I know the basics of mechanicals but I'm wondering, for different resistances on rebuildables, do I need different batteries that push out different voltages? What's the deal with low resistance and sub ohm rebuildables with a mechanical? How do I choose the right voltage for my build?
One of the advantages of mechanical mods is that you don't have to worry about voltage other than being sure to recharge the battery once you notice the vapor production dropping down so you don't go below ~3.3 volts which could damage the battery.
The high-drain batteries suitable for vaping all have a nominal voltage of 3.7 volts and a maximum charge voltage of 4.2 volts. What this means is that the battery will be at 4.2 volts right off the charger, drop down fairly quickly to 3.7 volts, then "plateau" at 3.7 volts and slowly discharge below that.
You adjust the wattage (power) by altering the resistance of the atomizer.
Power is calculated by:
Watts = (Voltage x Voltage) / Resistance in ohms
So a 1.0 ohm coil will produce 17.64 watts with a fresh battery.
(4.2V x 4.2V) / 1.0 ohms = 17.64 watts
You also need to be aware of how much current (amps) your coil is pulling from the battery, and make sure that the battery can safely handle it. For safety reasons, I like to never go above one-half of a battery's maximum current rating.
Amps are calculated by:
Amps = Voltage / Resistance in ohms
That same 1.0 ohm coil will pull 4.2 amps from a freshly charged battery.
4.2V / 1.0 ohms = 4.2 amps
This would be safe for a 10 amp battery, since it is less than 50% of its rating (5 amps).
I use Sony batteries which are rated for 30 amps, so I always stay below 15 amps for my coils. This means that the lowest resistance I will use is 0.3 ohms.
4.2V / 0.3 ohms = 14 amps
In reality, however, I have found my "sweet spot" to be around 0.8 ohms, and I rarely stray from this unless I want to try something new.
Some people like to push their batteries harder, but I would not recommend this. When a battery with a huge amount of stored energy is used merely a couple of inches from your face, it is smart to stay well within the safety margin.
As per advice and guides on building coils, there are plenty of information in the
Rebuildable Atomizer Systems forum. There are also numerous videos on Youtube that show you step-by-step how to build every type of coil out there.
If you are going with an RDA (dripper) on your mechanical mod, and are using a battery rated for at least 10 amps, I would recommend starting out with a single 1/16" microcoil with 28 gauge Kanthal wire and a cotton wick at around 1.0 ohms. You will probably need around 7 or 8 wraps for this, but I am not certain because I have switched to a 3/64" drill bit to build my coils and have not built a 1/16" coil in a while. Also, depending on how tightly you wrap the wire, and how long the coil "legs" (the little bit of straight wire between the atomizer's posts and the coil itself), you may need 1 or 2 more (or less) wraps than what someone else does to reach the same target resistance. The 7 or 8 wraps is just a starting point -- build one, mount it, and check the resistance, then build another coil with more or fewer wraps based on what the first coil meters at.
Microcoils are probably the easiest type of coil to make, and wicking them with cotton is also extremely easy (and absurdly cheap -- a single bag of cotton balls will give you enough wicks literally for the rest of your life). An Igo-W is a great RDA because it is inexpensive, well-built, is easy to mount coils on (holes in the posts mean you just stick the coil leads through the holes then tighten the screws....no wrapping the leads underneath the screw head needed), and allows both single-coil and dual-coil builds.
Any specific questions on building your first coil should be asked in the
Rebuildable Atomizer Systems forum.
