coil resistance

[jerseyman32]

I have a quick question , say you have two coils one is made with 28 gauge and the other with 32 and they are both are built tocthe same resistance lets say 1.5 will the one made with 28 gauge require more watts since its thicker or not?

 

[T4T3Z0R]

no but it will take longer to heat up. watts is dependent solely on volts and resistance (ohms)
watts is equal to volts squared divided bey the resistance

 

[Ryedan]

I have a quick question , say you have two coils one is made with 28 gauge and the other with 32 and they are both are built to the same resistance lets say 1.5 will the one made with 28 gauge require more watts since its thicker or not?

The power (watts) 'sweet spot' for the 28 gauge coil will be at higher wattage than the 32 gauge coil. That's because the 28 gauge coil has more wire surface area than the 32 guage coil. It will also have more mass than the 32 gauge coil which lengthens heat up time, but will mostly be negated by the higher power level you will vape at if you vape them both at their sweet spots.

 

[jerseyman32]

Thanks ryedan

 

[jonnychadootz]

I'm very interested, would you know how amperage plays into it? I ask because I use a wall adapter to power my device (my avatar) since I mostly vape when I am siting at my desk and it provides consistent power (no charging etc) Currently the adapter is 5V - 2.5A, however I recently ordered a 5V - 4A adapter since the calculator I used (Ohm's Law Calc) said that I would need higher amps to run lower ohm coils @ 5 volts, as well as noticing that my lower ohm coils (Lower gauge wire) are taking more time than I would like for them to heat up. Much appreciated for the knowledge

BTW: Interesting initial question jerseyman32

 

[93gc40]

The 28 will take more watts/volts than naturally drawn from the battery in order to produce the same temperatures as the 32. But the 28 will have much more surface area in which to vape on and can carry more heat. The 32 will heat faster and cool faster. Do a search on Ohms Law, most of your questions will be explained.

 

[Ryedan]

I'm very interested, would you know how amperage plays into it? I ask because I use a wall adapter to power my device (my avatar) since I mostly vape when I am siting at my desk and it provides consistent power (no charging etc) Currently the adapter is 5V - 2.5A, however I recently ordered a 5V - 4A adapter since the calculator I used (Ohm's Law Calc) said that I would need higher amps to run lower ohm coils @ 5 volts, as well as noticing that my lower ohm coils (Lower gauge wire) are taking more time than they I would like for them to heat up. Much appreciated for the knowledge

You've got it jonnychadootz. You are vaping a device which puts out a reasonably constant 5V and with these it's all about the resistance and Ohm's law. You will be drawing 2.5A at 5V and 2.0 ohms and will be making 12.5 watts. If you take the resistance any lower than 2 ohms it will draw more than 2.5A from the power supply and there is a risk of it heating up and burning out. With 4A available you can take it down to 1.25 ohms and 20 watts.

As for wire gauge, the correct gauge you should use depends on the power you want to vape at. Check out the Steam Engine coil wrapping calculator. The link will take you to it with it set up for a single coil at 2.5 ohms and 32 gauge Kanthal. Look at the 'Results – how to wrap, and how it will perform' section on the right side and you'll see 10 watts entered in the 'Heat flux' spot and the resultant heat flux is 285 mW/mm² (miliwatt per square mm of coils surface area). Change the wire gauge to 33 and you'll see the heat flux go up to 404. 404 mW/mm² is OK in a dripper, but it's a bit high for clearos.

'Heat capacity' is an indicator of coil heat up time, but it works in conjunction with heat flux. I find if I get the heat flux right in typical coil builds I find I can generally ignore the heat capacity number.

With a 1.4 ohm coil you get 17.86 watts. Plug in the new watts and resistance in the coil wrapping calculator and you get a heat flux of 910 with 32 gauge wire which will immediately burn juice. Now reduce the wire gauge until the heat flux becomes what you want. 29 gauge gives 321 mW/mm² which should vape quite nicely if you liked 32 gauge at 10 watts.

 

[jonnychadootz]

I'm guessing its just because of the short amount of time that the draw occurs since I have experimented with (and used for some time) coils as low as on 0.6 ohm on the 2.5 Amp adapter just to see what the results were. In retrospect, probably shouldn't have been doing that Right now, I am using a single, 30 gauge coil (7 wraps) on a 2.4mm bit (1.6 ohm) (heat flux is 289) Like a slightly cooler vape I now know what I'm going to be doing when the 28 gauge and the 4 Amp adapter comes in. The greatest piece of info was about the heat flux. I now have a greater understanding of its importance. Good stuff and thanks again

 

[AttyPops]

You probably should have started another thread jonny...'cuz it's an interesting question and probably interesting device. (not a mod, not saying I am, just would have been good in it's own thread for discussion)

The device MAY have an amp limit. The 'old' 5V pass-throughs had limits on them (due to the MOSFET switch capabilities, and maybe short-circuit protection).
Also, the cord you use may play an important role. People don't realize that the cord has a resistance too. And also, it can heat up if it's over amped, although short bursts are better than "constant on". Same reason people get in trouble with some extension cords on high-watt uses.

It looks like you're using a DIY e-cig from a ....soldering iron? Or what?

 

[jonnychadootz]

You probably should have started another thread jonny...'cuz it's an interesting question and probably interesting device. (not a mod, not saying I am, just would have been good in it's own thread for discussion)

The device MAY have an amp limit. The 'old' 5V pass-throughs had limits on them (due to the MOSFET switch capabilities, and maybe short-circuit protection).
Also, the cord you use may play an important role. People don't realize that the cord has a resistance too. And also, it can heat up if it's over amped, although short bursts are better than "constant on". Same reason people get in trouble with some extension cords on high-watt uses.

It looks like you're using a DIY e-cig from a ....soldering iron? Or what?

Maybe I should have started another thread I feel like I'm thread jacking (sort of am and I apologize Sorry jerseyman32

I've used (4 different) USB pass-throughs and they were all terrible (nowhere near enough power) as far as I know you can only really pull 5V/somewhere around 1A from a USB slot on a PC (which just isn't a good idea) even if it's plugged into a USB adapter/wall plug it won't power anything worth it (to me anyway The crappy USB pass-throughs are part of the reason that I built the device I am using now. The adapter that I am using currently is a 5V - 2.5A adapter from an old dlink router I had. If it has an amp limit/pop point I haven't found it.... yet. I check the adapter on a fairly consistent basis to make sure it doesn't get hot (been using it for somewhere around 7 months) Wish I could take credit for the device, found it on some random you-tube search. I tried it the way it is in the video and it was useless for me the way it was powered (via USB) That's when I decided to go with the adapter that is currently being used. I've had more switches break than anything (Radioshack is

 

[AttyPops]

ALL switches (buttons) will break in a PT unless you use a power MOSFET. And then there's amp/power ratings to the MOSFET.

Basically, if it's a straight through button, with all the power going through it, it arcs a lot (full voltage/amps) inside and degrades the switch contacts fast. That's why they use a little button to drive a "bigger switch" AKA MOSFET switch. Kinda like a little control button controlling the gates on the Hoover Dam.

And yeah, we always have recommended using sufficient wall adapters or other better power supplies rather than computer ports. Why risk stressing a computer port?

Now-a-days though, with the lower ohm, or sub-ohm, or really-sub-ohm fads, I'm cautious of even talking about this stuff. Anyone attempting to DIY a PT e-cig really needs to do their homework if they want above standard watts. Power supplies can be dangerous and stressed too. You don't want to release the magic-blue-smoke. Java_AZ taught me that all electronics run on magic-blue-smoke. If you let it out, it won't work anymore...

BTW...I used to use a 5V 8 watt standard coil PT with a wall wart. But I don't bother with low ohm stuff, so I was OK with that. The buttons on those were notorious for getting e-juice in them and failing. Let them dry out and they were fine. Had a really thin USB cable though, and it probably wouldn't stand up to too many more watts.

 

[jonnychadootz]

ALL switches (buttons) will break in a PT unless you use a power MOSFET. And then there's amp/power ratings to the MOSFET.

Basically, if it's a straight through button, with all the power going through it, it arcs a lot (full voltage/amps) inside and degrades the switch contacts fast. That's why they use a little button to drive a "bigger switch" AKA MOSFET switch. Kinda like a little control button controlling the gates on the Hoover Dam.

And yeah, we always have recommended using sufficient wall adapters or other better power supplies rather than computer ports. Why risk stressing a computer port?

Now-a-days though, with the lower ohm, or sub-ohm, or really-sub-ohm fads, I'm cautious of even talking about this stuff. Anyone attempting to DIY a PT e-cig really needs to do their homework if they want above standard watts. Power supplies can be dangerous and stressed too. You don't want to release the magic-blue-smoke. Java_AZ taught me that all electronics run on magic-blue-smoke. If you let it out, it won't work anymore...

BTW...I used to use a 5V 8 watt standard coil PT with a wall wart. But I don't bother with low ohm stuff, so I was OK with that. The buttons on those were notorious for getting e-juice in them and failing. Let them dry out and they were fine. Had a really thin USB cable though, and it probably wouldn't stand up to too many more watts.

The switches I use are 12V - 30A which should be more than adequate for their usage. I'm more of the mindset that Radioshack sells garbage. What usually happens is the switches mechanism of turning on and off will break (on toggles) or the pin/spring will pop out on the spst switches or not make contact anymore I'm not sure if you thought I was saying that I was using the buttons/boards from Ego batteries? If so, I should have provided more detail. Not really into super sub-ohms (On my scale that's anything below 0.5 ohm) It was when Ryedan brought up the heat flux subject as well as suggesting the steam coil calculator it gave me an added block of understanding into resistance wire/Kanthal. I am by no means an electrical wizard However, this isn't the 1st time I have wired a switch I know the smell of burnt electronics moderately well (and burnt clutches)