Tesla Megapack 2 and Megapack 2XL 2023

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BMS and TMS (i.e., no safety protections were in place). Thermal runaway did not propagate beyond the seventh cell within Tray 2 of the initiator module, nor did it propagate to the battery modules installed above. In addition, thermal runaway did not propagate to the target MP2 cabinets installed 6 in (150 mm) behind and to the sides of the initiating MP2 cabinet. Lastly, no flaming was observed outside of the unit during the test.
Figure 10 Cell surface temperatures recorded during UL 9540A unit level fire testing. Approximate Time to Thermal Runaway: Cells 1-3: 78 minutes; Cells 4-6: 93 minutes; and Cell 7: 105 minutes.
Target Battery Module Surface Temperatures
As shown in Table 4, surface temperatures of battery modules within the target MP2 cabinets did not exceed 174°C (345°F), the temperature at which thermally initiated cell venting occurs.3
3
FEI Project # 22035 Page 23 01/23/2023 22035-03R (MP2 and MP2XL FPE Report)
As determined by UL 9540A cell level testing (see previous discussion).