Everyone is so concerned about ohms law that I'm scared they only preach it because they were told they should know about it. The only time ohms law is even relevant is in a mech mod, if you're using a regulated mod it's watts law you need to deal with, instead of preaching ohms law we should be preaching basic DC circuits and understanding when it's necessary to use which law.
Don't forget about Watts Law
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What exactly is watts law?
With ohms law you can determine watts and amps for a given resistance and voltage. It may not be AS critical for regulated mod users to know ohms law, but it is definitely helpful, it is important to know how much amp draw you are placing on your batteries when you fire an X ohm coil at Y watts. Unless you just trust your device to "keep you safe."
With ohms law you can determine watts and amps for a given resistance and voltage. It may not be AS critical for regulated mod users to know ohms law, but it is definitely helpful, it is important to know how much amp draw you are placing on your batteries when you fire an X ohm coil at Y watts. Unless you just trust your device to "keep you safe."
Watt's Law? P=I^2R [or P=(IR)I]? Yes, of course it's relevant; it's also implicit in Ohm's law. Still, for the purposes of vapers, isn't what we really want to know "is this safe on these batteries?" We can't find that information out in the common expression of Watt's Law because I is what we're trying to solve for and is not known at the time we work the equation. What we actually know-- or should-- is the voltage the regulated mod kicks out the batteries as "discharged" and the set watts, plus an accommodation for efficiency losses on the board. The common derivation of Ohm's Law that works for us is I=P/V; or to add the losses, something like I=1.05(P/V).
Actually what you're referencing is watts law, ohms law is the relationship between voltage, current, and resistance. Watts law is the relation ship between voltage, current, and power. Telling an inexperienced vaper to learn ohms law will have them assuming resistance is what matters in every case. If I put a .3 ohm coil on my Sigelei and run it at 50w, I'm gonna draw the exact same current as a 1 ohm coil at 50w assuming the voltage on my batteries stays constant. Since I don't use mech mods I've never once had to refer to ohms law, I just worry that most people saying "get a good understanding of ohms law" are only saying it because that's what they were told when they started vaping, if they don't know the difference between ohms law and watts law it tells me they don't actually have a good understanding of ohms law.
It's taught in electrician's school; the definition of the watt. P=(IR)I in Watt's formulation, more commonly expressed as P=I^2R. You're right, of course; this is implicit in Ohm's Law. We posted the same at the same time.
Again I=P/V is Watts law, ohms law states that current is directly proportional to voltage and inversely proportional to resistance. When figuring current from power you use watts law. I know most people know how to do this, it just scares me that so many people preach the importance of it yet don't actually seem to understand it that thoroughlyWatt's Law? P=I^2R [or P=(IR)I]? Yes, of course it's relevant; it's also implicit in Ohm's law. Still, for the purposes of vapers, isn't what we really want to know "is this safe on these batteries?" We can't find that information out in the common expression of Watt's Law because I is what we're trying to solve for and is not known at the time we work the equation. What we actually know-- or should-- is the voltage the regulated mod kicks out the batteries as "discharged" and the set watts, plus an accommodation for efficiency losses on the board. The common derivation of Ohm's Law that works for us is I=P/V; or to add the losses, something like I=1.05(P/V).
So even tho the resistance plays a part in the load on the cell you don't think that is important?
Ah! You're preaching semantics. Technically I agree with you; it is self-evident Ohm's Law classifies the relationship between volts resistance and current, and says nothing at all about applied power; and Watt's Law classifies the relationship of Power to the three variables in Ohm's Law. Practically I wonder if that's not more confusing than it's worth. My actual purpose it to prevent-- or at least reduce the frequency of-- people blowing themselves up because they don't understand the load they're placing on their equipment. Obviously, these people have no understanding of either Ohm's or Watt's Laws (or, likely, any idea whom Simon Ohm or James Watt might have been or why what they did is important).
A regulated mod will adjust the output voltage to give you the same wattage regardless of the resistance of the load/coil. If the load/resistance is within the range handled by the regulated mod.
Like cruise control. If you set it for 50 mph it does not matter if you have a 2.4 liter engine or a 5.0 liter engine.
You will still go 50 mph.
problems happen when you specify a wattage that requires more current from your batteries than they can safely provide.
Like setting your cruise control on 100 with a 1.8 liter engine.
Something is gonna blow.
Like cruise control. If you set it for 50 mph it does not matter if you have a 2.4 liter engine or a 5.0 liter engine.
You will still go 50 mph.
problems happen when you specify a wattage that requires more current from your batteries than they can safely provide.
Like setting your cruise control on 100 with a 1.8 liter engine.
Something is gonna blow.
in a regulated mod the resistance makes no difference on the battery, at 100 watts with a full 8.4 volts there will be approximately 12 amps of draw on my battery, the place where the resistance comes into play is on the device itself, my batteries may discharge 12 amps but with a .3 coil at that wattage (5.5 volts) my device will have around 18 amps of current drawing through it, it's essentially two seperate circuits
I disagree with OP, although he is correct on the technical side. In point of fact, in a regulated mod, the coil resistance is meaningless to the load on the cell so long as it falls within the parameters of the board so it fires at all. The cell can't "see" the atty resistance; it's downstream of the board. What matters to the cell is the load placed on it by the board. That is set watts, plus board efficiency losses, divided by battery voltage.
Haha I know I'm getting picky, it's just kind of a pet peeve of mine that people preach the importance of it without actually fully understanding it themselves, it just worries me that some new vaper gets told to worry about ohms law, and if they actually follow that correctly they're going to assume that resistance is the only thing that matters in every scenario
And to get technical you have to figure in the loss in the voltage converter circuitry in the mod.
Which tend to be more efficient at higher wattages than at lower wattages.
Which tend to be more efficient at higher wattages than at lower wattages.
Yes it does, as watts is set, the voltage to make up the watts is decided by the ohms of the coil
Which is a reason I like mods that display the current. such as the VTC mini.
Although I am not sure if that is battery or output current.
yes but only the voltage from the board. There is no way to adjust the voltage of the battery cells, they only change as they drain, coil resistance has absolutely zero to do with what current is drained from the batteries, that's where watts law comes into play
you are putting way to much faith in chips that can't even do step down as they rely on the cell to decide what they can run
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