Hi,
I just purchased a Wotofo Serpent smm and I like it very much. My build worked fine, I used the fused clapton coil provided in the package and everything worked just fine.
However, initially my mod (Smok Alien TC) read .194 ohms and I vaped on it for an hour or two and when I unscrewed the tank and screwed it back on, the mod read .271 ohms and I only get dry hits even though the tank was filled enough and i was only vaping on 65W?
Note: It changed from its newly installed resistance (.174) to .271 but now when I unscrew the tank and screw it back on it stays around .271 ohms.
Is it normal for it to change that much so fast? Or it is because the first time is wasn't vaped on yet? Also, isn't it supposed to do the opposite of giving dry hits?
Thanks in advance!
If you installed and wicked the coil yourself, noticed in a later post you said it is Kanthal A1, if you didn't dry fire and pulse the coil prior to wicking to check even heating along the coil/coils after install to check for hot spots and uneven heating, you'd run into issues. Kanthal is notorious after a fresh install of expanding and shifting when first firing. Also all metals when first fired will create an oxidation layer on the surface of the wire, this is the wire itself creating a protective layer around itself, with Kanthal this layer is carbon. This layer also insulates the rest of the wire from contact with other parts of the wire, thus when bare metal to bare metal contact broken and insulated by that layer the true resistance of the coil is now being read. Also the heat of the first firing has softened and annealed the metal into position and should not shift or move anymore unless the contact screws come loosened.
The dry hits could have been caused by a hot spot (a section of wire that gets hotter than the other sections), this extra heat will become dry faster than the other sections. Also if the coil expanded a bit, that could have been enough to make the wicking if put in place very tight to be choked down further, slowing down liquid flow to where the wick couldn't keep up with the heat generation and was becoming dry. If you add that into a situation where there is a hot spot, you are going to have some rough vaping time. Note also, this is all speculation without seeing how the coil is firing myself.
Any rebuildable atomizer, excluding builds that use Nickel Ni200 or Titanium T1 wire, before wicking the coil, pulse fire the coil, use a pair of tweezers or needle nose pliers to squeeze, pulse heat again, squeeze, rinse and repeat until the coil fires evenly. This pulsing and squeezing the coil technique allows the coil to anneal into proper position gently as well as allows the formation of the needed oxidation layer to form and insulate the wire from the rest of itself. This will allow the true resistance of the coil to be read, though note gradually over time resistance of a coil will increase, but not such a drastic change you will notice. I've had Kanthal coils increase by about 0.03ohms over a six month service and use period, just the physics of the metal crystalizing internally due to contant heating and cooling.
May be TMI for you, but if you are just getting into rebuildables, knowing something about everything going on with a coil helps in troubleshooting problems. Note the caution above about Ni200 and Ti1 wire, never dry fire these wires, Ni200 is soft, very soft with a very low melting point so you could melt your coil and collapse it during dry firing, also out gas Nickel into your vape. Titanium when dry fired creates an oxidation layer of Titanium-Dioxide which is not healthy for you. Also both wires should be only used in Temperature Control mode, Stainless 316L, NiChrome, and Kanthal should only be pulse fired when not wicked during initial build or when dry firing to clean the coils during a re-wicking.
