Hey everyone I have a question about how resistance matters using a Darwin. Is 8 watts on a 1.5 ohm atty the same heat as 8 watts on a 4.0 ohm atty at 8 watts? Does it just need to pull more power from the device to achieve it?
With a Darwin, if you can screw it on the thing it'll drive it well.
In theory 8 watts is 8 watts. A lower resistance atty will typically draw more amps to achieve the same 8 watts as a higher resistance atty; however, the higher resistance atty needs more 'voltage'.
In short, think of 'volts' as a big water tower on the hill. The bigger and higher that tower is, the more 'potential' energy it has stored up.
Amps would be how 'fast' the water flows from inside the tank out of a spicket somewhere at the other end.
Ohms has to do with the size of the pipes and how much water they can carry when everything is in motion. Lower ohm atties can carry tremendous bursts of energy really quickly (like using a really big pipe, or dumping straight from the tank into a pool). Higher Ohm atties would be more like using a very small pipe...you'd need more 'voltage/pressure' to push the same amount of water through it in a given time frame. With electricity and heat dispersing systems...the size/material ratio can sometimes be the opposite of water pipes (larger thicker coils might have more resistance, as they mix more 'non conductive' materials called insulators such as ceramic clay, silicon, or carbon into the coil's alloy which can add mass/surface area) but the numbers/principles are still going to be similar as with the water system.
In considering the water tower/pipe/nozzle model here, you should be able to quickly start imagining how all of these variables can be changed to impact how much, and how quickly you can move your water around. A big tower way up high gives you more voltage to play with (total source pressure). You can use massive pipes to dump out tons of water at lower velocities, or draw things down to a very small stream with intense amounts of pressure, and so forth.
At the end of the day, imagine you have a 5 gallon bucket at the end of your water system. For this analogy, we'll call the target gallons capacity of that bucket watts. Five gallons/watts is the same no matter what! But there's all sorts of stuff we can do to that water system to control how FAST, and how much PRESSURE is involved in filling that bucket.
So in theory, the total power being pulled is going to be the same between the LR and HR atty. The difference will be the amperage and voltage needed to do get your 8 watts output in a similar time frame.
Darwin uses a simple formula known as Ohm's Law to measure the resistance of the atty, and then tweak the voltage to your target 'wattage'. Meanwhile, it monitors the amperage for safety and limits you to around 3 amps at the high end.
Which is better?
To be honest, every single battery and atty is going to be slightly different in terms of which will drain the battery faster (HR or LR), but it seems that most of us are finding that HR gear has a slightly better battery life between recharges. Particularly if you like cooler settings below the 8.5 watt indent.
If you like higher settings, it probably doesn't matter much. LR in theory will heat up and cool off very quickly, so some people who like vaping at the higher temps might stick with LR atties even tho' the Darwin can dish out enough voltage to get up to 12 watts on just about any atty ever made. Some people also like how an LR attie gets as hot as it can get almost instantly, where a higher resistance atty might take a jiffy (100th of a second) or two 'longer' before it gets to it's target temp.
The 'major' advantage of the higher resistance stuff is that you will get MORE control over the actual temperature of your atty. I.E. With a 1.7 Ohm atty, the gate is wide open at very low voltages. You'll hit the amp limit of the Darwin at around 3.7 volts. Since the Darwin will only go down to about 3.4v or so, it is difficult if not impossible to run the LR atomizer at lower temperatures, plus the 'resolution' or curve of control that you get is very small (between 3.4v and somewhere around 3.7v). With LR, you're pretty much destined to run it wide open (as hot as it will go), and you probably won't notice much if any difference as you play around with the power setting wheel on the Darwin.
In contrast, if you have an HR atty from 3 to 4 Ohms, you have all kinds of room to play with! You can drop the power down to it's lowest settings and as you gradually crank it up notice that you don't run out of amps (Darwin has somewhere around a 3 amp limit for safety) until you get up around 6 volts or more! This means you can really fine tune in a sweet spot for your various liquids. Also, if you happen to like a liquid at a lower temperature, you'll see that the battery is barely trickling out the amps, and you might be able to go nearly twice as long before needing a recharge.
So, to answer your question. Yes, in theory 8 watts is 8 watts. In reality, it all depends on your atty, the way it is designed, and the liquids you like to use in it as to which performs better for you.
You can run anything you have on the Darwin and tweak it to it's peak performance. Use up your stock of LR stuff by all means (and if you have a favorite there's no reason not to keep buying them); however, HR stuff is going to give you a much greater curve of adjustment, is probably going to last a little longer (has more insulation material in the coils that tends to prolong the life of the coil), and may even give you a slight increase in time between needed battery charges.