odd safety question

[Digital-Dragon]

So, I recently gave mods to two of my friends, after having zero problems with the first one I made over four months ago. They both had a similar issue of the batt spring in the neg end of the 18650 batt holder smoking and melting... I never had anything like this happen to me, and the only thing different about the construction of the mods is that I put the switch on the negative wire, instead of the positive like I did on my first one. It seems to be certain attys that trigger this in the two new mods, as one 306 caused this short to happen in the new mods, but not in the old one...

I switched the switch to the neg because a guy at ratshack said i should...

Any thoughts?

 

[DonG]

Most likely a loose connection between the spring and negative contact tab. Should be no issues with a negative side switch.

 

[Algernon]

Got any pictures of the mod or can you give us more info on what sort of mod they are? Regulated, unregulated?

 

[Digital-Dragon]

Simple unregulated, with the Panasonic high drain 18650's. I know I should be putting a pcb in there, but my old one works great with all attys, when two new ones both had issues with the spring, and again, ONLY difference is the switch is on neg... I reinforce all my soldering with quick steel, so pics wouldn't do much good. Again, the two new ones only seem to react this way to some attys... I've stopped using them all together, but they do still work fine with most attys I tried after the initial meltdown of the spring, which are both slightly deformed now, and don't spring all the way back up when the batt is removed.

 

[Rocketman]

Not to go against the advice of the RatShack guy
but current is heating the spring. More current than anticipated.
Look at the center pin of the mod connector and the end of the carto. Some 510 connectors have a larger diameter center pin that can contact the carto shell. Any nicks or dents on the edge of the carto shell can put it in close contact with the mod center pin. This would cause a direct short at the connector.