Page 221 - Çevre Şehir İklim İngilizce - Sayı 3

Orhan Topal

The other approach is that the high voltage drive battery is not damaged
and the fire has not yet spread to the battery. Assuming that the battery has
not yet been involved in the fire, traditional fire extinguishing methods should
be immediately applied to bring the fire under control without any delay. In
electric & hybrid vehicles, cooling is the best way to extinguish battery fires.
After the fire is extinguished, the burnt vehicle should be monitored for a
certain period of time. Even if there is no visible damages on the battery, the
chemical reactions inside the battery cells have the potential to start a fire
again (Blum et al., 2015; Kagermeier, 2020). In order to reduce the temperature
and therefore the risk of thermal spread to other cells, it should be taken
into account to cool the high-voltage drive battery, use as much coolant as
possible for this purpose. In this respect, the amount of fire extinguishing
fluid required to extinguish an electric or hybrid vehicle fire differs significantly
compared to an internal combustion vehicle fire (Blum et al., 2015). After the
responding to the incident, high voltage systems must be disabled before the
damaged electric or hybrid vehicle involved in the accident is taken away from
the scene of the incident (VDA, 2020).
Due to the pressure generated on the cell base caused by heat formation
or mechanical deformation occurring in the high voltage propulsion battery
after an accident (if it exceeds a certain limit), there will be gas output through
the ventilation openings. Since there is a varying amount of gas output
depending on the cell type used in batteries, the sounds it emits are among
the evaluation elements that should be considered in this regard (Geib et
al., 2020). Similarly, the odor emission caused by the electrolyte leak should
also be identified on the propulsion battery where the explosion occurred
(Doughty and Crafts, 2006). In addition, the use of portable gas detectors for
gas release will provide a significant benefit.
The cell temperature of the lithium-based high voltage propulsion battery
used in electric & hybrid vehicles is a good indicator for safety (Cabrera, 2016;
Geisbauer et al.,2020). As a method that can be used to measure temperature
the data to be obtained via the thermocouple to be connected directly to the
battery cells or the measurements made by means of a thermal camera can be
based on. In this scope, the reflections of other light sources (sunlight during
the day, special lighting elements during the night) along the chassis to the
metal surfaces should also be taken into account especially in cases of daylight.
It is essential to install appropriate cameras for temperature measurement with
thermal camera and to focus on the surface of propulsion battery which is not
exposed to an external light source. Moreover, it should be also taken into
consideration that there may be delays measuring the actual temperature value
inside the battery cells during the application of temperature measurement

206 Journal of Environment, Urbanization and Climate