RBA Coil Resistance changing

[Ambassador]

Hi Everyone

I am quite new to using the VV / VW and Genesis set up. I have been using my E-Vic with a Cobra rba for nearly a month now, and am still using my first coil.

When i made the coil i managed to just about get rid of the top hot spot and the resistance was noted as 1.7 Ohm. {I used 400 mesh for the wick which i thoroughly oxidised before and after wrapping with a blow torch, and used 4 wraps of Kanthal A1 32ga for the coil}.

The vapour production was ok, less than i expected but hey i was new to it so i just carried on vaping with it. After about 2 weeks the resistance changed to 1.8 Ohm, then a week later the vapour reduced so i stared fiddling with the coils and the resistance dropped to 1 ohm, then from this point it would change between 1 to 1.7 then 1.8 Ohm. Now it has gone up to 2.2 Ohm! Also the top hot spot is back and i cannot get rid of it. I am guessing this means the coil is about to die??? Or bunged up? I vape 80PG / 20VG.

I am going to make a new wick and coil today, using the drill bit method and would like to know your thoughts on how to maximise vapour production using 80 / 20 with a single coil set up, and any clues to why the resistance changes. Also one last question, most people seem to get a resistance of around 1.2 Ohm with the 4 wraps so maybe i screwed it up from day 1??

Cheers for any help

Phil

 

[ebhomepc]

Resistance changing seems to be a short that's usually the problem.

Sent from my Nexus 4 using Tapatalk 2

 

[Ambassador]

Hi ebhomepc

So i have made a new wick and coil, tried the drill bit method with tooth pick got 1.2 Ohm then could not get wick down the coils so made the coil the normal way wrapping around wick and its 1.5 Ohm...just jumped to 1.6 Ohm - No hot spots

Not sure if this is normal to get 1.6 Ohm with 4 wraps ???

Cheers

Phil

 

[Alexvac]

It's normal for the resistance to go up slightly as the coil gets more use, but that huge drop was likely due to a short somewhere on the coil. Either way getting a month on the same coil isn't bad at all.

 

[Ambassador]

Thanks for the info Alexvac, good to hear a month is a good run :O)

 

[Hello World]

Not sure if this is normal to get 1.6 Ohm with 4 wraps ???

If 32 ga Kanthal, you're good.

 

[Ambassador]

Hi Hello World yeah its 32ga Kanthal

 

[Oktyabr]

A short is the most likely cause of such behavior. Specifically? I'd check to make sure the screws were *tight* first. Even a bit loose, especially on the knurled nuts you are supposed to tighten with your fingers, can do that. Tank end of the wick lightly contacting metal on the inside, either the bottom of the tank or the part that goes through the wick hole isn't as thoroughly carbonized as you thought it was. Heat makes metal expand too, which can change things.

Last but not least a severely gunked up coil will allow the electricity to find short cuts through that wet crust too... remember, electricity *always* takes the shortest path (the path of least resistance).

28 gauge kanthal in a 5/6 around 2" of 500 ss mesh rolled *solid*. About two weeks old. Built it at 1.1 and only drops to 1.0 if I'm chain vaping hard and it gets very hot.

 

[Oktyabr]

On my vamo I've seen resistance change because there was juice in the 510 well! I'm in the habit of *never* over tightening anything and apparently that film of juice is enough to make a cruddy contact between the positive pin and the atty. Picking up the Vamo, vaping it, setting it back down again, made the atty shift just a microscopic bit changing the connection and changing the resistance measurement as well

 

[Ambassador]

A short is the most likely cause of such behavior. Specifically? I'd check to make sure the screws were *tight* first. Even a bit loose, especially on the knurled nuts you are supposed to tighten with your fingers, can do that. Tank end of the wick lightly contacting metal on the inside, either the bottom of the tank or the part that goes through the wick hole isn't as thoroughly carbonized as you thought it was. Heat makes metal expand too, which can change things.

Last but not least a severely gunked up coil will allow the electricity to find short cuts through that wet crust too... remember, electricity *always* takes the shortest path (the path of least resistance).

28 gauge kanthal in a 5/6 around 2" of 500 ss mesh rolled *solid*. About two weeks old. Built it at 1.1 and only drops to 1.0 if I'm chain vaping hard and it gets very hot.

Hi Oktyabr

Thanks for the informative reply.

The screws are defiantly tight (not overly so), and my new coil has settled on 1.7 ohm with 4 wraps around 400 mesh. I am surprised that it is so high......i tried the drill bit method once and got 1.2 ohm but then the coil was too tight to insert the wick. I second attempt the coil was 1.5 Ohm, but again too tight so using the "normal method" it came to 1.6, now 1.7 ohm after some use.

Using my Cobra and the E-Vic there is no juice on the atty connector

Cheers

Phil

 

[l0stm4n]

have you checked the insulator on the tank?
i dont own a rba yet but, at least you can cover all your bases.

 

[Ambassador]

Hi IOstm4n

Yes i have checked the grounds, they are ok