Parallel vs Series Unregulated Mechanical Box Mods | Vaping Battery Safety

Box Mods have been around for some time now. With many of these new vaping devices on the market comes an entirely new learning process in vaping battery safety.  If you want to get a dual-battery mechanical mod but aren’t confident on the difference between a parallel and series battery configuration, this article is for you.

While many vapers believe they understand the difference between an Unregulated Parallel and Unregulated Series box mod, the reality is that a substantial number of people using these devices do not understand the way that each of these circuits is actually connected. Not knowing can turn even simplest of mistakes into a potentially dangerous scenario.

You may be confident and think you understand Ohm’s Law and the limitations of your battery, but then you buy that shiny new unregulated mod and remember safety and think you need to do some more research, well you’ve found the right place to start.

Vape battery orientation is Crucial for Safety

When using an unregulated series or parallel box mod understanding the design of each of these devices and their battery orientation is crucial to your safety. There have been some stories in the press that accuse vaping products of exploding or catching fire when in reality they have been misused.

If your mod makes a hissing noise and you are not able to pull the batteries out soon enough, then it could end in disaster! If you are lucky, then you may get away with minimal damage, at best you’ll get cells hissing and releasing toxic gas, or worse catching fire or exploding. If this does happen to you or someone you know, the best way to check for incorrect orientation is to remember that the batteries used for vaping are built to vent at the top, or the positive end, so you will see where the damage is and know its in the wrong way round.

What Causes Battery Failure?

When a battery fails, venting occurs as it needs to release the toxic gas inside, when a battery vents it starts hissing. The cause of battery failure is usually the battery shorting from either damage to the battery, or user error.

A short circuit occurs when the positive and negative terminals of a battery are connected with a low resistance connection, causing a high current to flow and therefore the transfer of a large amount of energy in a short period.

As a vaper, we all need to learn that taking the time to make sure our batteries are facing in the correct direction (especially in unregulated devices) before you hit the fire button can prevent dangerous scenarios like a fire or explosion.

Series: Your batteries will be connected from positive to negative, linking the batteries together to increase the voltage of your battery supply.

Unregulated Series box mod using its batteries in series will stack the voltage applied to the coil generating current from each battery at the same time combining the voltage. The number of batteries multiplies the voltage, while the amp draw remains that of a single battery.

Series Dual Battery Box Mod Safety
Series Dual Battery Box Mod Safety

Parallel: Your batteries will be connected from positive to positive and negative to negative when you connect this way you double your amps.

Unregulated Parallel box mods split the current between two or more batteries at the same time. The total voltage remains that of a single battery, improving battery life while increasing the amps since there is less draw on each battery in the circuit.

Parallel Dual Battery Box Mod Safety
Parallel Dual Battery Box Mod Safety

Choosing the Right Battery

If you are an experienced vaper, then you’ll know that choice of battery matters. If you are new to vaping or looking to buy you first vaping kit, it might be tempting to focus on coils, wicks, and tanks, and miss out on one of the most crucial elements of any vaping setup.

When choosing a battery, you need to look for long life, excellent performance and above all safety, but also once you own them is to look after and keep them safe. Battery choice is limited and will depend on your setup. However, there are a few critical things to bear in mind when choosing and caring for a battery:

Check the Voltage and Temperature of Vape Batteries

When it comes to vaping, we are not only concerned about the capacity (how long it will last between charges) but also need to consider the current and voltage. A battery with a high capacity can’t have a high current. A high voltage battery will send more current through the coil, which is ideal for clouds and sub-ohm vaping. Even more important than current, voltage and capacity, is temperature.

The temperature of a battery when it’s being used or charged will determine its lifespan. Cheaper batteries will suffer from higher temperatures, aging them quicker and or raising the possibility for them to explode. Which could turn out to be more costly in the long run if it damages your kit or causes injury, so choose carefully by checking out our Best 18650 batteries.

Using Vape Batteries Safely

The most significant risk associated with vape batteries comes from sub-ohm vaping which typically draws a large current to produce bigger clouds, which shouldn’t be a problem if used correctly with the right batteries.

There are some simple rules when it comes to batteries; the most basic rule is never to exceed the amps of your battery. Never carry batteries in your pocket as they can short with each other or with keys and coins which will damage them permanently or they could start to leak.

Is There a Safe Way to Run Super Sub-Ohm Builds?

A lot of vapers ask the question “Is there a safe way to run my super sub-ohm builds?” Well, the answer isn’t a straightforward yes, more of a possibility. Its dependant on the Unregulated Parallel box you use, it could be safe to run lower ohm builds. The most important thing is to pay attention to the safety ratings for the device you have. If you are unsure, check online or with your local vape shop to find out what your device you have is capable of achieving.

For example, it would be entirely unsafe operating a 0.12-ohm coil in a tube mod you are drawing 35 amps, or if you are running a 0.12-ohm coil in a series box mod as you are drawing 70 amps. However, if you use the same 0.12-ohm coil on an Unregulated Parallel box mod, you are now only pulling 17.5 amps dividing the amp draw between the two batteries making this the safest option for a super sub-ohm build.

What are the problems with Unregulated Box Mods?

  • Wrong battery direction: Inserting the batteries into the device in the wrong direction causing them to short out and go into thermal runaway causing it to vent. The consequence of a battery venting could include device damage, batteries hissing and releasing toxic gas, to them catching fire or exploding
  • Low build resistance: Building dangerously low for a series box mod and not adjusting to compensate will cause a battery to go into thermal runaway causing it to vent. The consequence of a battery venting could include device damage, batteries hissing and releasing toxic gas, to them catching fire or exploding
  • Not regularly cleaning: Not cleaning your vaping device on a regular basis add to the risk of draining the batteries at different levels due to one contact being cleaner than the other which becomes much riskier and dangerous


Whether you use an Unregulated Series box mod or an Unregulated Parallel box mod the key to safety is to adjust your build to ensure you receive maximum output. Both devices are capable of putting out the same wattage and therefore the same power.

Always remember safety first! Whichever configuration you go with you should always use a new pair of batteries and never mix them with a different brand, age or capacity as that could end in disaster. If either one can’t keep up then, it could go into thermal runaway causing it to vent. The consequence of a battery venting could include device damage, batteries hissing and releasing toxic gas, to them catching fire or exploding.

Jules M
Jules M
Jules is our vaping font of knowledge. He has been a passionate vaping supporter since 2013 and spends his time trying to educate people with ‘facts’ on the safety and benefits of vaping.

Related Articles

Best Vapes

Learn More About Vaping