Updated: 08/19/2020
Knowing and understanding Ohm's Law is helpful to all vapers and essential to those running mechanical mods or using rebuildable atomizers.
Part 1: Basic Electrical Theory
Electricity has several measurable properties, including electrical potential (Measured in Volts), current flow (Measured in Amps), and electrical resistance (Measured in Ohms).
Think of electricity as water flowing from a nozzle attached to a pump. The pump pressure would be equivalent to the potential, the restriction of the nozzle would be the resistance, and the amount of water flowing from the nozzle would be the current.
In our example, if we increase the pump pressure without changing the nozzle restriction, more water will flow from the nozzle. This is equivalent to increasing the voltage supplied to an atomizer, which will result in an increase in current flow.
Also, if our pump pressure remains stable, but we open the nozzle more, thereby decreasing the restriction, more water will flow from the nozzle. This is equivalent to using a lower resistance atomizer on a device providing a fixed voltage, resulting in more current flow.
There are two main things to takeaway from this section:
Point 1: If resistance is fixed, increasing voltage will increase current, and decreasing voltage will decrease current.
Point 2: If voltage is fixed, increasing resistance will decrease current, and decreasing resistance will increase current.
Part 2: Ohm's Law
Ohm's Law defines the relationship between electrical potential (Measured in Volts), current flow (Measured in Amps), and electrical resistance (Measured in Ohms).
Ohm's Law formulas typically uses the variable I to represent current in amps, V to represent potential in volts, and R to represent resistance in ohms. Ohm's Law can be stated in three ways:
I = V / R
R = V / I
V = I * R
If we know the value of two variables, we can use Ohm's Law to find the value of the third variable using the above formulas.
Example 1:
You have a battery with a maximum continuous discharge rate of 20 amps in your mechanical mod. You need to know if your O.5 ohm build is safe to use on this battery. Since we know more voltage causes more current, and our battery has a maximum voltage of 4.2 volts when fully charged, our maximum current flow will occur at 4.2 volts. So we use Ohm's Law:
I = V / R
I = 4.2 / 0.5
I = 8.4 Amps
So our build will draw 8.4 amps from our battery, which is well below the safe amount our battery can handle. So YES, we are safe running this setup.
Part 3: Power (Watts)
Power, measured in Watts, is the energy being used by your atomizer. More power generally produces more vapor, and may produce warmer vapor also.
Power comes with its own formula, P respresenting power in Watts, which can be written in three ways:
P = V * I
V = P / I
I = P / V
Just like Ohm's Law, if we know the value of two variables, we can find the value of the third variable using the above formulas.
Example 2:
Your variable voltage device is set to 4.5 volts, you attach a 1.5 ohm atomizer, what power are you vaping at? First we must find current using Ohm's Law:
I = V / R
I = 4.5 / 1.5
I = 3.0 Amps
So our atomizer will draw 3.0 amps of current, now we can figure the resulting power:
P = V * I
P = 4.5 * 3.0
P = 13.5 Watts
So we are vaping at 13.5 watts using this setup.
Part 4: Combination Formulas
Ohm's Law and Power formulas can be combined to produce several useful formulas for vapers. These formulas can be arranged in an Ohm's Wheel:
Example 3:
We can rework Example 2 using our new combination formulas. Your variable voltage device is set to 4.5 volts, you attach a 1.5 ohm atomizer, what power are you vaping at?
P = V^2 / R
P = 4.5^2 / 1.5
P = 20.25 / 1.5
P = 13.5 Watts
So we arrived at the same answer using fewer steps than in Example 2.
Example 4:
You want to vape at 50 watts using your mechanical mod with a fully charged battery. What resistance coil should you put in your atomizer? We know voltage, 4.2 volts, and wattage, 50 watts, so we use a combination formula to find resistance.
R = V^2 / P
R = 4.2^2 / 50
R = 17.64 / 50
R = 0.35 Ohms
So a 0.35 ohm build would give us 50 watts on a fully charged battery.
Part 5: Further Reading
Battery Specs & Safety:
Battery Basics for Mods: IMR or Protected ICR? By Baditude
Ohm's Law & Vaping Calculators:
Steam Engine
Please feel free to leave a comment if you have any suggestions or corrections.
Knowing and understanding Ohm's Law is helpful to all vapers and essential to those running mechanical mods or using rebuildable atomizers.
Part 1: Basic Electrical Theory
Electricity has several measurable properties, including electrical potential (Measured in Volts), current flow (Measured in Amps), and electrical resistance (Measured in Ohms).
Think of electricity as water flowing from a nozzle attached to a pump. The pump pressure would be equivalent to the potential, the restriction of the nozzle would be the resistance, and the amount of water flowing from the nozzle would be the current.
In our example, if we increase the pump pressure without changing the nozzle restriction, more water will flow from the nozzle. This is equivalent to increasing the voltage supplied to an atomizer, which will result in an increase in current flow.
Also, if our pump pressure remains stable, but we open the nozzle more, thereby decreasing the restriction, more water will flow from the nozzle. This is equivalent to using a lower resistance atomizer on a device providing a fixed voltage, resulting in more current flow.
There are two main things to takeaway from this section:
Point 1: If resistance is fixed, increasing voltage will increase current, and decreasing voltage will decrease current.
Point 2: If voltage is fixed, increasing resistance will decrease current, and decreasing resistance will increase current.
Part 2: Ohm's Law
Ohm's Law defines the relationship between electrical potential (Measured in Volts), current flow (Measured in Amps), and electrical resistance (Measured in Ohms).
Ohm's Law formulas typically uses the variable I to represent current in amps, V to represent potential in volts, and R to represent resistance in ohms. Ohm's Law can be stated in three ways:
I = V / R
R = V / I
V = I * R
If we know the value of two variables, we can use Ohm's Law to find the value of the third variable using the above formulas.
Example 1:
You have a battery with a maximum continuous discharge rate of 20 amps in your mechanical mod. You need to know if your O.5 ohm build is safe to use on this battery. Since we know more voltage causes more current, and our battery has a maximum voltage of 4.2 volts when fully charged, our maximum current flow will occur at 4.2 volts. So we use Ohm's Law:
I = V / R
I = 4.2 / 0.5
I = 8.4 Amps
So our build will draw 8.4 amps from our battery, which is well below the safe amount our battery can handle. So YES, we are safe running this setup.
Part 3: Power (Watts)
Power, measured in Watts, is the energy being used by your atomizer. More power generally produces more vapor, and may produce warmer vapor also.
Power comes with its own formula, P respresenting power in Watts, which can be written in three ways:
P = V * I
V = P / I
I = P / V
Just like Ohm's Law, if we know the value of two variables, we can find the value of the third variable using the above formulas.
Example 2:
Your variable voltage device is set to 4.5 volts, you attach a 1.5 ohm atomizer, what power are you vaping at? First we must find current using Ohm's Law:
I = V / R
I = 4.5 / 1.5
I = 3.0 Amps
So our atomizer will draw 3.0 amps of current, now we can figure the resulting power:
P = V * I
P = 4.5 * 3.0
P = 13.5 Watts
So we are vaping at 13.5 watts using this setup.
Part 4: Combination Formulas
Ohm's Law and Power formulas can be combined to produce several useful formulas for vapers. These formulas can be arranged in an Ohm's Wheel:
Example 3:
We can rework Example 2 using our new combination formulas. Your variable voltage device is set to 4.5 volts, you attach a 1.5 ohm atomizer, what power are you vaping at?
P = V^2 / R
P = 4.5^2 / 1.5
P = 20.25 / 1.5
P = 13.5 Watts
So we arrived at the same answer using fewer steps than in Example 2.
Example 4:
You want to vape at 50 watts using your mechanical mod with a fully charged battery. What resistance coil should you put in your atomizer? We know voltage, 4.2 volts, and wattage, 50 watts, so we use a combination formula to find resistance.
R = V^2 / P
R = 4.2^2 / 50
R = 17.64 / 50
R = 0.35 Ohms
So a 0.35 ohm build would give us 50 watts on a fully charged battery.
Part 5: Further Reading
Battery Specs & Safety:
Battery Basics for Mods: IMR or Protected ICR? By Baditude
Ohm's Law & Vaping Calculators:
Steam Engine
Please feel free to leave a comment if you have any suggestions or corrections.
