Response from IFCAT: What Hackers Yearn 2025
My response to specific parts:
- The protection circuitry is on the carrier-board PCB adjacent to the cells. The short interconnects pass close to ground planes/components.
The interconnect is not short. One cell is on the left, when the the protection circuit is on the right. The thick trace goes across the board before it finally reaches its fuse. It is flanked by the GND plane on both sides, at 0.4 mm distance.
Because production had already started, the use of unprotected 18650 cells and the carrier-board layout, incl. the unprotected path from the cells to the protection circuitry on the PCB, could not be changed.
“Could not be changed”?! Of course you can change course. Just don’t use the cell holders and don’t hand out unprotected cells to lay people. Those measures don’t require any change to the badge itself.
Several options were discussed in the past few weeks, when there was still plenty of time. One option was to glue wooden 18 mm dowels in the cell holders. Another was to put a sticker over the cell holders. The badge can be powered using an external power bank, which should be much safer because those should come with the short circuit protection that part of the badge lacks.
It is still possible to just not supply the cells, and to warn people that they shouldn’t use the cell holders. There is also still time to ask visitors to bring their own power banks.
Doing the right thing has been possible, and is still possible. Pushing forward is a choice, and has literally nothing to do with the badge already being or having been produced.
The mitigations listed below were evaluated and adopted, and were communicated to the reporter prior to publication.
To reduce risk, the exposed battery contacts and the surrounding area will be covered with UV-curing epoxy.
It mitigates the largest risk, but not everything.
In my estimation, this moves the risk level from “will go wrong” to “might go right”. That’s still quite a large risk to take with visitor’s lives.
Furthermore, do not charge a badge unattended in a tent,
That’s a good idea, but unrelated to the specific issues.
The risk of a short circuit is still present when the badge is off and not charging.
and don’t throw it carelessly into your bag.
And don’t wear it on metal clothing, don’t put it in a bag that also has metal things in it, etc, etc.
For those who prefer to avoid the risks, powering the badge from a power bank is fully supported.
Also, maybe don’t pitch your tent next to people who think it’s safe enough. Fires have a nasty habit of expanding beyond the direct vicinity of the person who took the risk.
The functionality of the badge and the performance remain unaffected when powered externally.
Exactly! So why are we taking this risk at all then?