Battery Safety: The Truth Behind Exploding E-Cigs & How to Vape Safe

Electronic Cigarette Battery Safety

The media love to print scary stories about electronic cigarettes.

For a couple of years we were always hearing that they were as dangerous as smoking, or contained fifteen times the level of carcinogenic chemicals, or would give you the dreaded popcorn lung.

These stories still pop up every so often, but there’s a serious problem with them all; they’re total nonsense.

That didn’t matter three or four years ago because the science wasn’t clear.

But since Public Health England reported that e-cigs are at least 95% safer than old-fashioned tobacco ones, articles like that are getting challenged a lot more vigorously.

Now the media has found something else to focus on, and it does have at least a grain of truth in it.

The new Big Thing in anti-vaping news is explosions, usually accompanied by photographs of alarming burns.

Some stories even have videos of an e-cigarette going off like a firework, which can be quite dramatic. There’s no doubt that explosions can happen.

Is this a serious problem, though? Is it actually a reason to be wary of vaping?

No, it isn’t.

And we’ll explain by going over:




First, it helps to know exactly what’s happening here.

It won’t surprise you to learn that the media are wrong as usual. Electronic cigarettes themselves can’t explode. What can explode is the battery.

There are different kinds of battery, but they all follow the same basic principle. Inside a battery are electrodes and a mixture of chemicals called electrolytes.

Charging the battery by feeding electricity causes changes in the chemicals; usually this involves charged particles called ions moving to one of the electrodes.

When the battery is put into a circuit the ions move to the other electrode, and in the process they release electricity into the circuit.

Some kinds of battery can be recharged when they’re drained, while others are disposable; rechargeable ones cost more to buy but save a lot of money in the long run, because the electricity needed to recharge them costs pennies.

Some types of battery are much more efficient at storing energy than others – engineers say they have a higher energy density.

This is why an alkaline AA battery like a Duracell lasts much longer than a zinc-carbon battery the same size; it’s much more efficient.

The problem is that even an alkaline battery won’t last long in an e-cigarette.

E-cigs use a lot of power, and they also draw a high current. That really beats up standard batteries.

The amount of electricity a battery can store is measured in milliamp hours, or mAh. The more mAh it stores the longer it will last.

A Duracell AA battery delivering a current of 0.1A will give you a total of about 2,350mAh of electricity.

The problem is that if you increase the current to 0.5A that falls by more than half, and at 1A it’s halved again – to about 500mAh.

E-cigarette makers recommend that modern box mods are used with batteries that can deliver at least 20A.

At that kind of current you won’t get much power out of an alkaline battery – in fact you’ll drain it in a few minutes.

Luckily there’s a solution.

Lithium ion batteries. They have a high energy density and can deliver it at high currents.

An 18650 battery is slightly larger than an AA and holds about the same amount of energy, but it can supply much more current.

A Sony VTC5 has a capacity of 2,600mAh and can pump that out at up to 30A. A pair of them will easily run a high-powered box mod all day.

There’s even better news too; unlike alkaline batteries lithium ion ones can be recharged around 300 times, and they don’t need to be fully drained between charges.

Less luckily, lithium ion batteries can explode in certain circumstances. Their electrolyte is a liquid solution of lithium ions, and if that gets hot enough it can boil. When it does, the pressure will blow the battery apart.

Unfortunately the liquid is also flammable, and if the battery bursts the combination of heat and air means it usually catches fire.

The electrolyte burns fiercely enough to cause injuries or set fire to anything it comes in contact with.




Calm down.

Lithium ion batteries are actually pretty safe.

Almost all modern electronic gadgets use them. Your phone, tablet and iPod are all powered by them.

If you take apart the battery pack from a laptop you’ll find anywhere from eight to twelve 18650s inside. (Don’t do this – it’s not very safe).

Electric cars run on lithium ion batteries, and if you have solar panels you can now buy a Tesla Powerwall to store energy and use it overnight.

There are billions of lithium ion batteries in use around the world, and if they were really dangerous most of the planet would be on fire.

Of course anything can fail.

Manufacturing problems can make a battery overheat, although that’s rare.

New batteries are usually charged at the factory, and if a fault was going to cause problems it would probably show up then.

It’s not very likely that your e-cig battery will suddenly catch fire for no obvious reason.

So why is there a story about an exploding e-cigarette in the media every few weeks?

Basically that’s because people are a lot less reliable than lithium ion batteries. By far the most common cause of battery explosions is user error.




As most of us learned at school energy comes in different forms. A battery stores electrical energy by converting it to chemical energy.

When the battery’s put into a circuit, chemical reactions inside turn in back into electrical energy and feed it into the circuit.

The circuit then turns it into some other form of energy – the coil of your e-cigarette converts it to heat, for example.

Your phone generates light from the screen, and kinetic energy in the speaker to create sound.

The thing about energy, however, is that in the end it usually turns into heat.

The light from a bulb heats up everything it hits – usually not enough to notice, but it’s happening.

The sound from your speakers is absorbed by the walls, making them vibrate slightly, and causing friction that generates heat.

If a battery releases its energy in an uncontrolled way, instead of feeding it into a circuit, most of it is released as heat. If there’s enough to boil the electrolyte you get an explosion.




One way to trigger an uncontrolled energy dump from a battery is to charge it the wrong way.

If you look at news stories about exploding e-cigarettes you’ll see that a lot of them involve an eGo-style vape pen that caught fire while it was being charged.

These devices have a steel case that contains the fire button, some circuitry and a small Li-Ion battery.

One end has the connector where you screw on the atomizer, and the other has a light metal cap.

If the battery goes critical the cap usually blows off, and the device can turn into a small rocket.

It’s often pretty dramatic, with a jet of flame erupting from the open end. It can also start a serious house fire very easily.

There are a couple of likely causes of charging fires.

One is pumping too much current into the battery. This upsets the chemical reactions inside, and they can suddenly go into reverse – dumping all the energy that’s been stored.

This is one reason why you need to use the correct charger for your batteries.

Most e-cigs with built in batteries use a USB charger, and it’s not hard to put too much power into these. One easy way is to plug it into your iPad charger, for example.

Pen-type batteries have a maximum charging current of 1A. If you’re charging it from a USB port on your computer it might only get 0.5A, so it will take longer to charge.

But although an iPad charger has a normal USB port and you can plug a standard cable into it, it delivers 2A.

The battery can’t handle that much, so there’s a serious risk of a fire unless the protection circuits are good enough.

If your e-cig kit didn’t come with a wall plug to connect the charger to, it’s safest to charge it from a computer’s USB port. Otherwise use a standard wall plug and make sure it’s not putting out more than 1A.

Another risk is over-charging.

If you put too much energy into a battery, eventually the chemistry becomes unstable and it can dump its charge. To avoid that, e-cigarette charging systems have protection circuitry.

When the battery’s fully charged the circuit either turns off or switches to trickle charging, delivering just enough power to keep it topped up.

But while eGo-type batteries may all look pretty much the same, some types have the protection circuitry in the battery itself and others have it in the charger.

If you mix and match parts you might find yourself charging an unprotected battery with an unprotected charger.

The next thing you’re likely to find yourself doing is standing in the street watching your house burn down.

If you have a kit and your charger breaks, it’s very important to get a replacement from the same manufacturer as your batteries.

That way you know they’re designed to work together and shouldn’t cause any problems.

Also beware of cheap kits from market stalls.

These might be put together from incompatible parts, usually because whoever’s assembling the kits doesn’t really know what they’re doing and just orders parts from whichever factory is selling them cheapest.

Because they all fit together it sometimes doesn’t occur to people that this might not be all that safe.

It’s best to avoid any kit that doesn’t come in a sealed pack with a recognizable brand name on it.

If it’s in a zip-up pouch there’s a risk the battery and charger haven’t been designed to work together.

Finally, some websites sell kits containing a mod, removable batteries for it and a charger.

Unless the charger is a reputably branded model that’s also sold separately, we’d highly recommend that you don’t use it.

Instead, throw it out and get a decent one from a brand like XTAR or Nitecore. They don’t cost a lot and they’re extremely safe.




Problems with replaceable batteries are usually caused by a short circuit.

Shorts happen when power flows out one terminal of the battery, through a circuit that doesn’t contain anything which will use it, then back in the other terminal.

In simple terms, the battery is feeding power into itself – and batteries don’t like that. A short circuit is a very reliable way to cause a battery explosion.

It can happen extremely quickly – within seconds of the battery shorting.

If current is flowing from your battery through your mod’s circuitry and the coil, there’s no risk of a short.

Modern devices have built-in short circuit protection that shuts everything down if it detects a potential problem.

If there’s another way for power to flow between the battery’s terminals, however, things can go wrong very quickly.

The first step to avoiding shorts is to look after your batteries. A standard cylindrical battery like an 18650 has two terminals – positive and negative.

Looking at one, you’d probably assume that the positive terminal is the stud or plate at the top, and the negative is the flat plate at the bottom.

You’re right about the positive terminal. On the other hand, you’re very wrong about the negative terminal. The entire metal case of the battery is the negative terminal.

It’s an open-topped cylinder and the whole thing is the terminal.

Once the electrodes and electrolyte have been put in, the open top is plugged with an insulated ring; the positive terminal is at the center of that, and the insulator stops power flowing between them.




So the plastic wrap on the battery isn’t just there to look good. It also insulates most of the case, with just the base left uncovered.

If the wrap gets damaged, however, shorts can occur.

If your mod has bare metal inside the battery compartment, and the battery’s wrapping is damaged, there’s potential for current to flow from the battery case straight into the side of the compartment.

Depending on how your mod’s wired up, that can cause a short.

Check your batteries regularly to make sure they aren’t damaged – and if you drop one, examine it right away. Any tears or scratches in the wrap are a potential problem.

If the metal case itself is damaged, dispose of the battery; it’s not safe to use it. If it’s just the wrap there’s a solution – buy some heat-shrink battery sleeves.

These come in various sizes and 18650 ones are easy to get. Put one over the damaged wrap, shrink it with a hair dryer and the battery is safely insulated again.

Even better, put them on all your batteries right away to give them some extra protection.




A few spectacular accidents have also been caused by mechanical mods. These don’t have any electronics in them; the metal case just forms a simple circuit.

Unfortunately, if you haven’t coiled your atomizer properly and the coil resistance is too low there’s a strong chance of a short circuit.

If you don’t know exactly what you’re doing, steer clear of mechanical mods.

There’s no real need to bother with them now anyway; you’ll get much better performance from a good box mod.

Even if you do know exactly what you’re doing, never use a modern atomizer with a fixed center pin on a hybrid mech mod.

A hybrid is a connector that lets the atomizer’s center pin rest directly on the top of the battery.

Some people like them because there’s almost no voltage drop and you can have a smaller, neater-looking device, but they can also be very dangerous.

Hybrids are quite old technology, and they were designed to work with atomizers that have an adjustable center pin that projects out the bottom of the connector.

That way, the center pin can touch the battery’s positive terminal while the 510 connector around it – which is the atomizer’s negative contact – is safely clear.

Modern box mods have spring-loaded center pins, though, so there’s no point adding the extra complexity of an adjustable one on the tank.

That means tanks now have a flat, fixed pin that’s pretty much flush with the connector.

Screw it to a hybrid and there’s a good chance the pin and connector will be touching the battery.

If that happens, as soon as you press the fire button the current will take the path of least resistance.

Instead of going through the coil it will flow straight down the mod’s case and into the negative terminal of the battery, instantly shorting it.

And because a mech mod is basically a metal tube with solid end caps, that leaves you holding a pipe bomb.




Finally, let’s look at the most common cause of battery explosions – carrying them loose in your bag or pocket.

This applies to any e-cig battery, but especially removable ones like 18650s.

There have been several incidents where people have done this, and it has resulted in some serious injuries.

Pockets and handbags tend to contain metal things, like coins and keys. If you put a battery in there as well you’re in serious danger.

If a piece of metal bridges the gap between the positive and negative terminals – and remember, that’s the whole metal case – the battery will short.

Even if the wrap is intact when it goes into your pocket, there’s no guarantee it will stay that way when it’s rubbing against the edge of a coin.

It’s even possible for a drop of water to cause a short. And if a fully charged 18650 cooks off in the pocket of your jeans you’re going to get badly hurt.

Never carry loose batteries with you.

If you’re taking spares with you – which is sensible – store them in a proper battery box or silicone sleeves. That will prevent any risk of a short circuit.

Basically, as long as you’re sensible with your e-cigarette batteries, the chances of having any problems with them are extremely minimal.

Every battery accident I’ve ever heard about was caused by one of the mistakes we’ve looked at here – not one involved a battery that just spontaneously blew up.

I’ve owned dozens of batteries.

Some have been used until they started to fade, then honorably retired; another bunch are still in daily use.

None of them have ever done so much as get a bit hot.

Meanwhile, cigarettes start dozens of house fires every month and are the biggest cause of fire-related deaths in the UK.

If you’ve been considering switching to vaping, but the thought of battery explosions was putting you off, you can relax.

As long as you use the right charger and follow some simple precautions, nothing’s going to go wrong.

If you’d like more information on battery safety, or if you’d like to know which batteries are best to buy, we highly recommend checking out Mooch’s facebook page.

Mooch is an authority when it comes to battery safety and testing.

He’s also posted some helpful battery safety articles on vaping360’s website. These articles provide good technical detail as to what it is that affects how safe batteries are to use.

He does a lot of battery testing to help you know which batteries are safe as well as which ones perform better than others.

Do you think the Media is helping or scaremongering by posting these stories? Let us know your thoughts in the comments…

Check out this Battery Safety video by Suck My Mod

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