"No doubt whatsoever that this bypasses the hot spring. In an overcurrent condition (ie. short circuit) the spring may collapse, but the brass would remain and would potentially continue the circuit..."
with this, I completely disagree. One tenth, one twentieth of the weight of the battery collapses that brass in an instant. This is purely hypothetical; but, if the spring were to collapse, there is absolutely no way that that brass would continue to push the battery up against the positive contact.
Sorry, I have to defend myself. Maybe I'm more sensitive to these thoughts due to my trade: electrician. Yeah, I'm haunted by short circuits or otherwise unsafe electrical practices. I consider every battery to be hazardous. Some of our e-cig batteries have a very serious potential to discharge a lot of energy in a very short time frame. Notice the word "potentially". In my trade, we have a saying: "a limp ..... in the wind", to describe any sort of loose bare metal that could POTENTIALLY short a circuit.
I fully agree that the weight of the battery would in almost every case open the circuit if the hot spring collapses, but that brass shim would just be a limp ..... in the wind. Meaning with nothing to secure it, on a portable device (moving in all orientations), knowing that metal sheets change shape as ambient temperature changes, there's no way to be absolutely certain it would not work its way toward a short. Call it low-risk if you need to, but there's still a chance of a short by my examination. Momentary shorts with light contact can be the worst kind since they often arc, which could damage the protective sleeve on a battery or deposit hot metal bits from exploding brass, compounding the danger. Any unwanted discharge should be avoided. I just don't like to play with fire.
Here's why I respect arc'ing:
Electric arcs produce some of the highest temperatures known to occur on earth - up to 35000 degrees Fahrenheit, or four times higher than the temperature on the surface of the Sun. Intense heat from an arc causes sudden expansion of air resulting in a blast. Copper (of which brass is comprised) expands during an arc flash event at a factor of 67000 times within a few milliseconds.
I'm not saying there is enough energy in an 18650 to cause the sort of expansion I just described, but why screw around. I'm speaking up because I feel it would be irresponsible to not at least mention the risks involved.
Just to be sure I'm not spewing from the ...., I've taken another good look at the OP pics. In that particular installation, it looks pretty damn safe. Previously I did not notice that part of the shim was actually secured by the hotspring assembly. Still something doesn't sit well with me on this particular modification. I think time would be better spent trying to come up with a fuse.
Even if you totally disagree with me, thanks for allowing me to have my opinion. Cheers.
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