advanced batt question

[gankoji]

To get a good idea of what the total circuit resistance is, you can always measure the voltage across the posts of your atty. You will have to do a bit of circuit analysis to find internal resistance and power loss through the mod/atty and such, but using a high quality DMM (with internal resistance generally greater than 1Mohm) is a much more accurate method than the inline meters available today.

As long as you're using a battery rated for greater than 10.5 amps (plus a margin), there really should be no issue vaping at .4. Just be cautious, because loose connections and other nuances can fool you into thinking a .2 coil is actually .4 .

 

[scabbytattoo]

ya no worries on the safety I know where my limit is and i'm very far from it. thanks for all the input guys, and to the people how say .4 vs .6 or just do a higher ohm...........If you don't have any input in this thread then why post at all other then to make yourself look like an .... this wasn't a question on what is safe or what YOU like to vape at, it was a question on getting the most accurate reading from an unregulated mod. Again thank for all the numbers and input it's nice to see some people are still holding ECF down like in the old days (eg: being helpful instead of trolling on subject you know nothing of).

 

[scabbytattoo]

Just build the ohms higher....again do you have to vape at .4? Just to do it...

you didnt read any of this thread. dont make it a common thing or no one will ever take what you post seriously.

 

[xpen]

Just keep in mind that resistance varies with the coil temperature, and with time (use)... While coil R normally increases a bit with time, it does decrease with temperature.

By the way: sub-ohm resistance measurement is a leap of faith in your multimeter... most of the models on the mass market aren't very accurate.

This is to say that you may start vaping (apparently) safe and still end up kaboom

 

[Rader2146]

To get a good idea of what the total circuit resistance is, you can always measure the voltage across the posts of your atty. You will have to do a bit of circuit analysis to find internal resistance and power loss through the mod/atty and such, but using a high quality DMM (with internal resistance generally greater than 1Mohm) is a much more accurate method than the inline meters available today.

As long as you're using a battery rated for greater than 10.5 amps (plus a margin), there really should be no issue vaping at .4. Just be cautious, because loose connections and other nuances can fool you into thinking a .2 coil is actually .4 .

The spreadsheet that I liked in post #13 does a lot of the circuit analysis for you, but it's only as good as the inputs. The resistance values can make a HUGE swing being that we are dealing with milliohms and only specialized meters are accurate at that resolution.

Just keep in mind that resistance varies with the coil temperature, and with time (use)... While coil R normally increases a bit with time, it does decrease with temperature.

By the way: sub-ohm resistance measurement is a leap of faith in your multimeter... most of the models on the mass market aren't very accurate.

This is to say that you may start vaping (apparently) safe and still end up kaboom

Resistance actually increases with temperature, but only slightly. 3% at most for Kanthal grades and the temp that we experience.

 

[xpen]

(...) Resistance actually increases with temperature, but only slightly. 3% at most for Kanthal grades and the temp that we experience.

Then considering the range of temperatures we use for vaping, we should see no difference whatsoever in resistance for Kanthal wire.. For instance (pure, 100%) VG boils at 290C, so that puts a cap to the temperature an atomizer can reach.

Anyway, based on my own practical experience with microcoils, sustained heating periods make resistance decrease slightly... slightly, but enough to be measured by the DNA20 - so in the 0.1 ohm range.

That's possibly because two wraps get in touch when heated, who knows, but nevertheless if you're starting from 0.4 ohm there isn't a lot of margin for error...

 

[gankoji]

Just keep in mind that resistance varies with the coil temperature, and with time (use)... While coil R normally increases a bit with time, it does decrease with temperature.

By the way: sub-ohm resistance measurement is a leap of faith in your multimeter... most of the models on the mass market aren't very accurate.

This is to say that you may start vaping (apparently) safe and still end up kaboom

This is an excellent point about standard 'hobby' DMMs. When in the meat of the sub-ohm range, I prefer my LCR meter over any DMM. YMMV .

 

[pdib]

Then considering the range of temperatures we use for vaping, we should see no difference whatsoever in resistance for Kanthal wire.. For instance (pure, 100%) VG boils at 290C, so that puts a cap to the temperature an atomizer can reach.

Anyway, based on my own practical experience with microcoils, sustained heating periods make resistance decrease slightly... slightly, but enough to be measured by the DNA20 - so in the 0.1 ohm range.

That's possibly because two wraps get in touch when heated, who knows, but nevertheless if you're starting from 0.4 ohm there isn't a lot of margin for error...

it has also been my experience that immediately after glowing and scrunching a micro coil I'll get a resistance reading that's lower by .1Ω (maybe more but never more than .2Ω). Once the coil has cooled off, the res. is as expected. Obviously, when vaping, the coil doesn't get anywhere near that hot.