These days, "sub-ohm” is one of the most common phrases you’ll see when looking at vaping devices, tanks and atomizers. Sub-ohm vaping is all about using huge power to generate room-filling vapor clouds. Since many of the people who vape are happy to enjoy bigger clouds if they can, sub-ohm vaping has taken off very quickly. Every advanced vaping device has sub-ohm compatibility, and sub-ohm tanks are the most popular and common vaping accessories available today. If you’ve been vaping for a while, you probably own a sub-ohm device already. If you’re new to vaping, you’ll probably consider a sub-ohm device when it’s time to upgrade.
Switching to sub-ohm vaping means that you’ll enjoy bigger vapor clouds and richer flavor than ever before. It also means you’ll use atomizer coils that operate at high wattages and produce high-amperage currents from your batteries. You’ve probably seen some news reports discussing the terrible accidents that a few people have experienced with vaping devices and batteries. The 18650 battery cell – the most popular type for vaping – stores an incredible amount of power in a small package. The 18650 cell also powers electric vehicles. A two-battery vaping device has about the same battery capacity as a notebook computer designed to run all day – that’s a lot of power. If you respect the power of your vaping batteries and care for them properly, sub-ohm vaping is not dangerous. Treated improperly, though, a lithium ion battery can cause great damage. In this article, we’ll discuss the risks and explain how you can enjoy the world of sub-ohm vaping safely.
What Is the Potential Danger of Sub-Ohm Vaping?
When you’ve read about e-cigarette battery accidents in the news, you’ve probably noticed that most reports use the phrase "e-cigarette explosion” to describe those incidents. The lithium ion batteries used in e-cigarettes don’t explode, though – they vent hot gas. If an e-cigarette traps that gas because it has no vents, the e-cigarette will explode at its weakest point if the battery enters thermal runaway.
Thermal runaway can occur if the demands placed on a battery exceed the battery’s capabilities. The high current causes the battery to overheat. The high temperature accelerates the chemical reaction within the battery and reduces the cell’s impedance, causing the battery’s temperature to increase further. As the battery’s temperature continues to increase, the chemical reaction continues to speed up. The battery ultimately vents the excess pressure in the form of hot gas, flames and sparks. Thermal runaway ruins a battery permanently and can cause severe injury.
You can avoid thermal runaway by avoiding the two things that cause it: overheating and high current. Next, we’ll discuss the situations that can cause those problems.
A short circuit happens when electricity flows through the wrong path – a path with little or no electrical resistance. In a vaping device, a short circuit would cause the battery to release its full power almost instantly. Releasing so much power so quickly would cause the battery to overheat and enter thermal runaway. Thankfully, short circuit protection is one of the basic safety features of any good vaping device with regulated power. If a device detects a short circuit, it’ll display an error message.
A faulty atomizer coil is the most likely reason why a vaping device might have a short circuit. If any part of the coil touches any metal object other than the atomizer’s mounting posts, you’ll have a short. That can happen if you fail to trim the coil’s leads or build a coil that’s too large for the atomizer’s build deck. It can also happen if the coil is jostled loose from a mounting post. If you build your own coils, it’s a good idea to check your atomizer with a resistance meter before using any new coil.
The second most common reason for a short circuit in a vaping device is battery damage. If a battery’s wrapper is torn or missing, the metal on the side of the battery could touch the metal on the inside of the device. You should never use any battery with visible damage – even if the damage seems small.
Above, we mentioned the fact that thermal runaway can occur if the demands placed upon a battery are too great. With a short circuit, that can happen instantly – but it’s also possible to overheat a battery slowly during normal vaping with too high an amperage load. The amperage is a function of the resistance of the coil and the power used to drive the coil in watts or volts.
Many vaping devices with regulated power can tell you the amperage draw that your current coil and wattage setting will create. If your device doesn’t give you that information, you can use an Ohm’s law calculator to figure it out on your own. If your device has one battery, you’ll need to choose a coil and power setting that create an amperage draw well below the battery’s continuous discharge rating. If your device has two batteries in a parallel configuration, you’ll need to keep the amperage below the combined CDR of the two batteries. The good news is that maintaining a safe current with a power-regulated sub-ohm mod isn’t difficult. If the current is too high, the mod displays an error message.
So far, we’ve described potentially dangerous situations that should never occur with a modern power-regulated vaping device. The next two situations, though, can potentially happen with any device. The first of those is overcharging. A battery can potentially overheat and enter thermal runaway if it is charged at too high a rate or charged above its maximum voltage. If you charge your vaping device via a USB port, the device’s built-in charging circuitry should automatically stop charging the battery when it reaches its target voltage. Nevertheless, you should always be nearby when you charge your batteries in case something unexpected happens.
If you charge a device using something other than your computer’s USB port – such as a wall or car adapter – you should make sure that the charging adapter matches the specifications that your vaping device expects. Most mods require 0.5-amp or 1.0-amp chargers. Never charge a vaping device with a wall adapter for a smartphone or tablet. A charger for a mobile device typically uses a 2.1-amp current. The faster charging speed could potentially damage your battery or cause it to overheat.
Improper Battery Transport
One of the great things about having a mod with removable batteries is that you can easily swap in new batteries when the batteries that you’re using die. It might be tempting, therefore, to carry a pair of spare batteries in your pocket. That’s an extremely dangerous practice, though, because batteries can potentially touch each other – and other metal items such as keys and spare change – during transportation in a pocket. When you transport loose batteries outside your mod, carry the batteries in a plastic or silicone holder to prevent them from touching other metal objects.
Up to now, this article about sub-ohm vaping safety concerns has assumed that you own – or are considering buying – a power-regulated vaping device. What if you own a mechanical mod instead? Mechanical mods don’t have regulated power. They have no safety features at all, in fact – and that makes them a special case. When owners of regulated mods experience critical battery failures, it’s usually during charging or improper battery transport. If a mechanical mod experiences battery failure, though, it could potentially happen while the device is in use – and in front of the owner’s face. Because mechanical mods have so many potential safety issues – especially when used for sub-ohm vaping – they merit their own discussion.
A mechanical mod can’t detect a short circuit, high current, low voltage, high voltage, battery damage, overheating or any other problem that could lead to critical battery failure. It’s possible to avoid those problems, but you’ll be the one doing the work if you have a mechanical mod. It’s okay to forget a few safety precautions once in a while if you have a regulated mod. If you have a mechanical mod, though, you’ll need to do all of these things every time you use the device:
Check the resistance of your atomizer coil and test for a short circuit
Use Ohm’s law to confirm that your battery’s voltage and coil’s resistance won’t combine to produce an unsafe current
Replace your battery promptly when the vapor production decreases noticeably
Retire or rewrap your batteries when you notice damage
Use a hybrid mechanical mod only with a compatible tank or atomizer
Thousands of vapers around the world use mechanical mods every day without incidents. If you’re going to use a mechanical mod, though, you must understand that mechanical mods are for experts. Your device can’t look out for your safety, so you’ll need to monitor the device yourself. If you don’t have the time or patience to exercise proper battery safety consistently, you shouldn’t use a mechanical mod.