Ok. This actually happened

I agree with what you say regarding the likelyhood of batteries touching when the damage is somewhere in the middle. If insulation is missing at the base like in the photo, it's very possible that it could touch the mod housing with a jolt. If that battery is not the first in the series (i.e. at the same potential as the housing), it would cause a short quite easily.
Batteries were missing missing pieces on base and top. I did say I only took the three pics. I just wanted to show what happens when you don't follow advice and common sense.
 
The battery shorting against the mod casing makes sense to me. Even if two batteries had holes in the wraps at the corresponding point, I'm still struggling to see how metal touches metal. If we magnify the contact point under a microscope, I imagine it would look something like this:

View attachment 95953

Where black = metal battery casing and red = wrap. So even if you have a hole at the corresponding spot in both wraps, you still have the thickness of the wraps keeping the two metal surfaces apart. The gap might only be a few microns but it's nevertheless still a gap. Unless the potential difference is sufficient to induce a spark between the two surfaces? I can't see it at these voltages, though.

You could touch metal to metal by holding the two batteries at right-angles to each other and pressing them together. But side by side as they would be in a mod, I don't see how contact is possible unless you clamped then together in a vise or somesuch.

I'd really like to understand more about the actual physical/electrical processes involved in battery shorting and venting. I tend to follow a safety-first "if a wrap is torn or even nicked then re-wrap" approach. But I'm doing it because "it says so in the Bible", not because I can understand the actual science.

The rewrap immediately when torn is the best and safest approach. To a degree you are right that torn batteries themselves, especially as depicted above, should not be able to cause a short unless rotated. Maybe not battery to battery directly in this case.

In any mod, you cannot guarantee that the batteries are always aligned 100% parallel to each other in the mod, as the slots they fit in do have some play in them. In this case, I think the real culprit is the one with the torn base that was likely rotated towards the exterior of the metal battery casing.
If the casing of the mod is typically at negative / ground potential due to the 510 base being part of the casing, the batteries themselves do not need to touch each other. They simply need to touch the casing or common ground.
Even if the plate is not always touching the mod casing, when it's held and pressure is applied while firing, it can easily touch due to the looser magnetic bonding that allows slight movement as opposed to fixed pins and matching holes that do not allow sliding about.

Even though they are used in series, there are individual connections between EACH of the battery negative and positive terminals to charge each battery separately via an individual charge circuit, and to monitor their voltages individually. A faulty charge circuit in the mod could also cause a short between any of the two batteries.
Not all electronics go open-circuit when they fail. Some of them actually short out (think molten metal) before they and their neighbours go bang.

Never underestimate Murphy's Law: If anything can go wrong, it will.

EDITS : typo & perpendicular != parallel
 
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Believe me. I know.
Luckily when I started vaping, the big boys here in PE showed me the ropes. I listened to their advice and learnt from them and common sense and from the internet when reviewers were actually teaching and not selling.
The help is out there. There's no excuse
As we know,9 times out of 10 it's user error.
 
My unqualified guess, the torn wraps are just indicative of poor safety practice in general from this person, unbalanced charging and non-rotation of batteries (also since they are browns, maybe they are dodgy) lead to some kind of excessive drain on one and then the rest. Looks like slot two was the main culprit here as the burn is on top.

*edit This mod has also most likely been dropped pretty hard at some point notice the huge chip near the positive terminal in slot 1? Just a general cluster **** waiting to happen.

Non rotation of batteries?
I've only recently moved to a 2 cell mod, should I be changing the slots I put the batteries in?
I put them in the charger at night and reinsert in the same slot in the mod every morning
 
Non rotation of batteries?
I've only recently moved to a 2 cell mod, should I be changing the slots I put the batteries in?
I put them in the charger at night and reinsert in the same slot in the mod every morning

Yes, it's just good practice, because in a series circuit the first battery gets hit more than the second/third etc.
 
Ok, @Feliks Karp , I'll byte, please to be explaining, how, in a series circuit, the 1st battery gets hit more than the others, assuming there's more than one... this aught to be good, where's my popcorn...

Well it appears by your smart-arse remark you know better; so instead of a patronizing quip why do you not offer a more informed reply educating myself and others on this site? Are you just another arrogant fish in an already overwhelmingly full pond, or are you wanting to be part of the solution?
 
@Kalahari stoommasjien lets use the chalk and puppets:

Consider a snow-sled, horsed by 6 huskeys running in 2 x 3. Will all huskeys exert the same amount "work/effort" to pull the sled?
 
Ok, @Feliks Karp , I'll byte, please to be explaining, how, in a series circuit, the 1st battery gets hit more than the others, assuming there's more than one... this aught to be good, where's my popcorn...

Well it appears by your smart-arse remark you know better; so instead of a patronizing quip why do you not offer a more informed reply educating myself and others on this site? Are you just another arrogant fish in an already overwhelmingly full pond, or are you wanting to be part of the solution?

Play nicely :)
 
And to answer your question, no there is probably no real electronic reason why the positioning will effect the drain rate, maybe it's just the crappy volt meters in most of these mods (which also ends up effecting the balance of charge when using the crappy USB charge ports), but most of them read the uneven volt ranges in order. A multi-cell circuit will always have some kind of drain discrepancy (even in parallel), because of minor manufacturing differences as well as various physics at play in the circuit. This would also apply to our chargers. So it simply becomes good practice to rotate cells to be fully sure that they are all getting a relatively even amount of wear and tear, and lifespan.
 
Play nicely :)


Play nicely how exactly? He quite literally gave a smart-arse quip without any intrinsic value to a conversation. I was quite literally stating the truth. This crap comes up more and more on this site, we have a membership comprised of people from all fields including engineering, electronics, and education, yet most of them shoot out sarcastic and patronizing comments in response to statements that may be misinformed instead of actually adding value to the community as a whole. Why not take your knowledge and help build this community?
 
@Cespian not sure what you're getting at, but Huskeys etc. don't make an apt analogy, that would only work if the Huskey's ran on a circular track where the Huskeys only could move the snow-sled if everything worked together properly, the front Huskeys would need to be tied to the back of the snow-sled etc., actually since you want a 2 X 3 scenario it could work lopsided... but hey, again, a kak analogy.
As for @Feliks Karp, you should know by now, being the vaper that you are and presumably also having messed around with a mechanical mod, then again, maybe not, that never mind where in your series circuit you measure the current flow, it amazingly is the same everywhere, which pretty much implies that both batteries are being asked to provide the same amount of current at their respective voltage. Now it could be that the batteries don't have an equal voltage, that they inherently are imbalanced from the start (one batterie is a 1.8Ah and the other a 2.5Ah capacity cell, lets say) in which case, eventually the circuit would stop operating because one battery is drained where the second one has some energy left. But in a series circuit both batteries effectively would be asked to provide the same amount of power.
 
Play nicely how exactly? He quite literally gave a smart-arse quip without any intrinsic value to a conversation. I was quite literally stating the truth. This crap comes up more and more on this site, we have a membership comprised of people from all fields including engineering, electronics, and education, yet most of them shoot out sarcastic and patronizing comments in response to statements that may be misinformed instead of actually adding value to the community as a whole. Why not take your knowledge and help build this community?

Self control :) Rate the post and move on
 
Self control :) Rate the post and move on

So instead of creating and engaging conversation and through that content for the community, I should passive-aggresively use a rating further adding zero value to the forum? Sorry no, I'd prefer to actually stir up a mild controversy and have an interaction that maybe leads to something being created rather than clicking a button and having nothing beneficial maybe pop up at the end of the day.
 
So instead of creating and engaging conversation and through that content for the community, I should passive-aggresively use a rating further adding zero value to the forum? Sorry no, I'd prefer to actually stir up a mild controversy and have an interaction that maybe leads to something being created rather than clicking a button and having nothing beneficial maybe pop up at the end of the day.
Never said you can't state an opinion but let the OP make up his own mind which version of info to use.

So far on the forum all I see is guys fighting over their opinions and then the thread get locked. A waste of energy if the discussion does not go anywhere?
 
@Cespian not sure what you're getting at, but Huskeys etc. don't make an apt analogy, that would only work if the Huskey's ran on a circular track where the Huskeys only could move the snow-sled if everything worked together properly, the front Huskeys would need to be tied to the back of the snow-sled etc., actually since you want a 2 X 3 scenario it could work lopsided... but hey, again, a kak analogy.
As for @Feliks Karp, you should know by now, being the vaper that you are and presumably also having messed around with a mechanical mod, then again, maybe not, that never mind where in your series circuit you measure the current flow, it amazingly is the same everywhere, which pretty much implies that both batteries are being asked to provide the same amount of current at their respective voltage. Now it could be that the batteries don't have an equal voltage, that they inherently are imbalanced from the start (one batterie is a 1.8Ah and the other a 2.5Ah capacity cell, lets say) in which case, eventually the circuit would stop operating because one battery is drained where the second one has some energy left. But in a series circuit both batteries effectively would be asked to provide the same amount of power.

Ok mr. Smart-Ass. My analogy is about the tolerance/strength/endurance of each huskey. Same with batteries, the chemistry of batteries differ, and depending on the circuit, resistance on components (even contact plates) does affect drain/work/effort of each battery/dog. Even though minute, its a thing. I dont have the energy to argue man, I had a cold shower this morning and its apparent that you came here to troll. Peace out. Let a VALUABLE discussion continue.
 
why the cold shower?

Geysers Thermostat busted during the night :( so water was pissing from the overflow (or Im assuming its the thermostat lol). Had to shut it off immediately. Managed to save alot of the water in a bin at least so its not all wasted, the banana tree is begging for water.
 
Geysers Thermostat busted during the night :( so water was pissing from the overflow (or Im assuming its the thermostat lol). Had to shut it off immediately. Managed to save alot of the water in a bin at least so its not all wasted, the banana tree is begging for water.
That sucks :( I can't function without a hot shower in the morning :(
 
Ok mr. Smart-Ass. My analogy is about the tolerance/strength/endurance of each huskey. Same with batteries, the chemistry of batteries differ, and depending on the circuit, resistance on components (even contact plates) does affect drain/work/effort of each battery/dog. Even though minute, its a thing. I dont have the energy to argue man, I had a cold shower this morning and its apparent that you came here to troll. Peace out. Let a VALUABLE discussion continue.
We'll let's see, I'll shoot 5 of your Huskies, the 6th one has enough strength and endurance to drag 5 dead Huskies and a snow-sled around, that sounds feasible, now lets replace the Huskies in your scenario with 6 X 18650 Cells since its a parallel and series circuit combined, the analogy to the original scenario is already knackered, now if I take 5 cells and make them open circuit (kill the Huskies) the single remaining cell would not, never mind how much power it has available let the current continue to flow... so, Mr even Smarter-Ass, your analogy tripped over itself and had a cold shower, it seems...
 
We'll let's see, I'll shoot 5 of your Huskies, the 6th one has enough strength and endurance to drag 5 dead Huskies and a snow-sled around, that sounds feasible, now lets replace the Huskies in your scenario with 6 X 18650 Cells since its a parallel and series circuit combined, the analogy to the original scenario is already knackered, now if I take 5 cells and make them open circuit (kill the Huskies) the single remaining cell would not, never mind how much power it has available let the current continue to flow... so, Mr even Smarter-Ass, your analogy tripped over itself and had a cold shower, it seems...

borat-thumbs-up.jpg
 
So other than using Google, reddit and huskie-logic (seriously, huskies?), can we ask an electrical engineer?
Yes, we can.
I've sent this question off to our inhouse elec.eng. to see what he says.
I have no bloody clue why people choose to stir and fight over every little thing sometimes. Will report back when I have an answer to the original question.
 
<SNIP> the chemistry of batteries differ, and depending on the circuit, resistance on components (even contact plates) does affect drain/work/effort of each battery <SNIP>
This has some merit, but none of this would imply, that in a series circuit the cell that is 1st, (what does that actually even mean? the one closest to the positive side of the circuit? that would be the last, since convention states that electrons do the moving, thus that would be the last cell, the 1st one would be the one whose negative end is connected to the circuit, surely) does any more work gets "hit harder" than any of the other cells in the circuit.
As for cells differing, certainly 100% true, remember having 2 cells standing upright next to each other and you bumped the one, accidentally and it fell over, now the two cells, which maybe were pretty identical to start off with, are less identical, because the one cell got a shock, it fell over and I'd imagine has a slightly reduced capacity.
Since a lot of people run *POWER*, 80W is not unheard of and we're talking about predominantly 2 cell mods, lets call it around 8Volt for a pair of freshly charged 18650's in series and with the aforementioned 80W, we'd be looking at 10Amperes current flow. Then a fairly negligible under most conditions extra 0.2Ohm series resistance will have an impact, but it won't "hit" the one cell harder than the next, since we were talking about a series circuit. Now if we were talking about a parallel circuit, from a battery perspective then things look a whole lot different, since the contacts and wiring going to one cell, could significantly add to the resistance that this cell may be seeing compared to its neighbour. There, rotating cells does make a whole lot of sense.
 
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