Vaping Battery Safety Guide
Hardly a week goes by without an e-cigarette explosion story surfacing in the news. The constant onslaught of negative stories and dire warnings about a “wild west” industry is enough to make both vapers and smokers considering making the switch reconsider. Are e-cigarettes just bombs waiting to go off? Why are there so many e-cigarette explosions? How do you minimize the chance of explosions with mods? Here is a guide to staying safe with your batteries, which also covers the crucial topic of Ohm’s Law.
- All lithium-based batteries carry risks, particularly due to something called “thermal runaway.”
- Most e-cig battery explosions occur during charging, but some happen when the device is in use.
- In use, explosions can occur when you try to pull too much current from your battery.
- Every battery has a maximum amount of current it can provide. You should ensure that the current you’re asking your battery for (given by current = voltage / resistance) is within this limit.
- Never leave your battery charging unattended, and avoid charging it overnight.
- Ideally, use the manufacturer’s charger for your e-cig, but if not, ensure the output power rating of the charger matches the input required by your device.
- Keep batteries away from flame and heat, don’t carry them in pockets with metallic objects, don’t stack batteries, ensure your mod has physical vent holes for safety, turn off your device when you’re carrying it and ensure you pair your batteries (always charged and discharged together) for dual-battery devices.
What Causes E-Cigarette Explosions?
The immediate question you may have when you hear about exploding e-cigarettes is: why do so many e-cigarettes explode? The question, though, is a little misleading. The main reason e-cigarettes explode is the same as the reason cell phones, laptops, and other electronic devices explode in rare cases: lithium batteries carry inherent risks.
The biggest risk of lithium batteries is called “thermal runaway.” This is a feedback loop, where excessive heat causes instability in the membranes that separate the positive and negative poles of the battery and leads to a huge current flow, in turn creating more heat and spreading the problem elsewhere. This situation then continues out of control, leading to venting of hot gas (possibly with flames), and if there’s nowhere for the gas to escape, it can lead to an explosion.
It’s worth stressing again that this can happen with any lithium ion battery, including most consumer electronic devices. Lithium-cobalt batteries become unstable at 302 °F (150 °C), and safer chemistry lithium-manganese options (like the AW IMR batteries) become unstable at 482 °F (250 °C). These events don’t happen very often, but there is a still a risk.
In most cases of e-cigarette battery explosions, the problems occur during charging. If you use the wrong type of charger or leave it charging for too long, it can lead to instability and thermal runaways.
In some more rare cases, the problems occur in use, which may be due to overcharging, or could be a result of vapers asking for more current than the battery can safely provide. In these cases, knowledge of Ohm’s Law and how it applies to battery safety helps you stay safe.
Volts, Amps, Ohms and Watts: An Ohm’s Law Primer
Most vapers encounter the terms volts, amps, ohms, and watts, but even though some – like voltage – are generally understood by most people, an analogy helps to clarify the basics.
Imagine a long pipe running down a hill. If you pour some water in at the end, gravity will pull it down the pipe and out of the other end. If the hill is steeper, the water will flow more quickly, but if it’s a gentler incline the water will flow more slowly. This is an analogy for voltage (measured in volts) and current (measured in amps): the steeper hill is like a higher voltage (and a smaller incline is a smaller voltage), and the amount of water passing a certain point each second is like the current. This means a higher voltage generally leads to a higher current.
Resistance (measured in ohms) fits into this analogy as the friction between the inside of the pipe and the water, working to slow down the current. So if you increase the friction at the same incline, the current will reduce, and if you decrease it, the current will increase.
Wattage doesn’t fit very neatly into this analogy, but since it can often be adjusted directly on e-cigarettes, it’s worth addressing. The basic definition of wattage is the amount of energy delivered per second. For the analogy, it can be thought of as the energy carried past a certain point by the flow of water each second – the energy that would be picked up by a water wheel, for example.
Ohm’s Law for Vaping
The relationships between voltage, current, and resistance explained by the above analogy demonstrate Ohm’s Law in basic form. The mathematical description is pretty simple, though:
Current = voltage / resistance
In words, this says that the resulting current is the voltage applied divided by the resistance. For vaping, the voltage setting you use and the resistance of your coil tells you how many amps you’re asking for from your battery.
There are many Ohm’s Law calculators that allow you to work out the current for your setup, but the math is easy to do in simple situations. For example, if you apply 3.6 V to a 1.8-ohm coil, the equation tells you that current = 3.6 V / 1.8 ohm = 2 amps.
The rule can also be extended to bring watts into the picture. The wattage you’re vaping at is given by:
Power (in watts) = (voltage × voltage) / resistance = voltage ^2 / resistance
So for the above example, this would give: power = (3.6 × 3.6) / 1.8 = 7.2 watts.
There are many other ways to work out each element of Ohm’s Law, which are often shown in formula wheels. For example, if you want to know the current produced by a certain amount of watts applied to a coil, you divide the wattage by the resistance of the coil and then take the square root of the result.
Battery Safety and Ohm’s Law
So why does Ohm’s Law matter for battery safety? The basic reason is that a specific battery can only provide so much current, and if you go over this limit, you may push the battery too far and experience venting or explosions.
The amount of current your battery can supply depends on its maximum continuous amp limit. Note the “continuous” part of that: there is also a “pulse” rating for a battery, which is always higher, but isn’t really relevant to vaping.
In some cases, instead of a specific amount of amps, you’ll find a “C rating” for the battery. You can use this alongside the capacity of the battery (the “mAh” number) to work out the maximum continuous current.
Simply multiply the mAh number by the C-rating, then divide the result by 1000 to get the maximum continuous amp limit. For example, the 1600 mAh AW IMR 18650 battery has a rating of 15 C. To work out the maximum discharge rate, multiply 1600 (mAh) by 15 (C) to get 24,000 mA, and divide by 1,000 to get the limit of 24 A.
So, to stay safe when you’re vaping, you need to know the maximum continuous amp limit of your battery and the amount of current you’re pulling from it. The simplest way to stay safe is to ensure you use high amp limit batteries, with maximum continuous discharge ratings of 20 A or higher, which will keep you safe unless you’re planning on doing some serious cloud chasing.
In many cases, regulated (variable voltage and/or variable wattage) e-cigarettes will have a maximum amp limit coded into them as a safety measure, so as long as you’re using a good battery, the device will stop you from exceeding its capability. Unregulated (mechanical) mods don’t have such safety features, though, so it’s vital to know how much current you’re asking for and how much your battery can provide. You should also leave a safety margin – don’t take your battery right up to its amp limit.
Safe Battery Charging
Knowing about Ohm’s Law helps you stay safe when it comes to battery amp limits, but as we mentioned earlier, many problems occur as a result of charging. Additionally, it’s ordinarily pen-sized, eGo-style e-cigarettes that explode, not mods. This primarily comes down to two things: charger compatibility and overcharging.
Overcharging is the simplest issue to solve: although devices should stop charging when they’re fully powered up, this often isn’t the case. The solution is to remove your device from the charger when it’s fully powered up. If you don’t leave your device charging unattended – which you shouldn’t do anyway – and don’t leave it charging overnight, you can easily remove it from the power when it’s fully charged. Plus, if your battery starts to get hot or other problems develop during charging, you’ll be there (and awake) to deal with it.
Compatibility is a bit more complicated, but the easiest solution is to only use the charger from the manufacturer. This isn’t strictly necessary, though, because as long as the threading is right (most e-cigs have 510 threading, so this won’t usually be an issue) and the power ratings are the same, then you can use other chargers.
The most important thing is to ensure the output voltage is right – for most chargers, it will be 5 V, but it’s crucial that this output matches the required input for your device (or that of the original manufacturer’s charger). Additionally, the output from the outlet you’re plugging the charger into should match the input required by the charger.
The current output is less important, since your e-cig will only draw the current it needs, but too high an output current on your charger can stress your device over time, and too low an output will drastically increase your charging time.
The safest approach is to use the original charger, and if that’s not possible, to use a charger with matching power ratings.
Other Battery Safety Tips
There are a few other points that can help ensure you stay safe with your e-cig battery:
- Keep your battery away from sources of heat, direct sunlight or flames.
- Don’t carry loose batteries in the same pocket with metallic objects such as keys or coins – this could create a short circuit.
- Always lock or turn off your device when you’re carrying it around.
- If you’re using a mod with two batteries, “marry” them. Buy them together, discharge them together and charge them together. The aim is to ensure that both batteries are roughly the same and one won’t be taking more strain than the other.
- Don’t stack batteries for a higher voltage: regulated, high power mods are safer than stacking batteries.
- Ensure your device has physical holes to allow has to vent if there is a problem, otherwise, a tube mod can turn into a pipe bomb.
Conclusion – Be Informed and Vape Safely
The tips in this article should ensure you stay safe when you’re vaping, but the most important lesson is to not take battery safety lightly. As long as you exercise some caution when you’re vaping and think about how to maximize the safety of what you’re doing, you’re very unlikely to have any problems. Vapers shouldn’t be worried about explosions – they really are rare, when you consider the number of vapers – but we also shouldn’t ignore the possibility entirely and be careless.
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