Sub-Ohm Vaping Basics
11 January 2016
If you’re using a sub-Ohm tank and coils (sub-Ohm means coils with a resistance of less than 1.0 Ohm), it's important you understand a few basics to avoid liquid in your mouth, or liquid leaking out of airflow channels, etc.
In addition to the technique required, you must ensure the battery (power source) you're using is capable of operating at the low resistance of your coil. The wrong battery with low resistance coils is a serious safety issue (overheating/explosion/fire) so if in any doubt get more information first.
Sub-Ohm vaping has become popular with users who want increased vapour and/or more flavour.
Sub-Ohm vaping is not for everyone so don't think this is or should be every vaper's goal.
We've included some specifics about the Eleaf Melo for clarity, but this article is relevant to most sub-Ohm devices, you just need to fine tune everything to your device.
How does sub-Ohm vaping work?
All mechanical mods, variable voltage/wattage regulated mods and e-cigs are electrical devices powered by a battery.
The practice of using or building low resistance coils is directly related to the principles of Ohm's and Joule's (electricity) laws which state that given a non-variable voltage source (such as the battery in a mechanical mod) you can increase the power output (wattage) by decreasing the resistance (Ohms).
Low resistance/sub-Ohm coils are not always necessary when using a variable voltage/wattage device, but when they are required it is so that the device can operate at a higher wattage output.
As the resistance decreases the amperage will increase (your device will use/need more amps to supply the current needed) which increases the strain on the battery, which in turn can increase the heat that the battery and coils generate.
You must ensure that you never exceed the amperage limit of your battery.
The concept of sub-Ohm vaping is simple, however, users must understand exactly what they're doing before use. Ensure you follow safety rules to avoid your device failing which could result in injury or property damage from fire or explosion.
Ensure the power, whether it be a wattage or voltage level, is in the correct range for your coil. Most coils have this range (their minimum and maximum) printed on them although it can be hard to read at times because it's very small.
In the case of the Eleaf Melo 0.5 Ohm coils, the wattage range printed on the coils is 20-30W.
For sub-Ohm vaping in general an average wattage output of 30-35W is probably a guide as to the sort of power required.
The Melo is designed to match the Eleaf iStick 30W mod which has a range of 5-30W but if you set the wattage too low the liquid cannot vapourize, and instead it will gurgle away, the liquid may get darker in colour, and you’ll end up with it in your mouth or seeping out wherever it can because it has nowhere else to go every time the fire button is pressed.
The actual range you are likely to need to vape the Melo at is about 25W.
e-Liquid for sub-Ohm vaping
You also need to use a good quality e-liquid with more VG than PG (VG is thicker than PG and produces a lot more vapour, and reduced throat hit).
An 80% VG ratio is often ideal for very low resistances but you may find anything from 70% VG to a 50% VG is the right choice for your coil.
Be aware that 6mg (0.6%) nicotine is probably an absolute maximum strength e-liquid to use in any sub-Ohm device.
If you can’t take the hit from the increased vapour from the VG content of the e-liquid, turning the power down will cause more problems than it solves, instead you need to reduce the nicotine strength.
You may also find higher strength e-liquids (above 6mg) taste burnt or harsh with a sub-Ohm coil.
Sub-Ohm lung inhale technique
When you press the fire button you need to inhale directly into the lungs. Sub-Ohm vaping, which usually has a looser more airy draw, is designed for direct lung inhale, as opposed to the more traditional mouth to lung inhale.
Don't let the juice build up in the coil (unused) because it will boil away like a kettle while the fire button is pressed - you want the juice to be taken into the coil and then vaped. As a guide a 3-4 seconds draw is about average.
If the liquid builds up in and around the coil you will hear it crackling and popping away quite loudly.
Avoid dry hits if you're using cotton coils
When you're using cotton coils, it's very important to ensure the coil is thoroughly saturated in e-liquid to avoid dry hits (to avoid the cotton inside the coil getting burnt). The burning releases unhealthy chemicals, a bit like burnt toast, and although different chemicals are produced/released, neither are considered good and should be avoided.
Sub-Ohm safety - mechanical mods
Ensure you keep your mechanical mod clean - this includes all threads, vent holes, contacts, and the switch.
If you're using a spring-loaded switch be mindful of how stiff it feels. If, over time, the spring seems to be getting softer to press it's likely wearing out and needs to be replaced before it fails.
Consider upgrading to magnets next time round.
Use your mod's locking mechanism when you're not using it.
Never use an unvented mod to sub-Ohm vape (the more vents the better).
You will also want a mod with low voltage drop. Voltage drop is the amount of voltage lost when the electricity travels from your battery through your device and to your coils. For this reason the most preferred are mods that feature a single piece tube, fixed position contacts, and magnetic switch.
Spring-loaded or threaded contacts, multiple piece tubes, or telescoping tubes might be convenient but will raise voltage drop. While spring-loaded switches can wear out quickly or fail.