Application

The first step in any response is to properly assess the situation: Is the vehicle involved in the accident a hybrid or electric vehicle with a lithium-ion battery?

External features of the vehicle often provide important clues: relevant lettering or markings, orange high-voltage cables, the absence of an exhaust system, or the word “Ready” on the display.

A visible charging port can also be a clear indication. Reliable information can be obtained by asking the person who reported the accident or the vehicle occupants, as well as by checking the license plate through the dispatch center.

If the vehicle is on fire, after conventional firefighting has begun—always while wearing respiratory protection—the second, decisive step in assessing the situation is: Has an exothermic reaction already begun inside the high-voltage battery?

Thermal runaway (see below), which generates extreme heat in a very short time, can be identified by typical signs: noise (hissing or whistling), dense smoke, flying sparks, and jet flames emanating from the lithium-ion battery, as well as an abnormal, pungent odor.

In addition, the thermal imaging camera provides valuable information by visualizing temperature increases and precisely locating areas of critical temperatures. If there are indications of a battery fire, the E-Löschlance® is deployed.

How does a lithium-ion battery catch fire?

However, if overcharging, a short circuit, mechanical damage, or high temperatures above 180 °C occur—for example, as a result of an accident—the layered structure of the metal oxides used breaks down. The result is what is known as thermal runaway. This releases large amounts of energy (exothermic reaction); elemental oxygen forms inside the cell, the electrolyte liquid evaporates, and highly flammable gases are produced. If these gases ignite, the lithium-ion cell catches fire.

Particularly critical: This process is self-reinforcing, as the lithium-ion cells generate the oxygen required for combustion themselves. The fire can spread to neighboring cells within a short time as temperatures rise rapidly—potentially spreading to the entire vehicle or the surrounding area.

Extinguishing Battery Fires

Fires involving lithium-ion batteries are extremely difficult to extinguish. They are typically tackled from the outside using large amounts of water to cool the entire battery and prevent the fire from spreading further. But this is precisely where the problem lies: when batteries are only slightly damaged, the actual source of the fire inside often remains out of reach. The robust, thermally insulated battery casing shields the cells—the water used to extinguish the fire barely penetrates the interior, and the cooling effect remains limited.

However, the water can barely reach the source of the fire in a battery that is only slightly damaged mechanically, and the cooling effect is also limited due to the thermal insulation of the battery housing. The result is an enormous waste of resources; often, several thousand liters of water are needed in a short period of time.

The E-Löschlance® is made of sturdy, reinforced stainless steel and is electrically insulated up to a voltage of 1,000 volts. It can be flexibly configured depending on the application: with a suitable extension, an E-spacer, and a connected D-hose for the water supply. A pressure reducer ensures a controlled discharge of the extinguishing agent at a rate of 40 liters per minute—ideal for specifically flooding the battery.

First, locate the installation site of the high-voltage battery and the appropriate point of entry using the emergency data sheet; a thermal imaging camera can also provide information on the exact location. Then position the lance at this point on the battery box and, while the extinguishing agent is flowing, carefully drive the lance tip into the battery box with a sledgehammer. Once it is correctly positioned (not too deep), the effect is quickly apparent: the extinguishing agent enters the cells directly and smothers the fire by flooding the battery box.

This allows burning lithium-ion batteries to be fought quickly, precisely, and with comparatively little use of extinguishing agent using the E-Löschlance®.

Effective Post-Extinguishing Care – Cool and Monitor

Even after the fire has been extinguished, vigilance is required. The extinguishing agent must continue to flow until all battery components have cooled sufficiently. Monitor the temperature of the extinguished high-voltage battery using a thermal imaging camera to prevent reignition.