Putting out electric cars is proving incredibly difficult. Even when submerged in water for more than a day, the fires are sometimes not extinguished. A tiny glass ampoule should change that.
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It is only a few millimeters long, made of wafer-thin glass and filled with a brown liquid: the E-Bulb. The E stands for electric, the Bulb for glass tube, and it is nothing but the smallest fire extinguisher in the world, especially for EVs. The German company Job developed the device, of which half a million are now produced every day. They are mainly used in sprinkler systems of underground garages, in factory halls and in the maritime industry.
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From 2024 standard in electric cars
“We have now found a new application for the fire extinguisher,” says Rüdiger Klug, head of development at Job. “Namely mounting it in the batteries of electric cars, to prevent a fire from breaking out.” The E-Bulb is currently being prototyped for that purpose and, if everything goes according to plan, the tiny ampoule should be standard equipment for electric cars from 2024.
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Mini fire brigade in the drive battery
The ampoule is placed in a so-called thermal fuse made of fire-retardant plastic. If its temperature rises above 165 degrees, it will burst and activate a circuit-breaking mechanism, lowering the voltage by tripping battery segments. This greatly reduces the risk of short circuits, electric arcs and injuries.
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At the same time, the ampoule injects a liquid into the thermal fuse. This extinguishes the arc flashes and thus acts as a mini fire brigade in the drive battery. The ingredient thus has a preventive effect. Before something worse happens and the real fire brigade has to arrive, the small glass tube has prevented a car fire.
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Battery fire can reach more than a thousand degrees
The ampoule must burst exactly at the limit of 165 degrees in order to activate the safety switch. At this temperature, batteries begin to decompose and gases escape. If there is no thermal switch – as is still the case with the current generation of electric cars – the battery catches fire. This usually has a dramatic end, because once batteries are on fire, extinguishing is no longer possible. More toxic gases are then released than with diesel and petrol models, while the temperature can rise to more than 1000 degrees.
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