Looking to start building coils

Hardware Rebuildable Atomizers and Tanks
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Right. The batteries are series connected (doubling the maximum available battery Voltage potential). Those batteries (should, advisably) have the same maximum continuous discharge Current ratings (same make/model batteries).

(For a given physical coil-wicking setup built on the same deck), your best “gauge” looking back in time to previous practices is the Power in Watts (reflecting peak/average Temperatures previously preferred).

Working Backwards from “Load” to “Battery”:
Knowing the (Load) Watts, add a fraction of that amount ( < 1/20 ?) for Mod Power consumption, and from that sum of Powers (Load + Mod), calculate the common (maximum average) continuous total discharge Current flowing through the battery cell(s) at a fully-charged Voltage (4.2 Volts per cell, or any particular somewhat lower voltage perhaps more representative). The maximum continuous discharge Current rating of the batteries utilized should be at least 4 times (better yet, ~5 times) the multiple of the calculated Current (process described directly above), for best performance (minimizing “drooping”).

As long as the Mod in question (at the output-drive point) can generate sufficient Voltage corresponding to some (composite, net load) Current to dissipate N-Watts of Power in some (composite, net) Coil(s) Resistance, the Mod should be able to do it. The specified range of possible load Resistances reflects the electrical limits of the device.

Again, the “15 W” displayed is just an (arbitrary) number (generated from calculated Heat Flux) ! :nerd_face:

Stainless Steel is lower Resistance than Kanthal A1/APM - which enables one to construct (feasible, in this case, single) coils [such as using ~5 turns (SS), as compared to using ~2 turns (KT), respectively).

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For some semi-energetic “heavy-duty prior Nerditude”, some important “factors” are discussed here:

Summary:

The use of thicker wire gauges in order to achieve a lower total Coil(s) Resistance requires more Coil Power (Watts) in order to achieve the same 10%-90% Temperature Rise Time (of increases in the Temperature of the Coil/Wick Interface). As a result, the particular coil wire gauge that is used in creating a coil(s) determines a specific range of Coil Power (Watts) within which an “acceptably fast” 10%-90% Rise Time can be realized - with the required amount of Power (Watts) increasing with wire thickness. Maximizing (inner) Coil Surface Area while minimizing Coil Mass minimizes 10%-90% RT.

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The amount of power has a lot to do with the amount of cooling your coil gets, as well as with the resistance, how well your wick performs and how you suck on your mod. Also coil material and type of coil play a role…
So for every new coil you use, you should start very low and build up to where you feel good about it.

Some metals heat up and cool down very fast. Some wire types, same thing. Very thin wires heat up fast and thick bulky wires/coils will need more power to heat up and more time to cool down.
Coils are cooled by both liquid and airflow so the harder you suck and the better your wick works, the more power your coil can handle.

I’ve learned not to trust the recommended wattages on commercial coils because I’ve ruined plenty. It’s also one of the reasons why I love TC (temp protection) so much because if you choose a wattage that’s too high or your wick can’t keep up, you mod will shut off (or regulate) power so you don’t burn your cotton, ruin the coil and give you an unforgettable experience.

15W for a .17ohm coil is really low. I’d start around 40W and build up from there. If you have a .3ohm coil, start from around 30W and build up. Once you’re building coils and testing different options, you’ll get a feel for what is acceptable and what not. After a while, most people find their preference and stick with that and then there’s no more (or a lot less) experimenting.

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Were those failures loss of plating (and corrosion interfering with heat-transfer), or actual breakage ?

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24

Some are good but a lot were over-estimates, especially on the higher wattage range. In the beginning I needed a good throat hit and I guess I pushed the coils too much at the higher recommendation, burnt cotton.
I quickly switched to DIY coils. At least you can make what you want that way and use whatever metal you prefer. Both kanthal and nichrome taste like metal to me and ruins the taste of a juice and neither can be used for TC to prevent scorched wicks.

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So it was a matter of coil-wick interface surfaces reaching temps higher than desired (at given wattage).

Why not just dial-back on the wattage, then ?

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I have noticed I have been burning through coils a lot lately trying to get a decent throat hit and not feel like it’s empty air when going to the higher end of the recommended wattage. 15 watts just seemed so low on a home made coil. So hypothetically if I’m gradually going up in watts to find my sweet spot the vapor would probably get too hot for my lungs long before i push the coils to a dangerous point? I guess I’m worried about overdoing it.

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If you make your own coils and burn your wick, just re-wick and you’re good to go again.

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That’s what is incentivising making coils for me is the ability to re wick and not just throw the whole coil out. Since you mentioned pre made coils tend to be rated too high would it be safe to assume that as long as I didn’t go above that wattage when pushing it I’d still be within a safe zone? I like knowing limits lmao. Then again if it was at too high of a wattage it’d probably burn the cotton and I’d notice before the coil itself got damaged. I really think I’m just overthinking all of this. Lmao and as I type this my overloaded brain finally gets what you mean! I slowly work up in wattage that way I find my own limits and the cotton would burn first if it was too high which is a much safer alternative to jumping 40 watts and melting a coil. Ugh I feel like an idiot. Thank you guys so much.

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The “15 W” display (in the Steam Engine widget) is an ARBITRARY NUMBER. Forget about it !

One has no choice but to increase Power to find a suitable Wattage level. It is not the coils made of wire that “fail” (by reduced thermal transfer due to plating loss and corrosion, or by the coils physically “breaking”). It is the coil with a (seemingly, from what you are saying) wicking material that is not (at least practically) interchange-able.

The “limits” (of when Temperatures in the coil-wick interface become too high for the wicking material) are a function of how well the wicking material is kept saturated with e-juice and what kind of air-flow takes place around the coil-wick assembly and the average coil-wick interface Temperatures resulting from one’s vaping techniques, as well as what the particular amount of Watts of Power to the (net, composite) coil loads are.

Making and/or using coils that allow for replacement of the wicking material is highly desirable.

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So the conclusion I’ve come to is the main thing I need to pay attention to is not turning the watts up higher than the batteries can handle. I read that two 15 amp batteries can handle up to 80 watts safely. So as long as I stay below my battery’s max the ohms, wire used, and wattage level mostly just affect flavor and cloud production and beyond that it’s just the wicking material that could potentially have a hard time keeping up. Not the coil itself. I seriously hope I’m getting it. I’m starting to worry about my brain function. Lol

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(For safety), do not even use batteries in your Mod (advertising up to “N” Watts maximum) that do not conform to the results of the calculated described below (from one of my posts above).

Working Backwards from “Load” to “Battery”:
Knowing the (Load) Watts, add a fraction of that amount ( < 1/20 ?) for Mod Power consumption, and from that sum of Powers (Load + Mod), calculate the common (maximum average) continuous total discharge Current flowing through the battery cell(s) at a fully-charged Voltage (4.2 Volts per cell, or any particular somewhat lower voltage perhaps more representative). The maximum continuous discharge Current rating of the batteries utilized should be at least 4 times (better yet, ~ 5 times ) the multiple of the calculated Current (process described directly above), for best performance (minimizing “drooping”).

Right. Control (coil-wick interface surfaces) Temps so that one does not “scald/burn” wicking material.

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Note that the “liberal” margin (of the ratio of the maximum continuous discharge Current rating of the batteries used divided by the worst-case highest Current draw from the Mod) of something on the order of 4 - 5 is stated (in order to minimize battery “voltage droop” effects when Current is drawn from the batteries). One (could) conceivably reduce that margin (to something less than a factor of 4 -5) without reducing safety from battery “melt-down” (so to speak) - but it remains important that the amount of battery “voltage droop” does not significantly degrade the operational performance of the Mod itself during use.

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Forgot to EDIT the following:

The above fraction (of Mode electronics power consumption relative to Coil Load Current) would be less than “1/20” (when considered in units of Power). Less than 1% ( < 1/100 ) is more like it. At that point, Mode Power consumption can probably be ignored completely in performing the described calculation.

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For some reason I’m having a hard time getting what you’re saying to click. I’ll continue to read over it. In the meantime, you said that batteries in series raise the voltage not the amps and the other way around when they are parallel. Does that mean that instead of trying to pull 20 amps out of one 15 amp battery and stressing the battery that the higher voltage is sharing the load? When voltage starts to droop the current being pulled goes up, correct? For example would having one 18650 3.7 volt 30q 15 amp battery be under more strain with a 20 amp pull than two 18650 3.7 volt 30q 15 amp batteries connected in series? I’ll include a pic of the screen of my vape. When I draw it pulls 19.8 amps. I’m adding all the information I can relevant or not.

20200425_153207
20200425_1532071932×2576 473 KB

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For series-connected batteries (or Resistances, Capacitances, Inductances as well) the Current is the same (a measure of the amount of Charge Transfer per unit Time). The Voltage increases for series-connected batteries (a measure of the amount of potential Energy per the amount of Charge accumulated). Current and Voltage are (thus) two different types of things. Better to think in terms of Current flow (from a Source, and into/through a Load).

Not necessarily. In the case of a battery (directly, hard-wire) connected to a Resistance, not at all. In the case of a (Power) regulating Mod, the device is likely to (attempt) to draw more Current (from the battery Power source) when the (Load) Voltage decreases. However, when the battery supply Voltage [as opposed to the Load Voltage across the Coil(s)] “droops” (due to a “heavy Current load” on it/them), one depends entirely upon the particular Mod device electronic circuit design topology to have the “Voltage compliance” required in order to operationally function as intended.

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Note: I am concentrating on what is actually going on (so as to keep pertinent material brief).

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Do you know the (approximate) Power in Watts that you want to be able to operate at ?

If so, divide that value of (maximum) Power by the (net, composite) Coil Load Resistance, take the Square Root of the result, and then multiply by a “margin” factor of (say) greater than something in the range of 4 or 5. The result is the (minimum recommended value of) the Maximum (continuous discharge) Current rating of the battery (or series-connected batteries) that one would want to use.

The rest is about managing to not overheat the wicking material (in/through) the Coil(s) during use.

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The above paragraph nicely “sums up” the various trade-offs surrounding the choice of what wire gauge (thickness by diameter). The larger the wire, the slower will be the 10%-90% Rise Time of coil-wick interface Temperature when activating Mod (from a “cold start”, or from some intermediate temperature as well). The (only) remedy for that - in order to increase that 10%-90% Rise Time of Temperature (for given system parameters relating to coil, wicking material, and air-flow) - is to increase the (net, composite) Coil Load Power dissipated (Watts). This is why some prefer to use thinner Coil wire.

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I’m definitely doing this wrong. When I insert 65 watts divided by .2 ohm and do the rest I get 90. Which i feel is entirely wrong.

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I think I’m gonna give up on trying to understand this. I’ll just stick to a safe area in ohms and keep my watts lower than what i usually use and won’t push it. Im driving myself nuts with this lol. I appreciate it though.

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Your recent numbers lack context. What is your desired/anticipated (maximum) Mod output Power (in units of Watts) to the Coil(s) ? How many batteries connected in series in the Mod power supply ? :thinking:

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