Thank's for your reply Envi, my coils are around 1.7 ohms and I'm vaping on a Ego battery, so it would be about 7 watts or even less. No point in asking if it's too low I suppose but at least is something to work with.
Sorry for leading to another point, but do you know where can I find more info about liquid going darker when vaping at lower voltages?
I can't remember where on ECF I gathered those tidbits. I think one indication might have been on this thread (actually took the time to read the whole darn thing, eek), or perhaps one of the other 3 or 4 other big threads I read on wire/mesh/watts/etc...
This is what I can say from my own personal experience.
I started with a 3/4 wrap of 32 kanthal (was waiting on more wire) which was a 1.5 ohm coil on a slightly less than 2mm wick of #500. I couldn't get it past 3.5v (8 watts) or I started to get hotspots on the top coil. I liked 8 watts on cartos, but I liked 10-12 watts on my dripping atties, so was trying to bump it up. While in this configuration, my juice would darken and I wasn't getting great flavor, but the vapor was ok.
Somewhere between that and getting my 30 guage wire, I read some posts about darkening juice, and the effects of just boiling your juice. You vaporize only part of the juice, so you get some vapor, maybe even good vapor, but flavor lacks and juice darkens from the buildup of the unvaporized components burning on the coil (and was I getting carbon buildup fast on some juices).
So it kinda hit me, I needed to get it hotter, but still couldn't with 32 on the 500. As soon as my 30 showed up, I did a 4/5 wrap (1.2 ohms) and I had that sucker at 13 watts (4 volts) in no time with no hotspot issues. The vapor was improved, but most notably was the fact that flavor bursted out from all my juices. No more carbon buildup from just one tank, juice isn't getting darker anymore, and I finally have a stable setup from which to keep experimenting from.
If I can find the original posts I read, I'll PM them to you. Hope my own experience helps not that it is any indication that is what is happening to you, just something to try and rule out.