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so I've made a start....
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Michael Offline
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Post: #21
RE: so I've made a start....
Can't see your pics, gordo. Squonker sounds like a great idea, I'm interested to see how you'll make it all fit in the box what with that giant battery pack and all. 

So, is this just a random fun project to see what kind of insane levels you can vape at, or is there a particular reason the lipo packs are better than li-ion batteries? It seems like a bit of overkill imho, but maybe there's something I'm not seeing. 
14-10-2014 06:26 PM
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gords1001 Offline
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Post: #22
RE: so I've made a start....
You wont ever hit 100watts with a single li ion cell. And to get close is over stressing the cells, compromising cell life and you get no runtime at all.

I have smaller cells that would it appears, easily do a night and fit in the palm of my hand with a ten ml bottle.

The main point to all this is to practice safer high power vaping, pushing li ion cells with .2 or lower builds isn't ideal from a safety point of view and they really do struggle. This build is drawing far less current to do far more - less stress on a cell pack capable of providing more current than any round cell available today, less stress on components, no contact arcing where kanthal badly connects to a centre post for example. I've got attys with blue centre posts from poor connections...... current generates unwanted heat in places you'd rather it didn't.

And the big thing for me is runtime between charges. Everytime you recharge a li ion or lithium polymer cell it degrades. If you recharge them more than once a day, you wont get a year out of your cells.

There are now 2s li ion box mods hitting the market. There are no convenient balance chargers for those cells, none that your average guy will use, so we have mods pulling high current from unbalanced cells that can get mixed up.

Its only a matter of time before a charged cell is fitted with an uncharged cell and a reverse charging situation happens, thats impossible with a lipo pack charged on a balance charger it'll throw up fault codes as it analyses each cell.

Also.... photobucket or the forum software is being stupid. Hence no picture. Ill try again later
(This post was last modified: 14-10-2014 07:26 PM by gords1001.)
14-10-2014 07:25 PM
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Michael Offline
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Post: #23
RE: so I've made a start....
Thanks for the explanation mate. I got myself a dual 18650 box mod that can push up to 100W, but I've found that 100W is just way too much for me even with a cloud chasing build, so I keep it around 65-70W (69W just for fun lol). I've heard that I have to be very careful with my cells to make sure they're equally charged and never used separately, so it makes sense that a lipo pack like that would be inherently safer since it's all one piece. 

Is it relatively safe to use lower sub ohm coils (like .16ohm - .20ohm) with two 18650s in series? Or should I build myself a lipo pack mod like yours? Wink
14-10-2014 08:02 PM
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Don Offline
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Post: #24
RE: so I've made a start....
It isn't safe. At 8.4V and 0.2 ohms you are running up to 42A. This is not safe with ANY 18650. When you double the voltage, you double the resistance to keep the power constant.

Straight Ohm's Law

v= IR
Or I (current) = V/R volts/resistance

TVF tested battery info to be found here

[Image: 24291313393_16615b20b2_m.jpg]
14-10-2014 08:09 PM
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Michael Offline
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Post: #25
RE: so I've made a start....
Where did you get the 8.4V? Since mine is a regulated mod with variable wattage, I used this watts/volts/amps/ohms calculator to find amps and voltage using the wattage and ohms. It said that at 69W and .2ohms, I'd get ~3.715 V and ~18.574 A. That seems like a pretty safe range to me, so I thought I was fine but I'm inclined to trust you more than my limited knowledge on this lol
14-10-2014 08:46 PM
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Don Offline
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Post: #26
RE: so I've made a start....
I assumed you were upping the voltage by using the cells in series - which would give you 8.4V. There are good reasons to do this if you want to vape at high power, not least the difficulty of reliably and accurately measuring low resistances.

Using the cells in parallel (As long as they are identical) you should be able to roughly halve the resistance. Say the cells are rated to 20A each, in parallel they should work to 40A. Let's use 84W as the sums are a bit simpler. No no real 18650 on its own can produce that, the voltage will sag. That would be 20A at 4.2V. With two cells they are being asked for 10A each. In parallel you can halve the resistance. Actually, I'd not go as far as halving it So I'd aim for say 35A from the pair (17.5A each) which in physics experiment land would be 147W. Actually, it will be less than that in any non-regulated mod as the cells' voltage will sag.

TVF tested battery info to be found here

[Image: 24291313393_16615b20b2_m.jpg]
14-10-2014 08:53 PM
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gords1001 Offline
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Post: #27
RE: so I've made a start....
I simply wouldn't stack li ion cells and vape on them. And I love stacked torches, but your getting into the cells limits and that to me is risky. Any imbalances = catastrophe. Lipo packs and chargers are so cheap now its just not worth the risks.
14-10-2014 09:08 PM
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Michael Offline
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Post: #28
RE: so I've made a start....
Ok thanks for all the info. I might look into making a lipo pack mod like yours, since I really don't want to blow my face off. I just thought that my box mod would be much safer than you're making it sound, so I wanted to figure out what's going on with it. My cells are high drain 2500mAh 3.7V 18650s, though I don't know what their amp rating is because I threw away the box and they don't say on the side of the battery. I'm mostly using my Big Dripper with it, which I build at slightly more conservative levels anyway (anywhere from .4 ohms to .9 ohms, depending on my mood that day). Running at 69W, my current .4ohm build says it's getting 5.2V.
14-10-2014 10:25 PM
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Galaxyrider Offline
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Post: #29
RE: so I've made a start....
(11-10-2014 07:03 PM)gords1001 Wrote:  




It lives. Its fucking insane Smile

18sixfifty. The issue was you need a resistor between gate and source. It would fire and then just keep firing. The resistor pulls the gate back open so it stops and starts on the switch. Smile
Holy Smokes bro.. is that a box mod.. or a flame thrower?? LOL

Onward.. through the Fog!
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07-11-2014 01:18 AM
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