## 3 Results  
### Results of BEV Large-Scale Fire Test 1  
The experiments were carried out under atmospheric conditions (Table 5), with intention to repeat the full-scale fire test on the BEV.  
The experiment started at 09:50:30 with the real-experimental time = 0 s. At the beginning of the experiment, the external source of a 300 kW propane burner was inserted into the damaged LIB (Figure 3a). The process of heating took 25 min, and its subsequent initiation was accomplished at 10:15:00 (Figure 3b).  
Figure 3: Experiment preview: (**a**) Time 0 s, inserting the external initiator into the damaged cover of the EV traction battery; (**b**) real experimental time 1500 s (25 min), action of the external flame.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Monitored Parameters** & **Values** \\ \hline Ambient temperature (\({}^{\circ}\)C) & 23.5 \\ Pressure (kPa) & 101.3 \\ Humidity (\%) & 56 \\ Wind velocity (km.h\({}^{-1}\)) & 0.35 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Conditions of the experiment.  
The temperature-time curves (Figure 4) quantify the events taking place during the experiment.  
The most interesting temperature development is on thermocouple T1, located 10 cm above the edge of the damaged cover. After 25 min, the temperature on thermocouple T1 increased by 80 \({}^{\circ}\)C within 10 s. Then, for the next 10 s, it increased by 250 \({}^{\circ}\)C. Furthermore,  
Figure 4: Temperature changes during the fire of the EV traction battery. The green rectangle represents the section shown in detail in Figure 5, and the orange rectangle represents the section shown in detail in Figure 11a.  
Figure 5: Section (purple in Figure 1) of the temperature–time curves of the experiment Test 1 within time frame from 10:15:03 to 10:18:53.  
within next 10 s, temperature raised again by 250\({}^{\circ}\), and within 1 min, reached a temperature of 900 \({}^{\circ}\)C (Figure 5). Within next 30 s, the temperature reached a value of 1009 \({}^{\circ}\)C, and after another 10 s, it reached the maximum temperature of the experimental fire, 1056.9 \({}^{\circ}\)C (Figure 5). Thermocouple T2 copied the values of thermocouple T1 with a time delay of 1 m 50 s, because its position is 20 cm further from the place of initiation of the EV traction battery. Based on the values of the thermocouple T3, we can conclude that the released heat does not spread at 50 cm during the observed time interval.  
The 3 min interval of the developed fire (Figure 6) was ended by removing the external 300 kW propane burner from the damaged part of the electric battery. This fact was automatically reflected in the temperature values measured using thermocouples T1 and T2 (Figure 5).  
Interestingly, the temperature course on thermocouple T3 was placed at a distance of 50 cm from gap 1. A slight temperature jump (92 \({}^{\circ}\)C) on thermocouple T3 occurred in the 38 th minute. At the indicated time, the secondary development of the fire occurred, which passed into the phase of a fully developed fire (Figure 7). Thermocoules T1 maintained a temperature of more than 900 \({}^{\circ}\)C, and T2 maintained a temperature of more than 750 \({}^{\circ}\)C.  
After 59 min real experimental time, a sharp drop in temperature (76.5 \({}^{\circ}\)C) occurred in thermocouple T1. Again, a time delay (60 s) appeared on thermocouple T2. It is possible to assume that the combustible components (electrolyte, cathode) present in the electric battery burned, and from that time point, the temperature dropped to the ambient temperature. The exception was with thermocouple T1, where the temperature dropped to 43.3 \({}^{\circ}\)C.  
Figure 6: Photo documentation of Test 1 within a time frame from 25 min to 28 min, real experimental time 3 min. Legend: The first row of images represents the course of the BEV fire in the first minute after 20 s (20, 40, and 60 s), the second row is the second minute after 20 s, and the third row of images is the progress in 3 slightly after 20 s.