What is the Difference ?

[m1ke]

I've looked a bit, but I know some of you guys can give a more simple yet detailed explanation of the differences between a single coil cartomizer and dual coil cartomizer.

For instance, does a 1.5 ohm dual coil cartomizer actually have the resistance of a 3.0 ohm cartomizer ? Are these safe to use with automatic batteries at around 3.7 volts ?

 

[Vapoor eyes er]

Here's the best explanation I've ever found that's understandable...
"A 1.5 Ohm dual coil is made up with two 3 ohm coils in parallel. So instead of one coil heated to around 9 watts (assuming voltage is 3.7), you get two coils at around 4.5 watts each. Total power is still around 9 watts, but with dualies that power is 'spread out' over twice the length of coil, it's also snipped in half and wired in parallel, so that's why it works more like two dimmer light bulbs than a single brighter light blub."

 

[Kanj.nguyen]

A 1.5 ohm dual coil cartomizer has the resistance of a 1.5 ohm cartomizer. The 1.5 is overall, not each coil.

As for its safety on an automatic 3.7: if the automatic is really a 3.7, you would be running at 9 watts, which is borderlining too hot, but not horrible. However, many automatics are branded 3.7 yet only give out 3.2 ~ 3.5

 

[thrillcaptain]

A single coil cartomizer has one resistor in its circuit, operating at the labeled resistance.

A dual coil cartomizer has two resistors wired in parallel. Because of parallel circuitry, the resistors do not impart their entire resistance to the circuit. (see formula for parallel resistance) In a two-resistor circuit, each resistor will impart half of their resistance to the circuit, meaning that each resistor in a 1.5ohm dual-coil cartomizer will be 3 ohms.

I have zero experience with automatic batteries, but I have used 1.5ohm dual coil cartomizers on an eGo battery which operates (usually) at 3.7V, and it is both safe and awesome.

Learn more about series v. parallel here:

Series and Parallel Resistor Circuit Calculations

Hope this helps...

 

[markfm]

On the safety aspect, for a single battery nominal 3.7V PV, the PV capacity (mAh) matters, as well as any PV protection circuitry.

Some PV may cut out at 2A, so a 1.5 ohm won't fire at all. No harm, it just won't work.

A larger battery PV (typically a 650 mAh or greater) is normally recommended for use with low resistance (personally, I'd use at least 900 mAh for 1.5 ohms, but that's just me). No harm, it'll work (unless the PV also has a low amp cutout).

Using a 1.5 ohm on a smaller cigalike battery, generally things down in the couple hundred mAh range, is generally not advised, since it represents a pretty significant current draw. Best case is just really cruddy run time. Potential harm.

 

[m1ke]

Thanks for the quick replies.