What is the resolution of the resistance measurement?

[Bobby]

Couldn't find it in the spec's or on the forum but I'd like to know, just out of curiosity;
what is the resolution of the resistance measurement? 0,001 ohm or even smaller?

Off course the reason I couldn't find it might be that it is commercially confidential. In that case: I promise I won't tell anybody .

[JaySoCal]

In another thread about temp control John or Brandon said it is .000000 or .00000000 did a quick search but couldn't find it might of been before the Korean spam invasion.

[Bobby]

I did not yet get an answer to this question. Now I recently started to vape on Stainless Steel and see a vape that is a lot less smooth than Ti (see picture). I suspect that this is due to the fact that the ?R per degree is close to the measurement resolution.
Does anybody know what this is for the DNA200?

[Mad Scientist]

What is the cold resistance of your stainless coil? You could try wrapping your coils with increased cold resistance (within reason) to "leverage" the low TCR of stainless. The actual resolution and practical resolution are going to be different (likely very different). At a point, electrical noise in the environment will drown the measurement. Even measuring to "just" milliohms accurately is not a trivial task.

[Bobby]

Thanks for the reply. The 'jumpy' vape is not a problem since it stays within an acceptable margin but I am looking for a confirmation of my assumptions. I am aware that a higher 'cold' resistance will increase the accuracy.
The cold resistance of the SS304 dual coil is 0.47 Ohm. With a TCR of 0.00105, I will get a ?R per degree C of ~0.5 mOhm. If this is the measurement resolution (or lower than it), it would explain the 'jumpy' vape.

[VapingBad]

The top 2 are a 0.049 ohm dual twisted Ni200 build in an Aromamizer, if the TCR is 0.00641 then ?R per degree C is ~0.314 milliohm, preheat was 100 W. 
The 3rd is a 0.224 ohm 0.4 mm TiG1 dual build in an Aromamizer, if the TCR is 0.00366 then ?R per degree C is ~0.82 milliohm, preheat was 100 W.
The bottom one is a dual 0.5x0.1 ribbon Ni200 on stainless steal wicks in an Origenny V2, if the TCR is 0.00641 then ?R per degree C is ~0.3 milliohm, preheat was 80 W. 

All are smoother than the ss above, so I don't think resistance resolution is the reason as 2 of those plots have a much lower ?R per degree C.

 

timescale was 10 sec, but cropped to 6-7, but they are all the same scale.

[Bobby]

Very useful information. Thanks.
Now I know that the measurement resolution is not the cause (and is probably better than 1 mOhm), so I can look for improvement in another direction.