Unfortunately, we regularly face car fires. We often see them by the roadside but also at home. In garages, for example, your car or lawnmower can easily catch fire.
Electric cars pose life-threatening risks as the cars can catch fire while charging. Pulling car loop blankets over the car fire extinguishes a burning vehicle within minutes. Fire blankets are not only suitable for car fires but can also be applicable for other vehicles such as bicycle batteries, motorbikes, forklifts, ...
What is a fire containment blanket?
A fire containment blanket (or fire blanket) is a blanket made of fireproof material, usually fibreglass fabric. It is suitable for use in non-extinguishable battery fires, for example in electric cars or electric bicycles, as it can withstand particularly hot temperatures. A fire blanket can reliably keep a fire under the blanket, thus providing long-term protection for the surrounding area.
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| Fire blanket electrical car | Fire blanket electrical bicycle |
How does a fire blanket work?
The use of extinguishing blankets for vehicle fires is already an everyday occurrence for many fire departments. The fire blanket is pulled by two firefighters over a burning conventionally powered vehicle and usually smothers the fire within a very short time.
The situation is different for fires involving e-cars. A battery can burn for several hours. The blanket acts as a fire barrier, protecting the surroundings from heat, smoke and, in the case of exploding battery cells, from flying parts. A fire containment blanket is therefore suitable for containing a fire. This is because it keeps the high temperatures away from the environment and cuts off the oxygen supply. When placed over the burning object, it reduces smoke development within seconds and prevents flames from spreading to the surrounding area. Conventionally burning parts are extinguished by the lack of oxygen and the battery can burn under the ceiling without major danger.
Why is it so difficult to fight a battery fire?
Dealing with electric cars is a special challenge for firefighters. This is because the energy storage units installed in the vehicle harbor a certain fire risk – after an accident, due to charging or design errors, or due to high temperatures. And even for up to 72 hours!
How does a battery burn?
A rechargeable battery contains many small lithium-ion cells. If one cell catches fire, the heat ignites the next cell. A chain reaction begins, the so-called “thermal runaway”. This chain reaction is difficult to stop. The battery would have to be cooled below approx. 70 °C. Difficult, for example, when it is installed in a car and not easily accessible for cooling measures.
Why can’t you smother a battery fire?
The oxygen required for a fire is already contained in the battery; it is released as part of the fire process. So it is ineffective to cut off a burning battery from the oxygen supply, the battery will continue to burn. Caution: Conventional burning parts can very well be extinguished by oxygen deprivation. Only the battery burns – and may reignite surrounding objects.
How does a battery fire react to water?
As part of the ALBERO project, the handling of alternative propulsion vehicles on ferries was considered. This involved investigating whether water from sprinkler systems could contain an accumulator fire. Result: No, the opposite is the case. The water actually fuels the fire.
Water can be used as a coolant to bring the temperature of the battery below 70 °C and thus interrupt the “thermal runaway”. However, considerable quantities are required for this. Tesla, for example, says that to extinguish a fire in its vehicles requires about 12,000 L of firefighting water.
What other new methods are being used for battery fires and how should they be evaluated?
1. Container for dipping the vehicle
A container is filled with water and the vehicle is sunk into it.
Disadvantages: high cost and total loss of the vehicle.
2. Extinguishing lance
A lance is driven into the accumulator with great force and water is selectively applied through it.
Disadvantages: Precise placement of the lance is difficult, often the battery is not easily accessible.
3. Plastic bag with water filling
With the help of a crane, the vehicle is hoisted into a kind of giant Ikea bag. Up to the height of the battery is filled with water.
Disadvantages: high effort due to crane and large water demand, system is complicated, high price and can be used only once.