SERIES vs PARALLEL   What does it mean?  Which is right for you?

We sort of past the days where unregulated box mods were the craze as better and better regulated box mods are being released, but there is still quite a demand for the unregulated box mod, and there are a few things you should know to use these devices safely.  The biggest difference is the battery configuration, either in series or parallel.  ​But what is the difference between them?  Let me show you.

SERIES MODS

To have a mod with its batteries in series is generally what you’ll see in a variable wattage device.  You can identify these mods by the way that the batteries face when they are inserted into the mod.  If the two (or more) batteries face opposite directions, they are in series.

So what does that mean?  Well, this has serious implications in a mechanical or unregulated device.  If the batteries are in series, the device will push the combined voltage of the batteries to the atomizer, but the current rating and capacity will be that of one battery.

For example, if you have two Sony VTC4 18650s in your mod, both fully charged, the device will fire at 8.4 volts instead of 4.2 volts, have a safe continuous current discharge of 30 amps, and a capacity of 2,100 mAh. Adding a third battery in series would bring the voltage to 12.6 volts, with the same 2,100 mAh and 30 amp discharge, which is even more difficult to build for.
 
Series mechanical mods are sometimes more difficult to rebuild for than parallel mods, because they need coils that can withstand that high voltage without falling apart or breaking, while still not requiring more than 30 amps of current.  With the example above, you wouldn’t want to build below 0.3Ω to fire the device safely, but that would be firing at over 250 watts, far too much for most vapers.  Ideally, most would want a coil at around 1Ω for 70 watts.

PARALLEL MODS

Parallel mods are a completely different beast, and this configuration is used almost exclusively in unregulated devices.  You can identify parallel mods by looking again at the direction of the batteries.  If they’re all pointing in the same direction, you’ve got a parallel mod.

The reason why unregulated box mods tend to use a parallel configuration is because the voltage is still the same as one fully charged battery (in our case, 4.2 volts), but the capacity and continuous current discharge is stacked. 
In the example above using two Sony VTC4 18650s, the voltage output would be 4.2 volts, but with 4,200 mAh and 60 amps to play with.  Adding another battery would bring you to 6,300 mAh and 90 amps maximum discharge.
This means you could have a long lasting battery with super low resistance builds, running as low as 0.07Ω and still be within the continuous discharge rating of the batteries.

FOR REGULATED MODS

Most regulated box mods will use the series setup, and step-down the operating voltage to the proper voltage at the set wattage. This puts less stress on each battery than over-drawing voltage in a parallel setup, but there are some parallel regulated devices in the wild

Battery Configuration