Why do lithium batteries catch fire?
One of the major risks associated with lithium-ion batteries is thermal runaway. This phenomenon occurs when the temperature of a cell rises uncontrollably, potentially leading to fire or even explosion. Understanding its causes and consequences is essential for battery safety.
⚠️ Secure your batteries now! Thermal runaway is a real risk, but it can be avoided with the right technologies. Find out how our LFP battery packs guarantee optimum protection.
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Causes of thermal runaway
Thermal runaway can be caused by several factors:
Electrical causes of thermal runaway
- Cell overload : Overloading may cause internal overheating.
Deep discharge followed by recharge : A cell that has been over-discharged and then recharged may suffer a short-circuit.
- Cell internal short circuit : This can be the result of cell ageing or a manufacturing defect. A battery pack manufacturer must take this risk into account in its safety analysis.
Thermal causes of thermal runaway
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Self-heating to exposure to an external heat source : A battery subjected to high temperatures can go into thermal runaway. Certain scenarios, such as an external fire, make it difficult to protect against excessive heat.
Mechanical causes
- Shock and vibration : Physical impact can damage the cell and cause an internal short-circuit. The design of the battery pack must ensure effective mechanical protection.
What are the consequences of thermal runaway?
When a cell goes into thermal runaway, the internal chemical reaction causes a rapid rise in temperature. This phenomenon can spread to neighboring cells, triggering thermal propagation. When this happens, it's difficult to stop the chain reaction.
Possible effects include:
Emission of toxic fumes (hydrofluoric acid - HF)
An outbreak of fire
An explosion
How to avoid thermal runaway?
Prevention is based on several levels of safety:
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Electronic management with BMS :
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Maintain cells in optimum temperature and voltage range.
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Charge and discharge current monitoring.
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Circuit disconnection in the event of overheating.
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Mechanical design of the battery pack :
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Shock and vibration protection.
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Mechanisms to prevent inter-cell short circuits.
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Protection against external heat sources.
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How to prevent thermal propagation?
Even when preventing thermal runaway, a battery pack manufacturer must anticipate the possibility of a cell reacting. There are several ways of limiting thermal propagation:
Reduced oxygen supply to limit combustion.
Thermal insulation between cells to contain heat and prevent chain reaction.
Safety valve to depressurize the battery pack to prevent explosion.
Choice of cell chemistry LFP (Lithium Iron Phosphate) cells are more stable than NMC (Nickel Manganese Cobalt) and generate less heat in the event of thermal runaway.
Reduced energy density in critical applications.
Early detection of thermal runaway by the BMS to alert the user and avoid a dangerous situation.
The safety of LFP CirculaCar batteries
Our battery packs contain a range of protections against runaway and thermal propagation, making them among the safest and most resistant on the market.
At Circulacar, we design LFP battery packs incorporating advanced thermal runaway protection.
No thermal runaway was observed in tests involving fire resistance for more than 2 minutes, mechanical shocks of more than 20g or crushing of more than 10 tons.
Fire resistance for more than 2 minutes
Shock tolerance over 20g
Crush resistance over
10 tonnes
We also install safety devices that stop any thermal propagation.
During tests involving nail penetration leading to thermal runaway of a cell, our packs showed effective resistance to the incident, limiting the consequences of thermal runaway to simple fumaroles, without flames or explosion. Our BMS also detects the departure of a cell in thermal runaway, securing the battery and communicating the event to the vehicle to warn the driver.
Our battery packs are specially designed to prevent thermal propagation in the event of a cell runaway. This performance ensures the highest possible level of safety for electric vehicles, providing peace of mind during use. Our technology far exceeds the requirements of strict standards such as UN ECE R100-3, which stipulates a minimum delay of 5 minutes between the detection of thermal runaway by the BMS and the onset of a hazardous event (heavy smoke, fire or explosion). With our battery, the hazardous event never occurs.
Understanding and preventing thermal runaway is key to ensuring the safety of lithium-ion batteries. By integrating advanced protection solutions, CirculaCar offers safe and reliable LFP batteries, minimizing the risk of fire and explosion.
If you are interested in our LFP battery packs or have any questions, please feel free to contact us. here !