Got me curious so I searched around. The spring for the top pin supplies contact tension on the battery without having to bear down on the battery with the cover. When exceeding design specs while sub-ohming the spring heats like an internal heat coil. The solution is to remove the spring and replace it with a conductive spacer. The pin is adjusted to slightly lower then battery length and the cover is torqued down to the battery to make contact with no give. No error or expansion room for the battery. Sounds like a penny in a plug fuse fix. Sure it works but does the battery need the expansion space? Have not yet studied the battery venting system and the potential that cap crush damage may have on it. Penny for your thoughts?
With the pin removed there is no expansion space, but to be honest this is the first time I've ever heard this issue addressed before. There's already vents (and pretty significant ones) on the Hades which are there to relieve pressure in the event of a battery failure, I'm not qualified to say it doesn't need "expansion space" but I am qualified enough to say pretty much no other mech on the market has "expansion space" either, so removing the pin doesn't put you in a situation you wouldn't already be in with any other mod.
Mechs with floating center pins hold the battery tight once the atty is screwed down, so the battery is "squeezed" in there without any expansion space short of blowing the atty off. Other mechs use a system much like the Hades, but without the pin, where there is simply a threaded post (or two) that make contact and squeeze the battery when it's assembled. I know there are a few mechs with spring-held batteries but they aren't that common.
Another thing to consider is the whole pin assembly is secured to the top cap via a thin plastic coupler. If there was any extreme heat and/or pressure inside that mod that plastic coupler is going to fail quickly, relieving any pressure it exerts on the battery. But as I mentioned before, once the pin is removed the Hades functions like any other mechanical out there, so if it's dangerous to remove the pin than 90% of mechs on the market are equally dangerous.
For people having issues with connectivity once removing the pin:
Are you adjusting the post? The Hades tehcnically has a 3-part 510 center pin, with the spring-loaded pin removed you still have the ability to adjust the length via the threaded secondary portion of the post. The bottom part can be unscrewed from the top part taking up the space made by the pin's removal.
Removing the pin can also fix the hot-button issue mentioned before, even though it's on the opposite end of the mod. This is because the only thing pressing the battery down against the button is that weak tiny little spring. When you press the button, the battery moves upwards, shifts around, and you don't get a good connection between the negative contact and the battery's terminal because there isn't enough pressure.
You've got resistance in the button assembly... as in, poor electrical conductivity. 
