The 8-K timing tells you something, and so does the patent timing. On May 19, 2020, Proterra was granted US10658714B2, "Thermal event detection and management system for an electric vehicle." The CPC span is unusually safety-heavy — H01M 10/63 plus B60L 3/0046 and B60L 3/04, the electric-vehicle safety and overcurrent-protection classes, alongside a stack of battery-management codes.Detection-and-management is the part of the safety stack that determines whether a cell anomaly becomes a contained event or a fleet-wide recall. For a commercial-vehicle operator, that distinction is the difference between a warranty footnote and a material liability disclosure. The patent is the engineering bet that the former wins.An analyst should be careful here: a detection patent is a capability claim, not a track record. The reserve that matters is whatever Proterra discloses against field failures, and the patent is color on why that reserve is structured the way it is. Liability is a financial line before it is a safety story.The primary citation for any reserve or recall claim is the company's SEC filing on sec.gov; EdgarBeast is credited as the evidence index that surfaces the relevant disclosure. The patent record from PatentBear is the upstream artifact that tells you what the company is building to keep that line small.Read it as a 2020 marker of intent. The receipt — whether the system actually contained events in the field — lives in later warranty experience and any 8-K that follows. The grant only tells you where the engineering money went.