Variable wattage mods -- does coil resistance effect anything besides battery life?
[Posting here because I'm too new to have enough posts to post in the VV/VW forum]
I'm still pretty new but getting a fascination with VV/VW mods, like maybe a Innokin SVD from Fasttech.
When using a VW mod, what does coil resistance effect besides battery life? From what I've read, part of the idea behind a VW mod is to be able to use a fixed amount of power via the mod detecting coil resistance and adjusting voltage output to produce the desired wattage.
Presumably this means that for a given wattage the coil resistance wouldn't matter to anything except battery life, with a lower resistance coil causing lower battery drain. But something else tells me it's not that simple and that there may be other differences. I'm just speculating but maybe coil life might be better with lower or higher (my guess would be higher) resistance or some other factors.
Can anyone enlighten me further on coil resistance selection when using a fixed-power (variable wattage) mod?
I am pretty new myself and would love to learn more about this. I have an iTaste SVD and love it, but I don't understand much about the VV/VW world. I know that when I started, I was vaping at a very low (underpowered) setting, so I was leaking everywhere. I am getting better now, but still I have so many questions.
I've seen the voltage vs. resistance charts with the ideal power envleopes and I understand the basic electrical properties (ie, Ohm's law) but why you'd pick a coil of 1.8 vs. 2.5 when using a fixed-wattage mod is kind of mystery.
I get why you'd choose a specific resistance when using a fixed-power battery, since the coil resistance is the only way you'd adjust power output. A variable voltage (but not wattage) "spinner" battery would seem to make less of a difference, provided you "did the math" and made the appropriate voltage adjustment relative to the coil resistance to get the desired wattage.
The ideal power envelopes seem slightly larger on higher resistance coils, presumably allowing for a finer-grained "sweet spot" and maybe that's what it's about.
Variable watt PV's are supposed to "automatically" adjust the power to a change in the resistance of the head you are using in order to maintain your original setting. And they are of course regulated. Different resistance heads will deplete a battery at different rates but the difference should not be too significant if you are using good batteries and a good charger.
A good VW PV should be an advantage to a newer vaper, as they are closer to set and forget.
A 1.5 ohm coil draws 2.6 amps at 10 watt whereas a 2.5 ohm coil draws 2 amps at the same wattage, according to ohm's law. In theory, then, a higher ohm coil should use less power and the battery should last longer. However, voltage conversion efficiency (or something of the sort) come into play and things aren't that simple in real life. Someone with more expertise should be able to answer why that is and how battery times are actually affected. I haven't noticed much difference with different coils.
how big of a difference does quality of batteries matter you may ask?
standard vaping is ~2amps... ~1.2 being the low end and ~3amp being the higher end. If you look at some batteries there is very little difference and with others its night and day.
depending on the atomizer, higher resistance coils CAN but not always have thicker gauge wire which can lead to a longer lifespan as a cooler vape. LR coils at the same wattage can get hotter quicker usually due to smaller gauge. both of which affect vapor production and flavor, which of course is also dependent on your specific type of atomizer.
I think that's the main reason, Well put.
Originally Posted by mobocracy
Too low of resistance and you won't have as much useable range. To high R and you won't be able to get it hot enough.
Something I've thought about but don't know if is true is that higher resistance coils have longer wire so that the overall power (heat) is spread out over a larger area. This would give you a cooler vape at the same power or allow you to apply more power without burning.
The reason I don't know if it's true, is because they might just use smaller wire to get the higher resistance so the overall length wouldn't be increased. Then wire surface area would actually decrease with higher R.
I'm just putting my experience out there. I use low resistance micro coils, preferably at 1.3Ω @8W on either Smoktech SID or Innokin MVP v2. Since switching to LR my batteries seem to last, well, around the same. Maybe a tiny bit longer, around 30minutes to 1 hour extra use. Hard to say without putting it all on paper.
At any rate, my coils heat up pretty dang fast, produce loads of vapor, and I don't find myself hitting the cut off very often at all. This might be one reason my batteries "seem" to last longer. Must also consider that if you're trying to get the same hit off a standard resistance coil as you would on a low resistance, you will definitely need to take a much longer pull or kick the watts up even higher.
All I can say for sure is, I use two APVs, and I MUCH PREFER low resistance coils. Why? I already said why! PREFERENCE! So the answer to your question is as simple as that, i.e. use whatever you prefer!
Vape well, vape often!
The issue of battery output vs device output in a regulated PV and if high voltage gives better battery life are great questions and they come up every once in a while here. Rader2146 has answered these much better than I ever could here.
It looks complicated, but it's not too bad to follow though. In a nutshell, the battery in the PV always puts out the voltage it has because of it's state of charge (between 4.2 and about 3.3V), not the volts that you set the PV at, or the watts at if it's a VW device. What happens is the PV exchanges current (amps) for voltage to make the power you asked for. It's the watts the PV puts out that determines how long your battery will last.
Read Rader's blog for all the details.
For a given fixed power, would the coil temperature be meaningfully different between different resistance coils? In theory, a lower resistance coil and a higher resistance coil operating at the same wattage should operate at the same temperature as they are both absorbing the same power, just at different voltages. There may be a time-to-heat difference, but only by milliseconds.
Originally Posted by DKP#
I can see, though, where coil durability would matter if the higher resistance coils are more wire (thicker or longer) than lower resistance coils, but it's kind of not clear to me how (short of burning them up) coils wear out, either. Maybe they get buildup over time that causes them to need more power (longer draws) to reach vaping temperature.
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