How to Calculate Ohm’s Law

What is Ohm’s Law?

Calculator on white backgroundOhm’s Law is a term that refers to one of the most fundamental relationships found in electronic circuits. It states that the current is directly proportional to voltage. This means that if you increase the voltage through a circuit with a fixed resistance, the current will go up. Conversely, if you decrease the voltage, the current will go down.

The electrical resistance of an object is a way of measuring its opposition to the flow of electric current. The inverse quantity is an electrical conductance. This is the ease with which an electric current passes through an object. Electrical resistance uses the SI unit ohm (Ω). On the other hand, electrical conductance is measured in siemens (S).

Why is Ohm’s Law important for vaping?

Safety is a vital concern in everything that we do. It is also a concern for vaping. When building your own mod, one of the things that you should consider is whether your coil builds are within the safe limits of your battery. This will allow you to further tinker and tweak your build until you get the vaping experience that you want.

Whenever you vape, you need to remember that you’re holding a metal tube with a high voltage battery. Either that or you have a high wattage box mod. You have these in your hands, or in your pocket. You’re also holding them near your eyes, mouth, and face. That’s a lot of power that you don’t want to leave to chance.

There are many of Ohm’s Law calculators online. These calculators are free to use and you can always use them to ensure safety while you’re building. We have one here on Vapor Vanity that you can use.

You can still be safe in your builds even if you don’t understand Ohm’s Law or how it works. As long as you know how to apply the results, you can have a safe vaping experience. However, I believe that understanding the logic and the inner workings behind the calculations that can ensure one’s safety is important.

The triangle pictured above depicts the relationship between voltage, current, and resistance. V = Voltage. This is the voltage of your battery. I = Current and represents the amperage drawn by your coil. R= Resistance and pertains to the resistance of your coil.

How do I calculate Current?

The formula for current is:     I = V ÷ R

Let’s say that you want to know the current of your coil. You have 3.6V available to power your coil. If your coil is 0.5Ω, you can now compute for the current of your coil.

I = 4.8V ÷ 0.5Ω

I = 9.6 A

The computations above show that with the resistance of your coil and the voltage of your battery, you can get a maximum current of 9.6 A. If your battery has a 10 Ampere limit, this means that you are operating below the cap.

How do I calculate for Power?

Wattage is the power generated at the coil you are using. If you want to calculate for wattage, the formula is:

P = V x I

Using the values in our example above

P = 4.8 V x 9.6 A

P = 46.08 W

The formula above shows that your 0.5 Ω coil with a 4.8 V battery will pull a maximum of 9.6 Amps and deliver 46.08 W.

How do I calculate for resistance?

It is important to calculate for resistance because it will help you determine the lowest coil resistance that you can run without exceeding the CDR of your battery.

The formula for resistance is:

R = V ÷ I

We know that the battery CDR is 10 amps. A good practice is to target 9 amps in your calculations. This is so you can have a 1-amp wiggle room. You also know that your max voltage for a single battery is 4.8 volts. Using the formula above, the calculation is then:

R = 4.8 V ÷ 9 A

R = 0.53 Ω

Based on the computation above, your safe lower limit with the 10-ampere battery is 0.53 Ohms. If you go any lower, you risk exceeding the current limit of your battery.

How do I calculate for Voltage?

Although this is not as vital for vapers, you can still calculate for the voltage in a circuit using the triangle above. The formula will be:

V = I x R

V = 9.6 A x 0.53 Ω

V = 5.08 V

What does Ohm’s Law mean for mechanical mods?

A mechanical mod is a metal tube that does not feature any regulation. It doesn’t have a screen with internal circuit boards. It doesn’t have any of the additional settings that a regulated mod has.

Mechanical mods can be dangerous because they don’t offer any protection from short circuits. They don’t have any protection to the battery in case of user-error. These are not devices for new users. Mechanical mods are for those who have an intimate knowledge of Ohm’s Law, battery safety, and other mechanical know-how.

However, if your mechanical mod is non-hybrid, Ohm’s Law will help you know what build you can safely put on your device. A non-hybrid mechanical mod is one that has a 510 pin and plate that separates and does not directly touch your battery.

Which common vaping problem can I solve using Ohm’s Law?

Dry Hits

Dry hits can result from dry coils and improper wicking. You either got the wattage wrong or you don’t have enough e-juice in the wick. This results in a burnt coil. You will get a foul taste and it can ruin your vape.

You can avoid this by always knowing the Ohms/wattage/coil resistance that your vape requires. Remember that wrong wattage can cause burning. Another thing you need to remember is to always feed the coil with e-juice and let it soak in before you start vaping.

Why is resistance level important in vaping?

Resistance level is important in vaping because it can determine the intensity of the taste and throat hit that you will get. If you use a low-resistance atomizer, it allows more current to pass through. As a result, the coil will generate more heat and more vapor gets generated. This will result in vapor with a less intense flavor.

On the other hand, a high-resistance atomizer means that the coil receives less current and the atomizer heats less. You will get a smaller amount of vapor but the vapor will have a more intense taste.

Additional resources

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