Resistance reading too high on TC profiles

[Wolfgar]

Hello, I need a bit of a help with my DNA 250 device (think vape finder 250). Sadly TC had been useless on it for a while as it reads resistance always 0.01-0.03 Ohm too high but only when in TC profile. When I switch to power profile it shows precise resistance perfectly. I used my koopor to test it as that one allows you to set the resistance (I wish DNA would let me fine tune the resistance) and using the resistance DNA reads in power mode TC on koopor works perfectly. But when I switch my DNA to any of the TC profiles the resistance suddenly jumps up for no reason (cold atomizer of course). When the profile loads it actually shows correct resistance for split second and then goes up but it's way too quick to lock before it changes.

It does this on all my SS builds with every atomizer I use and at any resistance from down to 0.08 to 0.4Ohm. I use multiple TC SS profiles -  original that had been pre-installed, TCR and few I downloaded and they all read same wrong resistance.

[Wayneo]

Welcome. IMHO you're way overthinking things, and TC is actually quite simple to set up and get good results.

29 minutes ago, Wolfgar said:

I use multiple TC SS profiles -  original that had been pre-installed, TCR and few I downloaded and they all read same wrong resistance.

Material TCR is wire specific and will not change due to ANY coil parameters. The resistance of the coil is ONLY read when you press the fire button. It is a 'live' read while in Power mode. It is a 'refined' (70°F) value while in TC mode when unlocked and does not change on the display while firing. DNA mods only require locking under special conditions.

40 minutes ago, Wolfgar said:

Sadly TC had been useless on it

What do you mean?

[Wolfgar]

23 hours ago, Wayneo said:

Welcome. IMHO you're way overthinking things, and TC is actually quite simple to set up and get good results.

Material TCR is wire specific and will not change due to ANY coil parameters. The resistance of the coil is ONLY read when you press the fire button. It is a 'live' read while in Power mode. It is a 'refined' (70°F) value while in TC mode when unlocked and does not change on the display while firing. DNA mods only require locking under special conditions.

What do you mean?

Not as much overthinking as troubleshooting really, when it used to read resistance properly I had been using just one profile happily but when the trouble began I tested multiple profiles.
Same with different coils as yes it's wire specific but multiple coil build that heats up unevenly, has hotspots or some conductivity issues in the build deck itself will of course affect resistance and hence the performance of the TC. I agree that getting TC working correctly on single coil is easy but on triple/quad RBA's I use it requires bit more fine tuning. But I'm used to that and I tested all of the builds that read incorrectly on my DNA on my other TC devices where they do work fine.

And yes, TC is useless on my DNA now since as I said, I have for example 0.12Ohm build, I put it cold on DNA in watt mode and the live resistance read is indeed 0.12Ohm. I take it off, switch to TC mode I put it still cold on and it shows correct 0.12Ohm for a split second and then inexplicably jumps up to 0.14Ohm and saves that as cold temperature. Now of course the TC doesn't work because I tries to work of way too high resistsance. Which means in most cases it'll just show something like few thousand degrees and then turns off or if I'm lucky and it reads only 0.01Ohm off I might be able to get it working somehow but setting ridiculously low temperature so I let mod regulate to 100C while realistically I'm vaping around 200.

[Wayneo]

Thanks for that level of detail. It could be a few things then, but all leaning towards a poor connection .... somewhere. I would check in this order, seeing as you said ALL atty's.

Check your ground connection inside the mod.

Clean your 510 connector and threading with a Q-Tip. I use IPA or windex.

35 minutes ago, Wolfgar said:

... getting TC working correctly on single coil is easy but on triple/quad RBA's I use it requires bit more fine tuning

Wouldn't that lead you to believe it's a build issue? I've never built a quad, but all your coils need to be as close to identical as possible.

Using Atomizer Analyzer, you can see if your build is stable (it will jump a few thousandth's at a consistent interval as AA applies 1watt). You can also 'set' you resistance there. You might also want to lock your resistance which negates refinement.

BTW, have you actually set your Mod resistance? 

[Wolfgar]

That's what I had been worried about, it'd explain why before it used fine as liquid could get inside the mod of course but so far I assumed that if that had been the cause I'd see bad reading on live reading in watt profile as well, I only get bad reading on cold coil reading of TC profiles but I guess taking it apart is inevitable then, i avoided it mostly since it uses some tiny star shaped screws I don't have screwdriver for so I'll have to buy it.

And if it'd be build issue It wouldn't work on other mods fine. I second test everything on my koopor and I took lot of care fine tuning my builds.

I chcecked it and it had been preset by manufacturer, I guess I could try reset it and fiddle a little. But again I concluded if that was issue both cold resistance and live resistance would be off, not just the later. Also I tried escribe monitoring and what caught my attention is that when I try to monitor both set cold resistance and live resistance they both move up copying each other curve. I think when I used monitoring before cold resistance remained straight line and only live resistance moved up as it is logical really. Could it be relevant?

[Wayneo]

Could be a combination of many things, but for the resistance to rise, it could be say a hotspot on a coil, or even a coil leg is slightly loose and when the wire it expands slightly, tightening the connection. The other stuff I mentioned was just getting you to a known stable base.

41 minutes ago, Wolfgar said:

And if it'd be build issue It wouldn't work on other mods fine. I second test everything on my koopor and I took lot of care fine tuning my builds

I can't agree with this, and realize every manufacturer uses different algorithims to do their TC (how often they read the change in resistance, when/how they calculate if a material is TC capable, etc.). I don't believe any other mfgr does 'refinement'.

I wouldn't fiddle with your mod resistance, unless you know how to set it accurately (5 minute job), we're talking down at the thousandth's value.

I'm surprised your Koopor reads the same value when both are in straight power mode.

Have you have proven a single coil in TC works (the chip itself)?

Did you look at Atomizer Analyzer? You might want to lock your resistance 

Yes, the cold ohm value should be a steady line, and if yours moves that explains why it's no bueno for TC

Edited November 5, 2017 by Wayneo

[Wayneo]

Not directly related to your issue, but here's a proven method to test/set your internal mod resistance. Remember to set it to zero, and upload to your device beforehand.

** giz_60 alternative mod resistance calculation **
Read this 1 comment by giz https://goo.gl/m8zrFH
Then
Wire picture (March 10 post) https://goo.gl/3BSsMV
Takes a few minutes, and it will be correct for YOUR mod.
IMHO, acceptable values would be in the .002-.009 range. Note the double zeroes.

Set to new value, upload settings to device.