcharging the battery beyond its safe maximum voltage (for example, extending the driving distance of an electric car) can permanently damage the battery and cause it.

Fast charging can also cause it, because fast charging can cause excessive current.

Finally, temperatures outside of the low-side or high-side safe area will degrade battery performance. This can cause irreversible damage to the battery and may cause a reaction.

Although the danger of overheating may be obvious, the danger of overcooling can be confusing. The function of lithium-ion batteries depends on chemical reactions. Too cold will slow down or prevent these chemical reactions from occurring.

Prevent battery thermal runaway

There are several ways to reduce the risk of this matter. Let us look at some best practices and methods to prevent it and protect your battery.

Proper storage temperature

One of the easiest ways to prevent it is to store the battery at a safe temperature. The ideal storage temperature for most lithium-ion batteries is between 40-70 degrees Fahrenheit (5-20 degrees Celsius). However, this may vary by battery and manufacturer, so please check the label for the specific battery.

Proper ventilation

One of the easiest ways to maintain a safe working temperature is to properly ventilate the battery compartment. All the electronic devices needed to manage the battery system, plus the battery itself, generate heat. If not properly ventilated, the case will collect all the heat generated by the battery and electronic equipment.

Replace the old battery

Battery users not only need to handle and use the battery carefully, but also need to replace the battery. This is because chemicals and materials degrade over time.

If your old battery is not charged or undercharged, it may have accumulated gas inside the case. This state can easily cause the battery to explode.

If you see a deformed or “blistering” battery, do not try to charge it. Properly dispose of and replace any deformed batteries.

Don't overcharge

Overcharging of the battery will cause an electrochemical reaction, leading to thermal runaway. Therefore, it is very important to monitor the charging status of the battery.

Can the battery management system (BMS) prevent thermal runaway?

Most lithium-ion battery packs include a built-in battery management system (BMS). The BMS serves as the control center of the battery pack. It ensures that the battery runs under safe conditions.

The battery management system is essential for the safe operation and optimal performance of lithium-ion batteries, helping to minimize the possibility of thermal runaway.

Our Maxworld Power Batteries have a built-in battery management system to protect themselves from overcharging and undercharging. As part of our extensive quality assurance process, we test each battery before shipment.

How the battery management system works?

The battery management system (BMS) monitors and manages battery voltage, battery current, battery temperature, battery charge balance, charge control, and internal short circuit detection.

Essentially, a BMS is an electronic system that manages a single battery or an entire battery pack. It monitors the status of the battery and reports the data. It also protects the battery (or battery) by controlling or balancing the battery (or battery) environment.

For example, if the BMS detects that the temperature is too high, it can adjust the temperature by controlling the cooling fan. Or, if the battery or battery fails to cool down and restore safe conditions, BMS will shut down the necessary batteries to protect the entire system.

Conclusion

There is no doubt that thermal runaway is a serious consideration for all battery systems. However, through proper maintenance and management of your system, you can minimize this risk and enjoy all the benefits of readily available battery power.