Volts & Ohms – Watts the Law?

If you’re using a mechanical mod (a mod with no inbuilt safety) or making your own coils, it’s worth taking a minute to try and digest a few safety aspects.

Ohms is the resistance of your coil. Volts and watts are the measurements of power that you will apply to your coil. And amps is the current drawn from your battery by the coil. Once you know how these all interact with each other, your coil building and vaping should be safe.

‘Man loses teeth when ecig explodes’! …. Yep it happens, and why? Because some vapers literally play with fire! They’re building coils, and using them on mechanical mods with no knowledge of ohms law and battery safety. The coil is drawing more current than the battery can supply and BOOM! Thats the end of their coil building days! Personally I would rather use a mod with built in protection, but if you’re determined to use a mech mod, lets take a look at the basics in…

Ohms Law

First you need to know the ‘ohms law’ lattering

V = Volt, R = Resistance (or ohms Ω) and I = Current (amps)

The rest is basic maths.

Staying within the amps range

It is essential to know the current that you will be drawing from your battery if you are using a mech mod. A battery used for vaping will (or should) have an amperage rate stamped on the side. So lets say you have a 20a battery.  You have a 0.4Ω (ohm) coil, and you will be vaping it on a fully charged battery which will output 4.2v. Heres the maths:

I = 4.2v / 0.4Ω  You would divide the 4.2 by your coil ohms of 0.4 giving you a total of  10.5A . This is well within range of your 20A battery.

As you vape the charge level of the battery will drop, so lets say you have been vaping for a while, and your battery charge level is at 3.9v

I = 3.9v / 0.4Ω This gives 9.75 amps, so the current that you draw from the battery will drop as the output volts drop.

How low can you ohm!

If you’re building your own coils for a mech mod, it’s handy to know what ohms you should aim for, and what is definitely too low. This set of maths will give you a figure for the lowest resistance that you should build your coil. This time let’s say you have a 10A battery.

R = V / I.  So on a fully charged battery the output power or V will be 4.2, divide this by your current (battery amps) 10A

4.2v / 10A = 0.42Ω. So 0.42ohms is the very lowest that you should build your coil, but its always safer to build a little above to save blowing your teeth out! So aim for 0.5Ω and you will be well within your safety range.

Another way to make sure you are in range, is to calculate with a slightly lower amperage than what your battery actually is. So instead of dividing by 10A, divide by 9A instead.

Variable Wattage/Voltage and Temp control mods will have safety measures built in. But your battery will still need high enough Amps to fire low ohm coils, otherwise it will show an error, and possibly even shut the mod down.

We hope this helps you to better understand ohms law and battery safety, but if you’re still unsure, come and chat with us over at Ceekays Vape Shack, and we’ll do all we can to help 🙂


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