. After concluding the investigation of the Nikola Tre BEV fires, the City of Phoenix's Fire Investigations Task Force division chief Daniel Cheatham toldthat the cause of the fire at Nikola's headquarters was officially declared to be"undetermined" and that there wasn't"any evidence at all that supports arson."
The Phoenix Police Department also opened an investigation into the fires and said it was analyzing evidence such as videos and witness tips. Both the fire and police departments are yet to publish final reports of their investigations. It's worth noting that internal Nikola documents revealed in June point to a possible issue with the Tre BEV's battery pack. More specifically, laser welding could puncture some cells in a module, causing the cells to corrode after just two test cycles and potentially generating excess heat. The startup toldin a statement that battery packs with weld issues did not make it into production semi-trucks.
also noted that both its internal engineering team and a third-party team have opened investigations to determine the root cause of the fires, and that the results would come out in several weeks.