Exceeding battery amperage

[LewisW295]

This may be the lead balloon that gets me banned but...

1. If you are going to pick up a mech mod, you are playing with a firework. All well and good in theory but one error and bang.
2. Said firework is fine to use IF HANDLED SAFELY
3. Don't give advice on the internet that could be misinterpreted. Be clear and precise. Especially with dangerous materials.

To elaborate on point 3, anyone who has ever worked in retail or consults customers will know that looking on the internet and ignoring suppliers/common sense/instructions etc always ends badly and it is ALWAYS the suppliers fault. People are more inclined to listen to other web users of similar devices whether the advice is wrong or dangerous etc. The most common one I see is people not using respirators or masks whilst mixing adhesives and getting chemical intoxication (solvent sealers etc) and respiratory illnesses. Because the internet said they'd be fine.

 

[Tralfaz]

That's a little dramatic, but if your tube has proper ventilation, you're looking at more of a bottle rocket than a pipe bomb. I'd imagine it still wouldn't be much fun to hold, though. Also as always, respect your limits.

 

[LewisW295]

That's a little dramatic, but if your tube has proper ventilation, you're looking at more of a bottle rocket than a pipe bomb. I'd imagine it still wouldn't be much fun to hold, though. Also as always, respect your limits.

Just a tad but it gets the point across.

Though I did once read that it can effectively turn your atomizer into buckshot if the vents are inadequate.

 

[Baditude]

That's a little dramatic, but if your tube has proper ventilation, you're looking at more of a bottle rocket than a pipe bomb. I'd imagine it still wouldn't be much fun to hold, though. Also as always, respect your limits.

There are not many metal tube mechs made that have "proper ventilation". IF they have any holes at all, they're usually located in the bottom of the mod. Not so good.

Batteries are designed to vent gas from their positive pole. That's where the gas will begin to accumulate. If your vent holes are in the bottom of the mod, and if your battery is blocking that gas from getting to the bottom of the mod, it won't be able to escape. Instant pipe bomb.

That's probably why nearly all of the pics of exploded mechs have their tops blown off.

The ideal location for vent holes is in the top of the mod, where the top of the battery is located.

Above is a mech which has a single vent hole in the bottom fire button, but notice there is no room for any gas to escape past the tight quarters of the battery to that vent hole. It is essentially an enclosed metal tube and therefore has inadequate venting. The vent hole in the fire button is useless.

 

[Wysardi]

What is more likely to explode on an unregulated tube mod? A subohm coil (less than 1ohm) or a coil above 1ohm?

 

[Tralfaz]

I'm not accounting for every tube ever made. Most manufactured recently will have venting at the bottom and a positive down battery recommendation. It's never going to be completely safe but warning about explosions and calling them pipe bombs is just fear mongering.

 

[Baditude]

What is more likely to explode on an unregulated tube mod? A subohm coil (less than 1ohm) or a coil above 1ohm?

If the battery fails from a hard short, it wouldn't really matter. I had an unregulated tube mod whose battery exploded a few years ago that had a 2.0 ohm cartomizer on it. Luckily, the mod was designed to vent gas where the top of the battery was located, so the mod didn't explode, just the battery.

 

[Wysardi]

If the battery fails from a hard short, it wouldn't really matter. I had an unregulated tube mod whose battery exploded a few years ago that had a 2 ohm cartomizer on it.

Can you explain what a Hard Short is? and Cause of it?

 

[Baditude]

Can you explain what a Hard Short is? and Cause of it?

short cir·cuit

noun

1. 1.
   in a device, an electrical circuit of lower resistance than that of a normal circuit, typically resulting from the unintended contact of components and consequent accidental diversion of the current.

verb

1. 1.
   (with reference to an electrical device) malfunction or fail, or cause to do this, as a result of a short circuit across it.
   "the birds caused the electricity supply to short-circuit"

A short circuit occurs when something happens to cause the battery to expend all of its stored energy at once. This generally results in either simple venting of hot toxic gases up to a catastrophic explosion called thermal runaway. Battery Mooch has a better explanation of venting and thermal runaway in this blog:

• Li-Ion Battery Chemistries - What are the differences in their safety?

Short circuits can happen when the voltage from a battery is discharged through a low resistance wire at a discharge rate that exceeds the battery’s upper amp limit. Short circuiting a battery is very close to what a mechanical mod with a sub-ohm coil is doing, except you are trying to keep the resistance under the upper amp limit – there’s a fine line that you have to be careful of when sub-ohming.

If using sub-ohm coils in your mech, know how to use an Ohm's Law calculator to insure your battery has enough amps (CDR) to safely fire the coil resistance you use. Understand that if you run your batteries at their upper discharge limit, that this practice ages your batteries at a faster rate. Therefore, your 30 amp battery will soon become a 15 amp battery, or your 20 amp battery will become a 10 amp battery.

If a coil has a short in it (whether a drop in coil or a rebuildable), it can cause the battery to hard short. If a tiny piece of wire is somewhere where it shouldn't be it can cause a short. Pressing the fire button continuously non-stop can cause the battery to over-discharge, resulting in the battery to over-heat and destroying itself. That's why it can be dangerous to pack your device in a pocket or purse. Carrying a loose battery in a pocket or purse can cause a battery to destroy itself should it come into contact with a metalic object (coins, keys). Plastic battery cases prevent this.

 

[BrotherBob]

because the resistance can't be too low but it also has to be lower than .3 because

There is a message here:

 

[AzPlumber]

I just don't understand the rationale, "I've done it and others have done it without a problem." It's the same ridiculous rationale that drunk drivers use. Doing something unsafe without an accident does NOT make it safe for you or others.

 

[bwh79]

Can you explain what a Hard Short is? and Cause of it?

Using a mech mod with coil attached is essentially "short circuiting" the battery, already. You're just strapping a piece of wire to both battery terminals and letting it get hot. If you look at an electrical multimeter, the ohm reader settings commonly have ranges of like 200 ohms, 2000 ohms, 20,000 ohms. And here we are using half an ohm, or less. Any sane electrician would call that a "short" already. We just use the term "hard short" to mean very, very low resistance, like even more very low than what we're already doing. The cause can be anything from mishandling of the batteries to a stray piece of wire in the atomizer.

 

[Baditude]

Using a mech mod with coil attached is essentially "short circuiting" the battery, already. You're just strapping a piece of wire to both battery terminals and letting it get hot. If you look at an electrical multimeter, the ohm reader settings commonly have ranges of like 200 ohms, 2000 ohms, 20,000 ohms. And here we are using half an ohm, or less. Any sane electrician would call that a "short" already. We just use the term "hard short" to mean very, very low resistance, like even more very low than what we're already doing. The cause can be anything from mishandling of the batteries to a stray piece of wire in the atomizer.

Nice description. A short in a coil will display 0.0 ohms if measured on an ohm reader. Extremely low sub-ohm coils are not that far away from a short circuit.

1.0 ohm = 4.2 amp draw
0.9 ohm = 4.6 amp draw
0.8 ohm = 5.2 amp draw
0.7 ohms = 6 amp draw
0.6 ohms = 7 amp draw
0.5 ohms = 8.4 amp draw
0.4 ohms = 10.5 amp draw
0.3 ohms = 14.0 amp draw
0.2 ohms = 21.0 amp draw
0.15 ohms = 28 amp draw
0.1 ohms = 42.0 amp draw
0.0 ohms = dead or hard short = battery goes into thermal runaway

 

[bwh79]

Nice description. A short in a coil will display 0.0 ohms if measured on an ohm reader. Extremely low sub-ohm coils are not that far away from a short circuit.

Note that there's no such thing as a true "zero" resistance, that would involve things like infinity and divide-by-zero paradoxes. Like I said, what we're doing is essentially "shorting" the batteries already, it's just a matter of "how short is too short."

 

[bwh79]

Note that there's no such thing as a true "zero" resistance, that would involve things like infinity and divide-by-zero paradoxes. Like I said, what we're doing is essentially "shorting" the batteries already, it's just a matter of "how short is too short."

Why is that funny? I wasn't making a joke...

0.1 ohms = 42.0 amp draw
0.0 ohms = dead or hard short = battery goes into thermal runaway

0.01 omhs = 420 amp draw
0.001 ohms = 4,200 amp draw
0.0001 ohms = 42,000 amp draw
etc.
There's no such thing as zero. (I mean, there is. Zero is a very real number and also a "real" number [not all numbers are "real," but zero is]. It has a "value," and it also has value. But there's no such thing as zero resistance, outside of abstract thought.)

 

[Baditude]

Why is that funny? I wasn't making a joke...

I thought your comment of "it's just a matter of how short is too short" was funny. I get it.

When I worked in a vape shop, if a customer complained their clearomizer wasn't working one of the first things we would do would be to put it on an ohm reader. If it read "0.00" ohm, we knew the coil had a short.

 

[sonicbomb]

The key thing here for me is that there is no need to exceed the CDR of a given cell. If you need more power than one can battery safely provide, use a device with more than one battery in it, simple.
Like others in this thread have said, justifying unsafe behavior with 'nothing has happened yet' is delusional. Subtly implying that you are a cool maverick by doing so to new users even worse.

 

[Coastal Cowboy]

Good discussion on battery safety.

To the OP: You can avoid your issue by relegating that coat hanger wire 22awg Kanthal to its rightful purpose and using much thinner wire in your build.

A 0.4 to 0.5 Ohm coil using 26awg, twisted 28awg or a 26/36 Clapton wire will make beautiful music on a single cell device.

Thanks to the value of Pi in the calculation of coil surface area, the decrease in coil resistance is not worth the tradeoff in coil surface area when increasing wire diameter. There's no good reason to use wire thicker than 26awg in my experience. If 26 doesn't get you the vapor you want, increase surface area instead of increasing diameter.

Trust me. Try it.

 

[NealBJr]

ATTN Novice Mech Users: Do not build like this - Tralfaz

My intention was to illustrate that there are many vapers who build low without issue and that OP needn't feel too worried about his .191 ohm build so long as his batteries are in good condition and he keeps an eye on them.

I have to strongly agree with not BUILDING COILS past the limits of the battery for day to day use. There have been many people who have done that successfully, but accidents happen. It only takes one time of it being in your pocket for it to misfire and fire continuously, or one time of you putting it in your cupholder and have something press the button accidentally.... Just anything.

If you build below the maximum CDR of the battery, the worst that can happen is you ruin a battery via a mistake. If you build above the maximum CDR, much worse can happen. Is that extra bit of ohmage worth the risk?

True story from me... I was taking a trip with my family, and took my mech mod (caravella clone). It works great. While on vacation, I decided that was the easiest to access and vape on in the car, so I used that. I put it down in the drivers side cup holder in the door, and I carefully locked it before putting it in there. However, when we were driving around town looking for a place to have lunch, I reached down and it was blazingly hot. It got hot enough to split the shrink wrap. Luckily, I built below the CDR of the battery. Sony VTC4 and I had a .8 ohm build. The battery was ruined, but nothing else was. I'm pretty sure I locked it before putting it down there. I am guessing that driving around the city and doing lots of turns and turn arounds rolled it around to unlocked position.