So I've been trying different coil builds lately. I was looking at a coil that would come out to about 0.42 ohms. If i were to use this on a regulated device at 50 W the corresponding values would be 4.58V, 10.91 A, 0.423 Ohms, 50W as mentioned. My confusion lies in that I know we shouldn't exceed the amp limit especially on mechs, I own one. But what about the voltage? Isn't this exceeding the 4.2V at full charge, is this still safe even on a regulated device? When I was starting out I was told not to worry about the other values on a regulated device, do I not understand ohm's law as well as I thought I did? I've also considered using this in my mech since it does not exceed the battery amp limit but now i'm curious about the voltage aspect
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You cannot "exceed" a battery's voltage, except by overcharging it. When discharging, the battery simply outputs voltage equal to its charge state (generally 3.5-4.2v). Your device then "regultes" that voltage to whatever is required to match the output power (wattage) setting.
Whether you're talking mechanical or regulated devices, power (wattage) is the conserved quantity. Watts in equals watts out. On a mechanical there is no regulation, so the "in = out" rule holds true for volts as well -- whatever charge state your battery's at, is how many volts will be delivered to the atomizer, and watts will be determined by this voltage level in conjunction with the resistance of the attached load. Not so, on a regulated device. You get to set the watts to whatever you want. The device will then draw that many watts, at whatever voltage the battery is at, and convert it to however many volts it needs to deliver those watts to the atomizer at whatever resistance the device reads it at.
Watts = Volts * Volts / Ohms
Amps = Volts / Ohms
Therefore:
Watts = Volts * Amps
Therefore:
Amps = Watts / Volts
At 50 watts, and assuming a charge state of 3.2v for safety (very low charge = max amp draw), you are drawing a maximum of 50/3.2 = 15.625 ... add 10% to power the device itself and you're looking at about 17.1 amps drawn from the battery, all told. What battery are you using?
Whether you're talking mechanical or regulated devices, power (wattage) is the conserved quantity. Watts in equals watts out. On a mechanical there is no regulation, so the "in = out" rule holds true for volts as well -- whatever charge state your battery's at, is how many volts will be delivered to the atomizer, and watts will be determined by this voltage level in conjunction with the resistance of the attached load. Not so, on a regulated device. You get to set the watts to whatever you want. The device will then draw that many watts, at whatever voltage the battery is at, and convert it to however many volts it needs to deliver those watts to the atomizer at whatever resistance the device reads it at.
Watts = Volts * Volts / Ohms
Amps = Volts / Ohms
Therefore:
Watts = Volts * Amps
Therefore:
Amps = Watts / Volts
At 50 watts, and assuming a charge state of 3.2v for safety (very low charge = max amp draw), you are drawing a maximum of 50/3.2 = 15.625 ... add 10% to power the device itself and you're looking at about 17.1 amps drawn from the battery, all told. What battery are you using?
I'm using LG HE2 20A batteries. So what i've been doing is maybe 50 W at max charge and then tapering down to 30/40W as the battery approaches dead or low charge. If i'm using this battery at max charge like you said it's trying to draw 50/4.0V= 12.5 + 10%= 13.75A. I guess my confusion is at max power/ lower power trying to use a watt value that the battery technically can't handle at the respective charge. Is this stressing the battery or am I simply not getting the desired wattage but simply what the device can output (in a regulated device)
Those should be good up to a limit of about 60w per cell (so, 120w in a dual-cell device, or 180w in something like a Wismec Reuleaux.)
For safety's sake, always assume your battery is dead-dead-dead. Call it 3.0 volts under load (most mods cut off somewhere around 3.3-3.5). Multiply that by your battery's amp rating, and you'll have the max watts you can safely pull from the battery at low charge. The 60w I mention above is for a cell at 3.0v. You can technically go up to 80w at 4.0v, but unless you're constantly monitoring your battery's charge state, just assume that it's always 3.0 in your safety calculations and you'll be in good shape.
Ok great! I guess I've still been operating in a safe realm without knowingly doing so. I thought I had a decent grasp of ohm's law but this helped more.
Often, people are introduced to Ohm's law as it applies to mechanical devices, where the amp draw is determined by the atomizer's resistance, and then never educated as to how it applies (or doesn't) to a regulated device. As a consequence, new users often end up with some confused notions about how it all works. Note that the atomizer resistance (ohms) is nowhere to be found in the equation Amps = Watts / Volts. That's because amp draw on a regulated device is determined by watts setting and charge state; atomizer resistance plays no part.
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