My experience with TC is it can be fickle, especially how you wrap your coils. Contact coils like basic micro-coils (wire touches at each wrap) this can throw TC readings off as TC coils are inherently hotter and ramp up in heat quicker due to each wrap helps heat the adjacent wraps. TC coils work best when spaced with gaps between each wrap, this widens out the surface area, and each wrap is reliant upon generating its own heat, making the TC even along the whole wire, increasing TC accuracy. FYI, Evolv with the advent of the original DNA40 chipsets, and what started the TC movement, it was originally designed for Nickel Ni200, Titanium Ti1 came into effect later as vapers began experimenting given Ni200's low melting point, Ti1 for the most part only becomes dangerous if you dry burn it and cause titanium-dioxide to be formed, both wires should never be dry burned, most cases dry wicking still has some liquid in it unless you burn it dry and charcoal it, Ni200 should not melt nor Ti1 should not create titanium-dioxide with a previously wet wicking, the TC should ramp down due to the drying out wicking.
The most accurate control boards for TC, JMHO, are Evolv (DNA), Yihi (SX), Smoant's, and Hohmtech's, most others are cheap slap together and have very minimal TC control (example Kanger, set into TC mode the PCB sets watts to max and only allows you to set the TC cap, you have to adjust both the watts (with Yihi it is Joules when in TC mode) and the TC cap to fine tune the vape.
Single battery vs multi-battery for TC, unless you are needing super high watts, 55watts or higher when not in TC mode, then a dual battery mod comes into play, but on a dual coil, properly wrapped TC spaced coil, with maybe 26awg wire thickest for SS or Ti1, 28 to 30awg thickest for Ni200 (due to it has negligible resistance to begin with), 50watts should suffice for a proper TC setup, and it is a PITA to experiment what settings work the best for you as not only do you deal with the watts but the TC cap as well, took me about a week to get my TC setups down pat for my personal tastes.
TC, in most regards will seem anemic to standard wattage only mode, thus reason why most say TC is carppy and don't like it, myself it is a cooler relaxing no worries about dry hits or generating poisonous by-products type of vape.
I'd look at maybe purchase of a DNA75 (most times this will be a single battery device), I have 2, both HCigar Vt75's that use a 26650 though does have an adapter for using 18650's, and suggest at least a 25amp 18650 if you go the 18650 route, but the DNA75 is just as accurate as the DNA166/200's in my experience thus far.
