E-cigarettes, high wattage/current drain, and Li-ion cells

[xwarp]

So I've been using an electronic cigarette to cut down on my smoking. It's helped quite a bit and I am enjoying it.

Having gotten into it, I do as many others do with just about anything else, and that is get on the net and start the research.

What I've found, is that a lot of people that have no clue about electronics are all of a sudden self proclaimed ee's because they learned ohm's law......

In any case, the actual subject matter of this thread is:

When 2 Li-ion cells are used in a device, it's recommended that they are "married", meaning they should be charged and used together for the life of the cells. This is mainly for safety of the user, device and cells.

Makes sense.

What doesn't make sense to me:

When these two married cells are charged, it is recommended that the cells position in the load are switched after every charge cycle.

As far I know, all these devices in particular that use two cells, the cells are either used in series, or parallel, in which case, I believe that if there is an internal defect in one cell, it won't matter which position it is in, in the device.

Please educate me further.

[amyk]

From the standpoint of balance it doesn't make sense, since cells in laptop packs most certainly aren't "rotated" and they work just fine... but perhaps it's about cleaning the contacts of both cells so they wear evenly? These "vapes" do draw very high currents...

[dexters_lab]

there is a lot of crap surrounding these things, my fiancée has just upgraded to a new 'sub ohm' vaporizer... which runs upto 50watts.

There is a lot of marketing about them just to try and differentiate one product over another, or those that sell these products invent crap that their customers believe, to re-enforce their perceived authority on the subject

When 2 Li-ion cells are used in a device, it's recommended that they are "married", meaning they should be charged and used together for the life of the cells. This is mainly for safety of the user, device and cells.

Makes sense.

What doesn't make sense to me:

When these two married cells are charged, it is recommended that the cells position in the load are switched after every charge cycle.

As far I know, all these devices in particular that use two cells, the cells are either used in series, or parallel, in which case, I believe that if there is an internal defect in one cell, it won't matter which position it is in, in the device.

yea, cant see any reason why it would make any difference

[zapta]

yea, cant see any reason why it would make any difference

If the balancer has an offset between the sensing of cell 1 and cell 2 then the rotation will theoretically even the charge pattern of the two cells.

I would worry more though about the chemicals I inhale than the health of the battery cells.

[xwarp]

yea, cant see any reason why it would make any difference

If the balancer has an offset between the sensing of cell 1 and cell 2 then the rotation will theoretically even the charge pattern of the two cells.

I would worry more though about the chemicals I inhale than the health of the battery cells.

That is something I don't know, specifically with the unit I have, as to whether or not is has some sort of balancing circuitry.

I highly doubt it.

I'd believe that the majority of the units, the cells are used either parallel or series, with no regard to monitoring the voltage differences between the individual cells.

[zapta]

[you are not cutting anything.

The anti smoking activists have hard time adapting to this disrupting curve ball.

[Alex Eisenhut]

So I've been using an electronic cigarette to cut down on my smoking. It's helped quite a bit and I am enjoying it.

Having gotten into it, I do as many others do with just about anything else, and that is get on the net and start the research.

What I've found, is that a lot of people that have no clue about electronics are all of a sudden self proclaimed ee's because they learned ohm's law......

In any case, the actual subject matter of this thread is:

When 2 Li-ion cells are used in a device, it's recommended that they are "married", meaning they should be charged and used together for the life of the cells. This is mainly for safety of the user, device and cells.

Makes sense.

What doesn't make sense to me:

When these two married cells are charged, it is recommended that the cells position in the load are switched after every charge cycle.

As far I know, all these devices in particular that use two cells, the cells are either used in series, or parallel, in which case, I believe that if there is an internal defect in one cell, it won't matter which position it is in, in the device.

Please educate me further.

If any cell rotation would be required, the RC guys like me with their 3S and more packs discharging 200 amps would be in a world of trouble.

[Ian.M]

Thermal aging issues?  The cell nearest to the heating element probably gets quite a bit warmer than the other one.

[xwarp]

...been using an electronic cigarette to cut down on my smoking....
...2 Li-ion cells are used in a device...

you are not cutting anything.

Not sure what you are referring to when you say "you are not cutting anything".

Care to clarify?

[Len]

you are not cutting anything.

Sure he is. He's cutting down on carcinogenic combustion products while getting a bigger dose of the drug he's addicted to.

[xwarp]

you are not cutting anything.

Sure he is. He's cutting down on carcinogenic combustion products while getting a bigger dose of the drug he's addicted to.

I was hoping to avoid having this thread turn into THAT debate because it's not relevant to the content of this board.

That said, I'll say this, unless he's a doctor with factual proof that supports that drive-by quality reply, then it's worthless.

After 3 weeks of using the e-cig, my breathing, sense of smell and taste have gotten better....a LOT better.

Oh, and, the amount of nicotine has dropped. I still occasionally light up a cigarette, but I can tell the difference when I get about half the cigarette down.

[SeanB]

Nicotine, a powerful addictive drug. Cigarette, a device that converts plant material containing a small amount of nicotine into a form it can readily be absorbed by the epithelial lining of the lungs, along with a lot of other incomplete combustion byproducts. Ecig, a device to deliver nicotine to the lungs with good efficiency. Nicotine patch, a device that delivers a low dose of this addictive drug via the skin, using a somewhat inert carrier molecule.

One is frowned on as noxious, the other is frowned on as being a poser and the last is totally invisible. Your choice.

[ConKbot]

If the lead lengths aren't balanced in a parallel box. I.e. 10mm from the battery to the junction on one cell, 20mm for the other, then the high rate discharge won't be equal. Obviously it won't matter for a series box as the current is always equal. But the battery situation for ecigs is already sketchy at best, so I would let the general non technical public keep it up with cycling cell locations.

I've seen some unregulated boxes with low voltage cut offs and some with overcurrent shut offs too, but the majority of the ones that have none are accidents waiting to happen, imo. High rate lithium cells are great, but nothing to be lax around, and "general public" handing bare cells and using them with no protection is mildly worrying.  Especially when cheap regulated, variable wattage units are available.

[Fungus]

...been using an electronic cigarette to cut down on my smoking....
...2 Li-ion cells are used in a device...

you are not cutting anything.

Sure he is. The inside of his mouth/throat/lungs/nose will no longer be coated with tar and ash.

To answer the question: There's no electronics reason to swap batteries - components in series work exactly the same no matter which order you connect them.

The only possible reason is external factors, eg. Is one of them right next to the heating element? Does it get hot in use?

Pull them out right after you take a big hit of nicotine and see...

[Psi]

What doesn't make sense to me:

When these two married cells are charged, it is recommended that the cells position in the load are switched after every charge cycle.

As far I know, all these devices in particular that use two cells, the cells are either used in series, or parallel, in which case, I believe that if there is an internal defect in one cell, it won't matter which position it is in, in the device.

Please educate me further.

Some e-cigs have a mcu/digital-logic that is used to flash the LED and "lock" the device so it can't be accidentally turned on in your pocket.

I can see some dodgy e-cigs designer saving money by removing the 5V reg and running the mcu across cell 1 while running the heater across both cells in series.

In that situation it would make sense to swap the cells around so one doesn't always discharge more than the other.

But that's really the only reason i can think of for having a warning to physically swap cells around.

[justanothercanuck]

I could be wrong, but it's not the heat of the attached atomizer that they recommend swapping the batteries in your series set, but rather that one battery sees more usage than the other, and that can cause premature aging of one battery over the other.  If one battery goes bad before the other one, and you don't catch it, there is a possibility of venting.

However, venting on an IMR isn't that bad really.  The battery gets hot, some fizzing happens and the electrolyte leaks out.  I've heard that ICR's are more dangerous though (as in "explode"+fire), which is why people pushed a few years back to stop using them for vaping.

Honestly though, if you need more than ~20 watts, you're probably not vaping for the nicotine, but rather for clouds.

Also, don't let the trolls get you down.  You're doing what you want to do and feel is right, so screw them. 

I can see some dodgy e-cigs designer saving money by removing the 5V reg and running the mcu across cell 1 while running the heater across both cells in series.

I don't think I've ever seen a device that does that.  Tube-shaped devices only have 2 connection points, and unevenly discharging the batteries in this fashion in a box-shaped device would unbalance the batteries.

[Zero999]

you are not cutting anything.

Sure he is. He's cutting down on carcinogenic combustion products while getting a bigger dose of the drug he's addicted to.

Most studies carried out on nicotine are complicated by the fact they were on smokers.

I'm not a doctor but what I've read, I believe nicotine in itself is nowhere near as harmful as alcohol and is not much more harmful than caffeine.

[Psi]

I'm not a doctor but what I've read, I believe nicotine in itself is nowhere near as harmful as alcohol and is not much more harmful than caffeine.

Its definitely an order of magnitude (or two) more addictive than caffeine.

[Fungus]

I'm not a doctor but what I've read, I believe nicotine in itself is nowhere near as harmful as alcohol and is not much more harmful than caffeine.

Its definitely an order of magnitude (or two) more addictive than caffeine.

addictive isn't necessarily the same as harm

(except maybe to your wallet)

[Ian.M]

Caffeine LD50  150 - 200 mg/Kg.
Nicotine LD50   6.5 – 13 mg/kg.

A typical cup of coffee contains roughly 80 - 175 mg of caffeine and the inhaled smoke from a typical cigarette contains roughly 1 - 3 mg of nicotine.   
Draw your own conclusions on the risks of overdose.

[xwarp]

We can just agree to disagree because your assumptions are far from correct.

my friend next got fancy setups 2 batts and whatnot he spent thousands on that, nuts.

Yeah, it's pretty nuts to believe anyone paid thousands for all that. I'm sure he did. 

i see you are following his path.

No, I am certainly not and again, your assumption is incorrect, but, even if I had, what do you care? You did not work for the money I have, and you can't know what I've spent on this stuff.

you are not cutting anything.

You have no idea.

Please don't bother posting in this thread again. Your responses aren't appreciated.

[ConKbot]

i never saw an advice to dismantle and swap a 3 or 4 cells lipo/lion now and then so i guess its irrelevant. otoh i'm thinking of making pwm circuit so we can vape by a normal copper wire easily available and ultra cheap compared to that kanthal crap.

Why the hate for kanthal? As far as heater materials go, it's not that bad. Holds its shape even under red heat, protective coating of aluminum oxide forms on it quickly, hence being able to do tight wraps without shorts. I believe temp control units run in the 400 to 500f range, and I'd expect copper to degrade pretty quickly around there, and probably change the taste a lot.  Not saying it won't work, but I'd expect some complications.