Tag Archives: resistance

Sub-ohm Vaping


There are many places on the Internet where you can find out about batteries but this counts for nothing if you purchase a clone by mistake.

Brand names like Efest, Panasonic, AW, Sony, MNKE should only be purchased from highly recommended suppliers. Some brands like AW will only sell through authorised resellers and there was a spate of clones on the market recently. In short, do your homework.

There are many good forums like Planet of the Vapes and UK Vapers where people will answer your questions.

A good vendor will be able to provide you with the performance details about the battery. The good news is that there are a growing number of batteries able to cope with a constant current of up to 30amps. With all vaping, ensure that your battery uses “safe chemistry†and follow Rule.1: Never scrimp when buying batteries.

Ohms Law

From when you first started coiling your atomisers you ought to have drummed V=IxR into your mind, where V is the battery voltage, I is the current in amps and R is the resistance in ohms.

To find out what current you are sending through your mod you need to divide the maximum battery voltage (commonly taken as 4.2V) by the total resistance.

When you are measuring the resistance of your atomiser make sure that you use a quality ohmmeter (like this one) capable of reading to two decimal places.

Parallel Coils

If you don’t know how to work out the total resistance when you place coils into parallel (dual/tri/quad) then bookmark this page and it will work out the total resistance for you.

Current from a fresh 4.2V battery



0.95 ohm

4.40 amps

0.90 ohm

4.70 amps

0.85 ohm

4.90 amps

0.80 ohm

5.25 amps

0.75 ohm

5.60 amps

0.70 ohm

6.00 amps

0.65 ohm

6.50 amps

0.60 ohm

7.00 amps

0.55 ohm

7.60 amps

0.50 ohm

8.40 amps

0.45 ohm

9.30 amps

0.40 ohm

10.5 amps

0.35 ohm

12.0 amps

0.30 ohm

14.0 amps

0.25 ohm

16.8 amps

0.20 ohm

21.0 amps

0.15 ohm

28.0 amps

0.10 ohm

42.0 amps


When you are vaping at low ohms you might want to consider using a lower nicotine liquid than you would normally vape. The volume of nicotine entering your body is greatly raised and you can suffer from headaches and nausea. Serious cloud chasers often opt for a zero nicotine high VG liquid.


As a final caveat, in some research carried out by Doctor Igor Burstyn and Dr Konstantinos Farsalinos it has been identified that acrolein and formaldehyde are formed at high temperatures/low ohms/high currents/high voltages. Although there is more research to be completed in this area, to discover at what quantities and how harmful, it is one reason why some people shy away from low sub-ohm vaping.

The Fear

I think an additional worry from many is the introduction of maths. Delving back into the mists of time I remember how worried parents were coming to parents evenings (when I used to teach) in case they were asked questions. My wife ran out of her ability to help the kids with science and maths homework somewhere around Year 5. It was clear that many adults out there struggle with mathematical operations. Taking the (to some of you) simple V=I.R may as well be written as follows for some people as:

Looking over some threads on an online forum I am struck by the number of people seeking reaffirmation for their coils, praise from their peers for a job well done…but more so by the volume of vapers seeking help with their ecig wire woes. One of the lovelier aspects of online forums is a sense of community, a place where those with experience or knowledge can give others a helping hand or moral support.

It does worry me though; there are many vapers who do not interact online and the ease of buying cheap mods from China is ever-present. Even with forums and Facebook we see people charging their Egos in odd ways…not to mention the ability for people to not realise the information they are being given may not be the wisest advice:

See, the thing is, fear is a good thing. Our ancestors were either fantastic at fighting or, more wisely, even better at hiding because they were afraid of being killed. Fear is the thing that is hardwired into us to protect us from ourselves.

Take the wobble of an atomiser on top of a mod due to a gap, for example. We are afraid that this wobble may end up ruining the threads of the atty or the mod and so we try to obtain a flush fit – and for those unable to do so there is always the OCD washer.

Part of our brain, the bit we really don’t have much control over, a relic from our primal selves gives us this ability to recognise danger and avoid it. This said, I can’t count the number of times I have touched a wick to adjust the coil and left myself with a cool mini-branding. Luckily the thalamus clicked into gear, got in touch with the sensory cortex, used the hippocampus and activated the hypothalamus faster than it took to write that and yanked my hand away from searing my flesh.

So it’s fine to fear your coils, it’s OK to find the maths perplexing; it’s just not OK to allow your child to purchase One Direction CDs. That scares me. And those of us with knowledge to share, don’t grow weary when seeing that question posed for the millionth time – it’s because there’s now 2.1million of us out there, each at a different stage in their vaping journey.

And let’s stop telling people that boiling batteries is good for extending the mAh rating…no matter how much I may have tittered at the notion.

Dave Cross