Vent hole in bottom cap: false sense of security?

[yo han]

With every review I see people mentioning the importance of a vent hole in the bottom cap but has this been proven to actually work?
The vent holes on the battery itself are always located at the top, opposite to the bottom cap. Now when someting goes wrong, a Li-ion will always swell up, thus getting completely stuck in the tube and making it impossible for the gasses to pass down along the battery to the bottom side of the tube. My guess is it would still blow off the top of the PV. Wouldn't it be much better to have 1 or more vent holes at the top of the tube? This makes much more sense.
But it would be even better if manufacturers started to reverse the polarity of the devices so the top of the battery would be at the bottom of the PV.

 

[NatureBoy]

So the hot gases can blow in your face?

I think the vent holes are pointless for the same reason you pointed out. None of them have ever been tested (to the best of my knowledge), so we really don't know if side drilled holes, or holes in the bottom cap would actually make a difference.

 

[yo han]

Well, I'd rather have flames coming from the top of my device than having it explode in my face
Side holes at the top should work, there's usually more than enough room above the battery.

 

[Dominique Hoogduin]

introducing air to a lithium fire..

Im sure the hole is there to relieve pressure to prevent turning ur equipment into a small pipe bomb. But im sure it has a opposite effect in case of fire.

 

[yo han]

Im sure the hole is there to relieve pressure to prevent turning ur equipment into a small pipe bomb.

That's the idea. But its location makes me wonder if it's actually going to work, hence this topic.

 

[twizted]

I might be wrong but I believe batteries produce gases when used just as they do when being charged. With that in mind I would assume the bottom hole is for the gases to safely vent away from your face while the battery is in normal use. That way you don't end up inhaling gases and/or wind up with a mini pressurized bomb in your hand.

Sent from my Nexus 10 using Tapatalk

 

[Dominique Hoogduin]

well a faulty lithium battery will expand no matter what.. even without causing a pressure increase other then compressing the air in a closed environment. Mostly they tend to do it when undercharging or overcharging. The device connected to it will have to prevent undercharge by monitoring the voltage. Overcharging is on the charger.. but that usually doesnt happen inside the device itself making the air vent obsolete in this case.

Swelling is usually not that much of a hazard by itself.. but u cant see a battery swelling inside a device.. a rupture and lithium making contact with air is the hazard here.

Only way is to test what happens when a battery swells in such a device and if that hole actually does anything until the battery ruptures .. after that it becomes a fire hazard with air introduced into it. But i still think a swollen battery is not itself a hazard.. a rupture is imho .. Iphones and cell phones dont blow up when the battery swells.. they do when it ruptures.

 

[Ryedan]

With every review I see people mentioning the importance of a vent hole in the bottom cap but has this been proven to actually work?
The vent holes on the battery itself are always located at the top, opposite to the bottom cap. Now when someting goes wrong, a Li-ion will always swell up, thus getting completely stuck in the tube and making it impossible for the gasses to pass down along the battery to the bottom side of the tube. My guess is it would still blow off the top of the PV. Wouldn't it be much better to have 1 or more vent holes at the top of the tube? This makes much more sense.
But it would be even better if manufacturers started to reverse the polarity of the devices so the top of the battery would be at the bottom of the PV.

Do you have any links to a site that shows IMR or hybrid Li-ion batteries swell when they vent?

 

[yo han]

Did I mention IMR or hybrids?
But seriously, When using the term Li-ion I meant the most common, (and less safe) type LiCoO2

 

[Ryedan]

Did I mention IMR or hybrids?
But seriously, When using the term Li-ion I meant the most common, (and less safe) type LiCoO2

Ah, the ones that can go boom when the protection circuit fails. They are not considered safe for vaping with by most people I know. Do you use these cells in mods? eGos are ICR and they are the ones that people have the most trouble with causing fires and explosions when they are incorrectly charged.

I've always felt the industry would be better off if it made the distinction between different chemistry used. They are all Li-ion, but a lot of people think ICR when they read Li-ion.

 

[yo han]

If everyone would be using Li-Mn we probably wouldn't need to talk about vent holes in bottom caps.
I'm only using IMR these days but when you check the "batteries & chargers" section you'll see people are still using ICR too (more capacity). Not everyone's informed about the safety of batteries and every starter can buy a mod and put inside whatever's available. Hence the manufacturers should build in as much safety precautions as possible. I think it would be a good idea if they made the battery go in bottom first and having the battery's vent holes near the bottom cap of the unit.
I totally agree with you that the industry should make the difference between the different chemistries more clear.

 

[Ryedan]

If everyone would be using Li-Mn we probably wouldn't need to talk about vent holes in bottom caps.
I'm only using IMR these days but when you check the "batteries & chargers" section you'll see people are still using ICR too (more capacity). Not everyone's informed about the safety of batteries and every starter can buy a mod and put inside whatever's available. Hence the manufacturers should build in as much safety precautions as possible. I think it would be a good idea if they made the battery go in bottom first and having the battery's vent holes near the bottom cap of the unit.
I totally agree with you that the industry should make the difference between the different chemistries more clear.

I totally agree manufacturers should build in as much safety as possible.

Actually I do hit the batteries & chargers forum sometimes. I don't think there are too many people using ICRs. I know it is pointed out to them when anyone who understands notices it. For higher mAh, people sometimes go with the NCR18650B at 3400 mAh, which is hybrid not ICR and I think is safe, but not sure. The 'A' version at 3100 mAh is safe. It can actually be shorted for 45 minutes, recharged and used again. I don't recommend either of these batteries to people because of the low amp limit they have. The NCR18650PF at 2900 mAh is almost there in capacity and has a 10A safe discharge.

The issue with putting a battery in with the positive end down is that if the battery's plastic sheath is damaged and the metal battery casing (negative) comes in contact with the inside of a metal mod tube (now positive) it will hard short when the switch is activated. If the same thing happens when the positive is up, the coil will fire continuously, but there is no short. You could also have vent holes at each end of the mod like the K100 has.

Really, the best thing would be if people used safer batteries and mods had adequate venting. Having a battery explode in a mod is just not safe but it will happen sometime. We have to be careful not to make things worse though when we try to improve them.

 

[Stosh]

The K100 has vent holes on the top, bottom and in the middle, also very low voltage drop. But it doesn't have engraving so is looked down on by the mech mod enthusiasts. I like mine with the 5 volt NiMH batteries, or IMR in a pinch.

 

[Ryedan]

The K100 has vent holes on the top, bottom and in the middle, also very low voltage drop. But it doesn't have engraving so is looked down on by the mech mod enthusiasts. I like mine with the 5 volt NiMH batteries, or IMR in a pinch.

Yup, my K100 has been very good to me for almost a year. Most dependable mech mod I have, not that I have many. I could not possibly care less about engraving

I take it those NiMH batteries are the 600 or 700 mAh packs? How do you find they perform and do you consider them as safe as IMR or hybrid Li-ion? From what I'm learning about them they seem to be pretty good that way.

 

[Stosh]

Yup, the 600 - 700 mAh packs, usually found in the bargain bins...and they are safer than the IMR even. They don't have as high an energy density. If they fail, they just stop working, no venting, expansion, flame, gases, etc...

They perform very well with a 2.0-2.5Ω coil, just don't last all day.

 

[twgbonehead]

The purpose of a vent hole is to allow pressure to escape, somehow. The alternative is that you have a strong metal tube, where the only possibility of pressure release is through a drastic rupture (aka "Pipe Bomb"). Vent holes can make a dramatic failure better, but it's pretty much limited to reducing effects of the tube on what is already a disastrous event. It WILL get very hot. It WILL spew high-temperature flames and potentially dangerous fumes. A vented mod can still catch your house on fire. It's unlikely, however, to blow up like a grenade, sending shrapnel around the room. It might help limit fire damage, but that's just a side effect.

The lithium batteries are the dangerous part, and if they blow, that is scary. Vents are intended to prevent the mod from making it worse, and shouldn't be relied on to make it better.

 

[certus11]

Working or not, it helps when there's airholes because then you can see smoke coming out of it and take appropriate actions faster. Now for just a moment, imagine your battery acting up inside your mech and that your mech doesn't have airholes. The battery will then have to trasnfer enough heat to your mech before you know that you need to do something....

 

[Ryedan]

The purpose of a vent hole is to allow pressure to escape, somehow. The alternative is that you have a strong metal tube, where the only possibility of pressure release is through a drastic rupture (aka "Pipe Bomb"). Vent holes can make a dramatic failure better, but it's pretty much limited to reducing effects of the tube on what is already a disastrous event. It WILL get very hot. It WILL spew high-temperature flames and potentially dangerous fumes. A vented mod can still catch your house on fire. It's unlikely, however, to blow up like a grenade, sending shrapnel around the room. It might help limit fire damage, but that's just a side effect.

The lithium batteries are the dangerous part, and if they blow, that is scary. Vents are intended to prevent the mod from making it worse, and shouldn't be relied on to make it better.

Agree with everything you said except that lithium batteries are the dangerous part. It is ICR Lithium ion batteries that burn and blow up, IMR and hybrids don't. They get really hot and vent, but not burn or explode (burn quickly). Here is a video of Panasonic and AW IMR cells being shorted.

Having a ICR battery blow in a mod is much more dangerous than if one of these batteries fail. Gas vents are better than nothing, but in an explosion they may not help much. If safer chemistry Li-ion batteries are used, most of the risk from battery failure is taken care of.

 

[emus]

I stealth top drilled nemesis clone, bagua clone and omega clone. I added stealth bottom vent holes in some mods. Enlarged factory vent holes too.

Wish a manufacturer or professional would initiate vents in popular mods to see if any shrapnel is produced, threads fail and switch pops off, or nothing happens, etc.

I'm guessing vent holes will quickly plug w/ debris and/or be blocked by swollen batt as OP said.

Perhaps threads will fail allowing switch, top or extension rings to pop apart.

Some metals containers don't form shrapnel; they just tear and/or expand.

 

[UncleChuck]

I stealth top drilled nemesis clone, bagua clone and omega clone. I added stealth bottom vent holes in some mods. Enlarged factory vent holes too.

Wish a manufacturer or professional would initiate vents in popular mods to see if any shrapnel is produced, threads fail and switch pops off, or nothing happens, etc.

I'm guessing vent holes will quickly plug w/ debris and/or be blocked by swollen batt as OP said.

Perhaps threads will fail allowing switch, top or extension rings to pop apart.

Some metals containers don't form shrapnel; they just tear and/or expand.

That's really a great idea. It seems a bit lazy that manufacturers haven't induced battery venting in their devices to see exactly what happens, but the ecig industry doesn't seem to hold its manufacturers (Chinese or otherwise) to a very high standard, if any standard at all.

A lot of devices use seamed tubing, and if there was some sort of overpressure I'd hope the tube would just fail along the seam and vent gasses. Another thing I've hoped would provide some safey is the positive 510 insulator. Most devices have the 510 pin insulated within a plastic puck. If there was extreme heat and pressure inside the tube, I can't imagine the 510 pin would remain in place long enough to cause steel tubing to rupture.

It seems more likely the positive insulator would melt/break and gasses would shoot out the top of the device through the 510 connection. Atty's center pins are usually held within a rubber insulator as well, which hopefully would also melt and allow a path for gasses.

Personally I don't worry at all about hot gasses shooting in my face. IMRs don't just instantly blow up. They get hot, then really hot, then vent gasses. If I felt my PV getting really hot the last thing I would do is put it up to my face and take a vape, I'd toss it on the ground. I've hard shorted my fair share of IMRs and it takes more than most people thing to get them to vent.

Pressing the button on a device with a hard short isn't like pressing a detonator button. You have plenty of time to notice things are getting hot and throw the mod away from you before gasses would spray your face. Now if someone feels there mod getting really hot and continues vaping, I don't think anything could help such a person.