Here is the abstract and summary for the provided transcript.
Abstract:
This document is a public safety advisory regarding the WHY2025 conference badge, identifying it as a significant fire hazard when used with the provided unprotected 18650 Li-Ion cells. The core issue stems from multiple critical design flaws in the badge's main PCB that create a high risk of a short circuit. These flaws include insufficient clearance between positive and ground copper traces (separated only by a thin solder mask), improperly sized pads for the cell holders, and numerous exposed electrical contacts. The problem is compounded by the fact that safer, "protected" 18650 cells are physically too long to fit in the holders, locking users into an unsafe configuration. Community discussion corroborates these findings, further criticizing the decision to power the badge with two parallel, user-swappable cells as fundamentally risky and unnecessary. The advisory strongly recommends against installing the batteries and suggests using a USB power source as a safer alternative.
The WHY2025 Badge: A Public Fire Hazard Advisory and Community Analysis
Core Warning: A public advisory warns that the WHY2025 badge is a fire hazard due to its power system. The author and co-signatories strongly recommend that users never install the provided 18650 Li-Ion cells in the badge.
Unsafe Batteries by Design: The badge is designed for two "unprotected" 18650 Li-Ion cells connected in parallel. These cells lack internal safety circuits and can deliver dangerously high currents if short-circuited.
Key Takeaway: A critical finding, confirmed in community discussions, is that commonly available "protected" 18650 cells are slightly longer and do not fit in the badge's holders. This prevents users from easily substituting a safer alternative.
Critical PCB Design Flaws: The badge's main circuit board contains several design oversights that create a high risk of a short circuit, even when the badge is off.
Insufficient Insulation: The positive (+) and ground (GND) copper traces are only 0.4 mm apart, separated by a thin layer of solder mask (~10-30 Β΅m), which is easily damaged and insufficient as primary insulation.
Incorrect Component Footprint: The pads for the cell holders are too small for the actual components used, meaning the positive tab can overlap or sit dangerously close to the ground plane, separated only by solder mask.
Exposed Contacts: Numerous exposed solder joints and the cell terminals themselves remain uncovered, creating a short-circuit risk from contact with metal items like zippers or jewelry.
Risky Parallel Configuration: The design allows two user-swappable cells to be used in parallel. Community members highlighted that if a user inserts a fully charged cell next to a depleted one, a large, hazardous current can flow between them, posing a significant risk.
Questionable Design Rationale: The use of two high-capacity 18650 cells was deemed massive overkill for the badge's electronics. Commenters speculate this was a shortcut to achieve long battery life without investing the effort in power optimization, a choice that prioritized convenience over safety.
Official Recommendation and Mitigation:
The primary recommendation is to return the cells or store them safely in a non-conductive enclosure.
The badge may be used safely when powered by an external USB power supply, which typically has its own short-circuit protection.
An attempt by the organizers to mitigate one risk by applying epoxy over some solder joints was deemed insufficient as it fails to address the fundamental design flaws.
Organizational Context: The public advisory was published as a "last resort" after multiple private attempts to convince the event organizers (IFCAT) to address the hazard were unsuccessful. The situation highlights a failure in the product design and review process for a device intended for public distribution.