Batteries can be dangerous whether in your cell phone, laptop and especially in your vape mod.  Knowing what is safe and what is not can save you from injury, save you some money and can even provide you a better vape experience.

Vaping 101: Battery Safety



Big tobacco is out there trying to protect profits and scare the hell out of the citizenry to lead them to believe that vaping is more dangerous than smoking.  This is obviously corporate misinformation as we know for a fact that using a vape is far and away more safe than cigarettes or even smokeless tobacco.

But one of the easy wins and big scares the tobacco industry has going for them is battery failures.  We have all seen the videos of ecigs blowing up in some poor guys pocket or seen the aftermath of a tube mech exploding in some guys hand or face and causing some pretty serious burns.  These events are rare and easily avoidable!  

How do I know they are rare? In a country of 300+ million (USA only) we only hear news of it a few times a year and it always makes the nightly scare report on every channel. 

One thing that does seem to be common with all of these cases is a lack of knowledge about battery safety or doing something dangerous like keeping your spare batteries in your pocket, using unsafe gear or building coils at far too low ohms.

What the battery ratings mean

MAH and A

18650 batteries are far and away the most common battery used in vaping.  They are usually advertised by saying something like LG HE2 2500mah 20A (35A) 18650 battery.

Let's break that down a bit.  LG HE2 is the brand and model name of the battery respectively.

Mah stands for milliamp hours and is the rating for the strength or capacity of the cell in question.  The higher the number the longer the battery will last as there is more capacity for energy storage in the cell.  Lower the number shorter the life.

A is short hand for Amps as is the volume of electrons that can pass through per second. 

In the example listing above we see 20A but also (35A), what gives?  The 20A is what is called the continuous drain rating.  This is the rate that the battery can be continuously drained at and still remain in a safe operating temperature and condition.  

The second, higher rating is what is know as the pulse rating.  This is the rate that battery can be pulse at or used for a very short period of time without causing a problem.  

These pulse ratings should never been taken at face value as there is no standard way to measure them.  To stay safe you should always just go with the continuous drain rating of your battery.

cutaway image of a lithium ion battery

battery cutaway

The way a rechargeable battery is constructed, the plates inside provide a means for the amps and there is a gel that stores the electrons and provides the capacity (mAh rating).

Since there is a lack of space in the cell, there is a constant trade off going on.  All cells usually end up in one of three ways:  high capacity / low amps, lower capacity / high amps or a mixture of the two.  

If you see a battery with a super high mAh rating and a high amp rating, your BS detector alarms should be going off.

Picking the right battery

Get the battery based on the use

If you are going to be doing some low wattage higher ohm (resistance of the coil) vaping you would may not get the same battery you would get for higher wattage / lower ohm vaping.

Regulated Mods


When calculating the necessary amps to run regulated device we need to keep in mind that the resistance of the coils isn't important, the desired wattage is the important part.  On a regulated mod you can build your coils at any resistance that is in the firing range of your device.

A regulated mod doesn't power the coils directly, it powers the regulator which in turn heats the coils with some set (variable) wattage.  The wattage supplied by the device is equally divided over the number of batteries in the mod.  For example: to reach 100 watts on a two battery mod, each battery is effectively supplying 50w.

Mooch, an independent battery tester and expert, has supplied a pretty easy to remember formula for calculating max amps per battery for regulated mods over at ECF forums.

His formula is Max Amps Per Battery = (Max Wattage Per Battery / Minimum Voltage Per Battery) / 0.95.  (The .95 is to account for the inefficiency of the regulator.)  

He used a pretty good example that we will just reuse here for an example:

You have a two battery 150w regulated mod that has a minimum battery voltage of 6.4v or 3.2v per battery.  Each battery would have be able to handle 75 watts to get the 150w desired.

Max Amps per battery = (75 / 3.2) / 0.95   =  24.67A.  In other words, to run your device at 150w you need to have two batteries that are each rated at a minimum of 24.67A (25A) continuous drain.

Let's change that up a bit with a reverse example.  What if we are using the same 150w two battery mod, but have two 20A rated batteries and want to determine the max wattage we can safely vape (regardless of experience)? 

We have to rearrange the formula using some high school math to:  Max Wattage Per Battery = Max Amps Per Battery * 3.2 * 0.95  or Max Wattage per battery = 20 * 3.2 * 0.95 = 60.8 watts per battery or 121.6 total watts.  

What if we had a two 30A batteries what can we vape at? 30*3.2*0.95 = 91.2w per battery or 182.4w total.  This shows that if we have a two battery regulated box mod with the best 18650 batteries rated at 30A, we should only set our device for a max of 182w even if it can go up to 220w as is the case with the SMOK Alien.

What if instead of doing some high wattage vaping (likely with a low ohm build), we want to do some single coil, higher ohm / low wattage vaping?  Let's say we are using a single battery mod vaping at 12.5w. What kind of battery do we need?  (12.5/3.2)/0.95 = 4.12A ! Wow, that is not very high of a required Amp rating. 

We could pick a 10A high capacity (mAh) battery for that set up.  We would have a really long battery life and would still be safe as long as we didn't crank the wattage past 30. (10*3.2*0.95=30.4).  I would recommend getting the Samsung 30Q here. It is a 3000mah battery with a 15A manufacturer's rating but Mooch rated it at 20A.

Unregulated Mech Mods


battery configurations for single parallel and series mech mods

Battery configurations for 3 various mech mod types

Unregulated mods don't have the regulator (HA!), making the ohm measurement of the coil the important part of the required amp capacity calculation.  We need to use a formula known as Ohm's Law.  

Ohm's Law is Amps = Voltage / Resistance.  

As the battery is discharged, the battery will be outputting less amps so we will always plug in the max voltage of the cell into the equation.  

With 18650 batteries, the standard max voltage is 4.2v. We will use that voltage in our examples.

Unregulated Single Battery Mod

Let's say we have a single coil build in an RDA on a single battery tube mod that came out at .35 ohms.  Using Ohms Law, (4.2/.35) = 12A.  We will need a battery that can handle at least 12A.  We should add a safety buffer of 10%, making that 13.2A.  We could get a battery with a higher capacity quite easily that will handle this build.  The Samsung 30Q 15A 3000mah 18650 would be a good fit in this case as we saw with a regulated set up above.

What if we wanted to switch that around and find out what build we can use with our battery with the same build?  We would rearrange ohms law to (Voltage/Amps = Resistance).  Let's say we have a 20A/4.2V battery what build can we use?  I would add in a generous safety buffer of 3A (15%) and change that to 4.2V/17A.  (4.2/17) = .247 or .25ohm build for your RDA. 

Unregulated Parallel Mod

As you can see in the diagram above there are two different types of battery configurations available in two battery unregulated mods, parallel and series.

In parallel batter configurations, that positive terminals together as are the negative terminals. This type of wiring allows for the the over all voltage of the power cells to remain at 4.2V but on paper it doubles the amperage.  

In real life however the amperage basically increases by 50% due to resistance inserted due to the wires, battery sled and other factors. If your mod has two 20A batteries in parallel you now have a 30A cell. If you have two 30A batteries in parallel you now have 40A available to your mod.

Increasing the amperage of your mod makes lower ohm builds available to you which you can prove thanks to ohms law.  Let's say we now have two LG HG6 cells, which are 1500mah 30A each.  Using ohms law, with our 3A buffer, we can calculate (4.2/37) to get .113 ohms.  

I still would not build that low on a mech just due to the fact that ohm meters are only accurate to .01ohm at that level but I would feel safe with a .13 build.  

These precautions with low ohm builds may seem overly cautious but that is what makes me feel safe using these devices. I like having all my fingers and face intact.

Unregulated Series Mod

In a series mod you have a reverse configuration to that which we saw with parallel mods. The positive terminal is connected to the negative terminal of the next battery and vice versa.  This also creates exactly the reverse effect: the voltage doubles and the overall amperage stays the same.

In this setup a previously safe build on single mode would now be unsafe since as you can prove with ohms law.  Let's use that same 17A but this time the voltage is 8.4. (8.4/17) = 0.494ohm.  

That previous build we were using on single battery of .247ohm is now pulling (8.4/.247) is now pulling over 40A! That is super unsafe as we only have 17A available to us.

Editor's note: If you are a new(er) vape user we would recommend against getting one of the mechanical / unregulated mods.  Unregulated mods require a lot more knowledge than just the standard regulated mods / sub-ohm tank combo due to their lack of safety features.  We consider unregulated mods an advanced user only item.  Personally, we pretty much only use regulated mods these days for safety protections and the vape experience is customized!

Which Battery to get


Are brand name batteries worth the extra money? The short answer is yes.

Battery factories cost a fortune, millions and millions of dollars.  This pretty much means that only the huge names can afford all that research and development cost.  

These factories have their own internal standards and usually have three classes of ratings: A, B and C.  The A class rated batteries get the name brand packaging and the other batteries that didn't quite make the grade get sold on to other companies. These non-big brand name companies end up putting their own wrapper on these batteries and sell them to consumers, hence the  name 'rewrappers'.

The A class batteries may only perform a bit better than B class but the problem comes how the rewrappers advertise the batteries.  Some of these companies make extremely exaggerated claims about their cells such as enormously high capacity or advertise the unreliable pulse rating as the continuous drain rating.  Often the batteries aren't consistent with the rating even if it is beleivable.  This can obviously lead to an unsafe situation. 

This uncertainty leads us to recommend buying brand name batteries over any rewrapped ones.  

Some reliable manufacturers are:

  • LG
  • Sony
  • Samsung
  • Sanyo/Panasonic

Some 18650s batteries that are popular and well tested:

  • LG HB2 / HB4 / HB6 1500mAh 30A 
  • LG HE2 / HE4 2500mAh 20A 
  • LG HG2 3000mAh 20A (Brownies - these are very popular)
  • LG HD2 2000mAh 25A
  • Samsung 25R 2500mAh 20A
  • Samsung 30Q
  • Sony VTC5A - (VTC3/4/5 were all big hits but not in current production as far as I am aware)

Check out Mooch's independent test results for some detailed test result info complete with comparative graphs to do some research before you buy.

Catastrophic Battery Failure and What causes it

Venting and Thermal Runaway (Explosions)

There are some controlled venting and thermal runaway (fire/explosion) videos on Youtube displaying the serious degree to which everyone should handle batteries of all sorts not just when vaping but with car batteries etc.

Venting occurs when there is the battery has some sort of short or has been drained in excess of its continuous drain rating and the safety disk inside the 18650 snaps.  

After this occurs the internal pressure of the battery, from the electron capacitance material or liquid, is released in the form of gas or liquid through top vent holes of the battery that can be seen when looking at the positive terminal of an 18650 battery.

When the internal temperature starts to excel too fast for the safety disk to have any effect, thermal runaway occurs.  Once the temperature gets too hot the contents of the battery will ignite and begin to vent flame from the top as well as gas.  If the pressure is unable to escape from either the battery or more likely the mod, that is when some sort of explosion occurs.

Luckily venting is more common than thermal runaway, but steps should be taken to prevent both.

What is the trigger for battery venting / thermal runaway situations? Electrical shorts! These can be prevented with active precautions and with some preventative maintenance of your mod, tank (RDA or RTA/sub-ohm) and particularly your batteries.

Shorting the battery directly is the easiest to prevent. Some actions that cause batteries to short directly are:

  • Damaged wrapping or insulating ring allowing contact between your the battery housing and a or piece of metal which is easy inside of a metal mod. Two batteries with damaged wrappers can touch and also cause a short. These can be prevented by frequently inspecting your batteries for tears and when you find a torn wrapper or insulator, just replace the insulating ring and/or rewrap the battery.  This is a very easy job. 
  • Damaged, dented or deeply scratched battery housing can cause increased, unsafe pressure inside the battery or damage the internal properties and cause a serious problem. Don't use or recharge a damaged battery just safely dispose of it.
  • The battery shorting in the pocket due to direct contact between the positive pin and the side of the battery wall due to a piece of metal like a key or coin touching both.  This can be prevented by carrying your batteries in a battery case or silicone battery sleeves.
  • Hard Short in the atomizer - this is most common when the coils are improperly placed or secured inside the tank and touch some other metal in the tank besides the posts such as the chamber wall.  This can be preventing buy always building, assembling and testing the top on an ohm meter before placing on your mod.  
  • Another hard short can occur in the atomizer when there is a problem with the peak insulator in the atomizer itself either through degradation or melting. Always build on that ohm meter! If you can't figure out where the short is it is probably time to get a new topper.
  • The firing pin length is critical on atomizers when you are going to be using it on hybrid top cap mech mods where the pin comes in direct contact with the battery.  Inspect your tank and make sure the 510 is protruding and is not even close to being flush with the threading.  When in doubt, don't use that gear!
  • Placing the batteries in backwards can cause a short in most devices as well.  Regulated mods that have reverse polarity detection were invented for just this reason.  Always make sure you are placing your batteries in the correct direction.
  • Firing in the pocket on accident and exceeding safe operating temperatures.  Use the lock feature on your mod or remove the batteries and place them in a case before putting the mod in your pocket. A piece of metal jumping, such as a key, the RDA and side wall of a metal unregulated mod which causes it to fire. Take the batteries out and keep them in a carrying case.
  • Violating the design of the battery (exceeding continuous drain rating) by putting too low ohm build on an unregulated mod or by exceeding safe wattage on a regulated mod.  Consult the formulas in the above sections relevant to your device.
  • Batteries of differing amperage are used in the same device.  Since each battery must supply the same amount of power in a multiple battery mod as the other batteries, (ex. a 10A mixed in with a 30A in a high power situation or one worn out battery that discharges faster than the others)  You can marry your batteries to prevent this situation.  Marrying and clearly marking your batteries is to only use and charge those batteries as a set. You also don't break them are apart of used them alone or with other sets.

Charging your Batteries


Rechargeable batteries degrade over time even if they are just sitting there unused.  We can save a little bit of coin and get squeeze some extra life out of our power cells if we manage them correctly.

A few dos and don'ts to keep in mind when it comes to battery recharging:

  • Don't get the cheapest charger.  Cheap chargers are as bad as cheap batteries.  The cheapest chargers don't actually charge very well and will just keep trying to charge your batteries until unplugged which is bad.
  • Do Spend a few extra bucks to get a decent charger that has a control board in it.  These 'smart' chargers can tell you how much voltage your battery currently has as well as some level of overcharge protection.
  • Don't 'overcharge' your batteries - check on your charger frequently enough to take your batteries off the charger when they reach full capacity
  • Do consider charging them at the lowest setting when you can. Charging at 2A is 4x faster than the typical .5A but it also can exhaust the life of the cell faster due to the stress of the higher constant electron flow back into the battery.
  • Don't use your batteries at a higher load than they are rated to handle.
  • Do consider using your batteries at a 10% lower capacity than their rating to account for age of the cell and the inefficiencies of the device. This is safe battery usage but will also increase battery life by reducing stress on the battery.
  • Don't overdrain your batteries - Draining the battery until the mod stops working isn't a good idea since the unsafe zone is below 3.2v, which is the cutoff point for regulated mods but this doesn't account for battery sag, which will drain the battery below this point temporarily before slightly recovering to back above 3.2.
  • Do consider switching your batteries for a fresh set when the power of the device starts to wane at around 30% battery life remaining. This will prevent overdrain and will provide best vape experience.
  • Don't use the charging built in to the mod - (*unless it has a built in battery pack), particularly if it is two battery.  Most mods will cut off power when one cell reaches full regardless the state of the other battery.  That is bad news for the lifespan of your batteries and can lead to some uneven performance in your battery set.  What if you are trying to use pass through (using the mod while charging) and there is a problem? Always take the time to use an actual charger. If you have a mod with a built in battery pack just wait until it is fully charged before using or use a different device.

How you can tell when to replace your batteries

and how dispose of your old batteries

Your batteries if properly maintained can last longer than you would think and in some optimal cases will be just fine for years.  If used hard or abused they may only last a few months.

Here are some indicators on when you should replace your batteries:

  • If the battery is dropped and the housing becomes dented/damaged replace it.  If it is just damage to wrapping or insulator just replace those pieces.
  • When the mod doesn't perform like it used to when the batteries were new. In unregulated mods this would mean that it doesn't hit as hard and in regulated mods this would mean that the charge doesn't last as long with the same settings.
  • If your batteries start getting warmer than normal during usage or when charging.
  • If your battery no longer gets a full charge.
  • If your battery has vented or leaked fluid.

If you decide it is time to buy a new battery or set of batteries, they need to be recycled to be disposed of properly.

Most cities that have a recycling program will take rechargable batteries as well as large home improvement stores like Home Depot or Lowe's.  You can also try to see if your local vape has a recycling program.  

Put electrical tape on the ends of your batteries so they don't short on any stray metal the way to the drop off or after they have been placed in the box with the other old batteries.




Disclaimer: We are not engineers and the recommendations in this article are opinions.  Every individual should research each battery before purchase and use to guarantee their own safety. The safety guidelines are are what we use with our personal equipment. Every individual is responsible for their own vaping equipment and their own safety.  You should consult the manual for your device and follow the guidelines for safe discharge of batteries provided by the manufacturer / supplier.