I have a noob question as well. Just ordered my first mods, two with VV. The tank carts I got are rated at 1.5 ohm, and are dual coil. So I guess what I'm unsure about is whether having dual coils will factor into the voltage question or if following the elementary expressions of Ohm's law is enough, taking the 1.5 ohm rating as the equivalent load impedance. The reason I ask is because I heard someone say that dual coils makes calculating the requisite voltage more complicated.
I have never used a dual coil cart but I think it's just two 3-ohm coils wired in parallel. You can use the ohm's law on the 1.5 ohm equivalent. But keep in mind that each coil is now only getting half the power you calculate. And half may not be enough to adequately vaporize the juice. So you have to crank up the voltage.
I found this out by wiring a dual coil into a Vivi Nova and had to crank up the provari to produce 14 watts! It went from very little vapor to nuclear throat hit very fast.