Concerning venting in mechanical mods.

[Completely Average]

If you are depending on your vent holes for protection, you are doing it wrong.

That's like saying if you're depending on your seat belts and air bags for protection you're driving wrong.

Sometimes batteries fail without any fault of the user. It happens. Vent holes are the ONLY protection you have if it does, and if your mod doesn't vent well enough it can turn into a pipe bomb.

 

[IMFire3605]

Atty positive center pin/negative atty well/base/510 threading| 510 connection positive center/negative 510 threading | mod Top Cap (negative) | mod body (negative) | battery (top post positive)/battery body and bottom (negative) | mod switch (negative)

In this configuration (sorry best way I can break down the diagram or path) if the insulating sheathing is torn anywhere, being negative, it touches any part of the mod, equals an auto firing hard short no matter if the switch is engaged or not, the battery is grounded to the mod

Atty center pin (negative)/atty well/base/510 threading (positive) | 510 connection center pin (negative)/510 threading (positive) | Mod Top Cap (positive) | mod body (positive) | battery top and body (negative)/ battery bottom post (positive) | mod switch (positive)

In this configuration if the insulating sheathing is torn anywhere, being the mod body is positive, it touches any part of the mod body, only time power can flow is from this sheathing break when the mod switch is engaged unless the sheathing at the top where the positive is, will ever cause any firing if in contact with the switch pin, the switch is the circuit breaker.

O/T
but that is how I see the flow of the two configurations, a mech mod doesn't care which direction the power flows, it just conducts it, the CDR, watts, voltage, and resistance stay constant, the battery position and flow of power are just different, in a thermal runaway venting with a bottom venting mod, top venting battery, if the battery vent is pointed at the mod vent, no blocking of the gasses is present, reducing damage to the mod, might seriously burn your finger if the escaping jet is hot and forceful enough, if there is going to be shrapnel, most likely will be the switch being ejected as a projectile, but no shrapnel from the rest of the mod unless the bottom venting is inadequate to start with.

 

[WharfRat1976]

That's like saying if you're depending on your seat belts and air bags for protection you're driving wrong.

Sometimes batteries fail without any fault of the user. It happens. Vent holes are the ONLY protection you have if it does, and if your mod doesn't vent well enough it can turn into a pipe bomb.

If your battery vents I don't care if you have 10, 3.5mm vent holes. My point was, it should never get to that point.

 

[Baditude]

In my mind, vent holes in the bottom of a tube mod are in all likelihood near completely useless. Batteries vent at the positive pole. The first thing that is going to happen as the battery heats up, is the shrinkwrap contracting and tearing. If that doesn't block the gasses, then any swelling of the battery case will.

I have no idea who came up with this flawed design and why seemingly every single mod maker out there is building on this principle.

I have a lot of issues with the way most mech mods are being designed. I'm not a fan of bottom fire switches, and most mechs use this design only because they are cheaper/easier to manufacture than side fire buttons. Side fire buttons are more natural and safer.

I would guess that very few mech mod manufacturers actually test how well their devices would react during a battery venting. As someone pointed out earlier, batteries are designed to vent from their positive end (top). So why have the vent holes drilled into the bottom? They should be near the top of the mod where the gas is going to accumulate.

Why not incorporate a "hot spring" into the battery compartment? This spring is designed to melt or collapse when the battery becomes hot, and would break the electric circuit to the atomizer.

Side fire buttons could be designed to pop off to release accumulating gas. The AltSmoke Silver Bullet uses all of these designs.

IMR battery venting from top

"Ultra low resistance coils August 2014: We have now had the first confirmed mechmod explosion due to sub-ohming, which took place at the recent VapeBlast event. The device exploded, blew a hole in the ceiling 20 feet above, brought down a ceiling tile, and burnt a hole in the floor. As this was witnessed by dozens of people (also, the explosion was heard by a hundred people or so) and the photos are widely available, it is impossible to deny that it occurred. It seems lucky that no one was hurt; indeed the mechmod owner ran away in order that if any injury occurred he wouldn't be held accountable and to avoid paying for the damage. As the device became hot he threw it down, then it exploded. The incident occurred at a Cloud Contest although it is not known if the vaper who caused the explosion was a bystander or a competitor; since he was clearly stressing-out his rig it seems possible he was about to compete.

What can be learned from this
An incident like this is caused by a chain of design errors, user actions, and possibly a battery fault.

- Sealed metal tubes will probably explode if a battery vents violently
- Small vents at the bottom of the tube are useless, only very large gas vents near the top have a good chance of preventing an explosion
- Building coils lower than 0.2 ohm will raise the amp draw exponentially and this increases risk - the power graph shows a significant change at 0.2 ohms and starts to climb vertically as resistance is reduced further
- Using cheap batteries with ultra low res coils is a certain route to high risk - it needs 30 amp batteries of guaranteed high quality
- Using a 26650 cell is intrinsically safer as it can take a higher load
- Using long draws or machine-gun draws to create monster clouds stresses the battery much more
- Cloud Contests are events where people put ultra high stress on their rig to create monster clouds; if spectating, you could consider standing at the back of the room to stay safe
- If you run a Cloud Contest then you should probably check that your personal and business insurance is really, really good and is appropriate for dangerous sports
- People are now discussing the safety (!) involved with putting 100-amp pulses on their batteries in order to create the biggest clouds with the lowest resistance coils; there is only one way this is going to go and you don't want to be within the explosion radius: someone may have a counterfeit battery, or one that is just too small for this extreme usage mode together with ignoring the device getting warm or even hot."

-- Rolygate, ECF forum administrator and battery expert

 

[ReigntheGamer]

Asking questions, wants to be safe, you're well on your way to being a responsible mech vaper. Just keep doing what you're doing and it'll be a great vaping experience.

 

[XRaptureX]

Asking questions, wants to be safe, you're well on your way to being a responsible mech vaper. Just keep doing what you're doing and it'll be a great vaping experience.

I appreciate that sir. Accidents like the one posted above are only going to bring unwanted attention to the vaping community. We have enough crap to put up with as it is. I for one don't want to give the powers that be any additional reason to regulate my hobby, and it has become a hobby. This website has been a serious boon, and it would be nice if more people took advantage of it.

End of line.

 

[Completely Average]

If your battery vents I don't care if you have 10, 3.5mm vent holes. My point was, it should never get to that point.

Shouldn't and won't are two entirely different things.

Manufacturing defects shouldn't happen, but they do. You obviously believe that all batteries are 100% defect free and it's impossible for one to fail on it's own.