Mod with Safety issues???

[Rocketman]

Count your safety features like you count money.

One dollar,
one dollar and 25 cents,
one dollar and 30 cents,
one dollar and 31 cents.

 

[TBinAZ]

Think about it. If a battery let loose in a tank like the ProVari, the only harm would be that you would turn into Rocketman II. Not a big deal for me, and may prove to be pretty kewl.

Yeah, Something aint right.

Seeing that my Provari has ONE 1/8" hole in the end cap.

 

[zoiDman]

Think about it. If a battery let loose in a tank like the ProVari, the only harm would be that you would turn into Rocketman II. Not a big deal for me, and may prove to be pretty kewl.

Yeah, Nothing better than a APV Bottle Rocket? LOL

I say Drill a Hole in the End Cap and a Hole Above the battery, throw a 10 cent Fues in it and call it a day.

 

[spaky]

My how things have changed.

http://www.e-cigarette-forum.com/forum/modding-forum/76086-exploding-mods-discussion.html
http://www.e-cigarette-forum.com/forum/forum-how-tos/76247-exploding-mods-feedback-thread.html
http://www.e-cigarette-forum.com/fo...te-exploding-mods-real-current-situation.html

 

[Uma]

Got ya !
I don't know about metric sizes
but for 600 square mm converted to the English system:

A 1 inch hole is not big enough.
16 0.25" holes are not enough.
64 0.125" holes are not enough.
600 0.040" holes makes it with a little room to spare

Whoops, error, need more than 600 0.040" holes, my bad.
(about 740 0.040" holes)

It's easier to figure for slots.
A one inch wide, one inch long slot is close.


This metric system stuff is confusing


and I almost forgot
+1 to GV

Thanks for the sizes. If I have it drilled by someone else, I'll feel confident in knowing that it's close to right.
I might do a vent grid down one side or around the entire circum.. and then make a nice cover for it that is easy to twist around/up/down to expose the vents. I don't want the vents to collect dirt, lint, etc.. but I want it there for when needed. Think Aviss covers for the tanks or think Chameleon mods by Dancer with the matrix grid pattern, except in reverse... I might drill the mod in matrix design and then cover with solid-ish wrap... OH! Or attach a cool push up cover like the GP's button does.
Sorry to go off topic, just brainstorming a way to best safe-tify any mod I may choose to have in my stable.

 

[Rocketman]

I was being just a little sarcastic with the number of holes. Roly's slot idea gives more vent area in a hurry than a bunch of little holes. And, a 1" diameter hole would be hard to do on most PVs

Here's a thought on holes and slots though.

The cell (or cells) occupies most of the internal cross section of the PV. The top of the cell creates an 'annular orifice' that will limit gas flow from the cell and down along the side. Vent area in access of the area of this internal flow restriction may be ineffective. Once this cross sectional area has been met, downstream vents (holes or slots) do less and less. Open a lawn spigot, put a big hole in a garden hose. More holes down stream don't do much.
More space inside the PV would help but then you would need something to keep the cell centered.



(waiting for the gun barrel example now. 20,000 to 50,000 psi cartridges and vented gun barrels may not be a good analogy to a venting PV)

 

[Uma]

Sarcastic or not, it brings to light ways to go about modding a cylinder.
Picture:
SS tube with threads.
SS slotted band with threads.
GP slider button ring.
Reo Grand slider door.

I mention the Reo slider door, because it's fun playing with our sliders. We even miss that option on a tube mod. Boring tube mods anyways.
But we can mod a tube by adding our own, or by hoping a modder will invent such a device.

Or we can keep paying ridiculous prices for pipebombs with glow in the dark o-rings.
Decisions, decisions...

Sarcasm sometimes gets the creative juices flowing.

One vent slot at 1" or a band of vent slots equaling to even greater venting capacity. Covered with a slider ring that's fun to play with when we're bored and might remember to use when we're needing to. Fancy or plain, damascus steel or glow in the dark plastic, shapely or straight, ....

and it wouldn't necessarily add to the length of the mods if the steel tube cutter cut the tubes a bit shorter before threading.

 

[oldsoldier]

(waiting for the gun barrel example now. 20,000 to 50,000 psi cartridges and vented gun barrels may not be a good analogy to a venting PV)

Its been done. Barrels are ported to reduce recoil forces in a process called magnaporting. Gas operated weapons are also ported to bleed off some of the gas to cycle the operating piston/rod. And lets not forget porting barrels as part of building integral suppressors.(this last example is probably closest in scope)

 

[Rocketman]

Cylinder/barrel gap looks more like vents up at the top of a PV, integral suppressor slots are at the end on the gas path. Most of the energy has been expended by the time the pressure pulse gets to the vents (or gas port). I guess you get a few hundred fps from gas expansion past the gas port.

In a firearm, the pressure pulse travels. I think a PV failure is more like a blown breech plug on a black powder rifle.

It the gas path in the PV that might determine how much venting and where is needed.
The top of the cell inside the mod is like a sharply necked down cartridge right there where the carto connector is.

What would be a good way to improve this internal restriction? I was just commenting that impulse pressure systems (like a firearm) may not react the same as a venting (unless it a catastrophic cell explosion) a Li-ion cell.


Maybe I'm all wrong here. Heck there's a mod that is heavy duty aluminum, and a little vent by the switch is enough. Just a little gas comes out and you hear this muffled thump.
Say it, and others will believe it.

soldier, with your experience with um, ah rapidly expanding gas systems
should be be preparing for the 'big bang' type of cell failure, or the 'flame thrower' cell failure. (at the cell, not the PV)

 

[rolygate]

If I were going to build a tubemod now I'd look seriously at box section SS ('square tube') with a mylar inner sleeve. The vent holes could be anywhere with that arrangement and the sleeve stops the battery shorting to earth.

With luck, new designs will come along that are intrinsically safer, like this. Plus it wouldn't roll off a table...

 

[zoiDman]

I don't know if the Owner did this or if He/She meant that the OEM did is, but this was posted in another thread.

there are vent holes now!

 

[Rocketman]

Do you really think one of the revised ones has made it to the customers yet?

No comment on the modification, there will be plenty without mine

 

[Rocketman]

Roly, that sounds good. The boxes that are currently used (I've done a few) just don't look as stylish at a machine turned cylinder. Making the PV cylinder a little bigger to increase the gas path cross section would make an 18650 mod look like a 26650 mod. By the time you get to 32650 cells, you're looking at 1.5 inch tubing (done that too ).

4 sided or even hex shaped extruded or machined tubes would give a guaranteed flow path.
It's just so darn convenient to work with the cylinder.


It might be time to change the paradigm of having the cell positive at the top. Design an easy to fabricate PV with the cell upside down and suppressor slots at the bottom.

 

[zoiDman]

Do you really think one of the revised ones has made it to the customers yet?

No comment on the modification, there will be plenty without mine

I have No Clue.

I don't even know for sure what the Mod is in the Picture or who the OEM was.

I did noticed though that the Member who posted the Picture in the other thread was not located in the USA.

 

[oldsoldier]

@rocketman there are a lot more variables when you use the gun barrel analogy especially when you drill multiple ports for a suppressor. It is probably not the best analogy for battery failure in a PV, I think pressure relief valve analogy (like on a hot water heater) is actually more fitting since the gun barrel is designed to direct the gas and launch the projectile and is "proofed" to handle 2-3x the standard pressure generated by the intentional detonation of the gunpowder. I think the main difference here being that the gun is acting as intended and was engineered to "vent" the gas, where the PV battery is in catastrophic failure mode.

 

[Rocketman]

Guess you wouldn't want to carry a gun designed like a thin walled PV with an 18650 "cartridge"




(gate valve on a turbocharger?)

 

[markfm]

From looking at this earlier in the year:

1) As already noted, yes, even imr can vent. Sarge started an excellent thread showing a vented battery.

2) Looking at faa studies, it looks like many (all?) Of the batteries are designed to vent out the positive end. If you have a stacked battery setup that would mean perfect world has nice venting around the middle and near the top, else a well oversized tube to accommodate swelling.

3) The current 600 mm2 recommendation is iirc a really large increase in cross section compared to earlier number(s) posted. Net, people haven't had the time/$/responsibility
to come up with a testing-backed value.

Personally i cringe when i read people talk about stuffing the widest diameter batteries in that can possibly fit, and stacking on top of the tight fit, in popular widely-recommended apvs. (general observation, not talking about this particular apv)

Kudos to a vendor being responsive if they find a whoops, honest mistakes do occur.

 

[rolygate]

In response to Russ's comments on his show last night, to be honest I'm tired of discussing this issue right now. It's taken two and a half years of work - and constant abuse being received - to get to the point where most people agree with me that metal tubemods need gas vents. Two years ago there were about three people who agreed with that.

I don't think nearly enough has been done to fix the problem and, honestly, picking on one new model that is substantially the same as many others seems a waste of time to me. In my opinion it is substantially the same thing if an APV fails the balloon test or passes it but just has switch venting or a couple of small holes somewhere. Neither of those will stop it exploding if things go wrong and it's not built like a tank.

Vent holes at the bottom end are especially useless since we know very clearly now that the batteries can swell and block the tube, causing gas pressure to rise at the top of the tube and blow the top end off. Any gas pressure testing of an APV in a testing environment would involve blocking the center of the tube then injecting high pressure at the top end. Only two types of device can survive that:
- An APV with minimal venting but very strongly built - like a Silver Bullet, which has very thick wall tube and heavy threads.
- An APV with substantial gas venting at the top end.

As regards my comment on the SB, it was kind of a throwaway comment that might have been misinterpreted. We know that the SB has survived at least three battery explosions without harm to the user. My one is a bit plugged up with liquid leaks and coffee spills so maybe that's why it doesn't easily vent through the switch (it does if you blow hard enough, though). Even so it will survive a blowup most likely because they always do, apparently. I had a battery go hot in mine due to the usual shorted-out adapter. The spring collapsed and hot gas came out of the switch and also the threaded joint (both my thumb and forefinger got hot), so I knew to drop it.

I'd never stack two cells in it without drilling some vent holes though - that would be taking way too much risk. Just because an SB is known to have survived several 2-cell blowups in the past doesn't mean one won't fragment, one day. There are other models around that look far riskier: some don't seem to have any visible vents at all, so it seems to be expected they will be as strong as an SB in a twin-battery failure (and we know at least one model failed that test, which has resulted in a civil suit for damages); some are flimsy things with a vent at the bottom, which stand about as much chance of surviving two primary cells going thermal as an eggshell; and so on.

Things are certainly improving, but too slowly. It looks as if the IECSB will just buy APVs and test them to destruction, then publish the results - without waiting to be asked by the vendor. That will be interesting.

It's very true that more needs to be done in the way of consumer affairs and safety issues. The problem is a shortage of resources since the vendors won't pay for that work, they stand to lose from it. My fear is that because the funding isn't there to support consumer product safety testing, government will do it for us. They always use a sledgehammer to crack a nut.

 

[markfm]

Roly -- Is iecsb real? Maybe it's just my smartphone, but I don't see any actual content, just a couple of blank title pages for different areas. Members? Any criteria at all?

 

[hmlessalky]

While a testing group may be a great thing and exactly what is needed, I find it hard to get behind a 'board' that puts up a page without any information and hides all of the websites ownership and contact information behind a blocker (whoisguard).

Just sayin'....

Salky