Ohms too high on power mode

[kj]

Hi everyone, New to the DNA 200, having a problem running my crown tank with 0.5 ohms the TC settings all fail so I switched it to power mode but now my device keeps spitting out ohms too high. Little about my setup, running an efusion duo with dual 18650 LG HG2s. Would appreciate your advice. Thanks, Kj

[VapingBad]

It is probably because the 2 cell variants are limited to 6 V output, 0.5 ? should be OK up to about 65 W, but running in power mode the warm res will be a bit higher. You need a lower res coil really.

https://forum.evolvapor.com/topic/67167-topic/?do=findComment&comment=904626

[dwcraig1]

What is the material of the coil and how many watts are you applying. 

[kj]

Hi dwcraig There seems to be a huge debate on the material but to the best of my knowledge the crown coils use SS316 but here's where the debate lies as I've read on multiple forums they suspect it has Nickel legs. Usually Vape between 55-70, apparently the recommended wattage by uwell is 40-70w. Thanks in advance for the help.

[kj]

VapingBad said:

It is probably because the 2 cell variants are limited to 6 V output, 0.5 ? should be OK up to about 65 W, but running in power mode the warm res will be a bit higher. You need a lower res coil really.

https://forum.evolvapor.com/topic/67167-topic/?do=findComment&comment=904626

Hey mate, Didn't mean to ignore you just saw your reply. on the move at the moment, what you said went straight over my head, will sit down have a second read of the link you provided once I get back home and update you. But I don't think that's the case will provide you with my battery settings as soon as I'm back. Thank you

[VapingBad]

kj said:

Hey mate, Didn't mean to ignore you just saw your reply. on the move at the moment, what you said went straight over my head, will sit down have a second read of the link you provided once I get back home and update you. But I don't think that's the case will provide you with my battery settings as soon as I'm back. Thank you

No probs, but I think that is what you're problem is.   When the board was designed it was just for 3 cells and had a max output voltage of 9 V.  Then after requests on this forum Evolv modified the firmware to allow it to run from 2 cells up to 133 W and the max output voltage also reduced to 6 V.  So the max resistance you can run at a give wattage is also reduced. 

It is easy to see if you attach to device monitor and the voltage is at 6 V you are on that voltage limit and you need to have a lower resistance to get more power.

[kj]

VapingBad said:

No probs, but I think that is what you're problem is.   When the board was designed it was just for 3 cells and had a max output voltage of 9 V.  Then after requests on this forum Evolv modified the firmware to allow it to run from 2 cells up to 133 W and the max output voltage also reduced to 6 V.  So the max resistance you can run at a give wattage is also reduced. 

It is easy to see if you attach to device monitor and the voltage is at 6 V you are on that voltage limit and you need to have a lower resistance to get more power.

On a non related topic, could you kindly explain to me how the resistance locks in the DNA am I right to understand that it automatically locks unless there is a variance of 25% it then resets it to the new reading. reason I ask is notice the resistance in the charts it spike to 65 ohms and not sure if its normal.

I've attached the charts one @ 55w the other @70w. I see it hits the 5.95 limit however shouldn't my batteries be able to withstand the higher needs (2x LG HG2 3000mAh 20A 3.7v). would t be accurate to say as long as I use the 18650s I wont be able to vape with high wattage unless I attached a higher rated ohm coil? or can I tweak the battery settings safely to allow for the higher draw.

Another thing I don't get and id probably get shot for this comparison but how come my cuboid 200 allowed this but the DNA doesn't.

   

[BillW50]

kj said:

On a non related topic, could you kindly explain to me how the resistance locks in the DNA am I right to understand that it automatically locks unless there is a variance of 25% it then resets it to the new reading.

If you lock in your ohms, it assumes this is the resistance at 70°F. When you leave it unlocked, it tries to figure everything out by the room temperature, coil temperature, etc. At least that is the way it seems to work for me.

kj said:

reason I ask is notice the resistance in the charts it spike to 65 ohms and not sure if its normal.

65 ohms? 

[kj]

BillW50 said:

If you lock in your ohms, it assumes this is the resistance at 70°F. When you leave it unlocked, it tries to figure everything out by the room temperature, coil temperature, etc. At least that is the way it seems to work for me.



65 ohms? 

Hello Bill,

sorry meant .65 

so in other words don't ever lock it, dna capable of assessing the situation and adapting accordingly. keep in mind I'm talking about power mode and not tc mode.

[BillW50]

Hahaha... ok about 0.65 ohms. In power mode, I wouldn't worry about the resistance unless it is jumping around a lot.

[VapingBad]

Yep, 0.65 ohm is too high to get more than about 55 W from 2 batteries because of the 6 V max output voltage, you need to build below 0.27 to get full wattage range, but even 0.4 ohm should get you up to 90 W.  See the table in my thread I linked to.   It is not the batteries, the board only converts voltage downward and 6 V is the max for 2 cells regardless of how good your batteries are, it is not really an issue with 3 cells or rebuildable atties, but is just a bit restrictive for 2 cell versions using pre-made coils heads.

[black lace]

The op if he hasnt allready got one can refer to an ohm's law calculator and there are a few including the just named ( ohm's law calculator) can be downloaded as a mobile phone app. the 0:65ohm/55watt shows just a touch below 6v, good little tools for nothing... """";;ya dont get much fa nothing these days lad""::

[kj]

VapingBad said:

Yep, 0.65 ohm is too high to get more than about 55 W from 2 batteries because of the 6 V max output voltage, you need to build below 0.27 to get full wattage range, but even 0.4 ohm should get you up to 90 W.  See the table in my thread I linked to.   It is not the batteries, the board only converts voltage downward and 6 V is the max for 2 cells regardless of how good your batteries are, it is not really an issue with 3 cells or rebuildable atties, but is just a bit restrictive for 2 cell versions using pre-made coils heads.

hello everyone,

great participation, really appreciate all your help.

ok so question, why is it changing to .65 ohms when im vaping a 0.5ohm coil that initially reads 0.51 ohms cold. based on the ohms calculator it seems the limitation kicks in only due to this rise in ohm reading which based on my understanding that it should not change and be set on the device be it in power mode of TC mode.

i get what your saying now though. I just wish i hadnt just bought 2 sets of these 0.5 ohm coils. luckly ive got a pair of .25s that i can test out.

 

[kj]

black lace said:

The op if he hasnt allready got one can refer to an ohm's law calculator and there are a few including the just named ( ohm's law calculator) can be downloaded as a mobile phone app. the 0:65ohm/55watt shows just a touch below 6v, good little tools for nothing... """";;ya dont get much fa nothing these days lad""::

i did but thought i was reading it wrong like i said its a 0.5 coil reading at 0.51 cold the calculator indicates it can go up to 70w but heres where it all goes wrong the reading changes after a hit to 0.65 and that requires higher volts.

but thanks for the tip.

[dwcraig1]

The board is continually sampling the coil resistance whether it's in power mode or temperature mode. The type of wire that you are using increases resistance as it heats up.

[kj]

dwcraig1 said:

The board is continually sampling the coil resistance whether it's in power mode or temperature mode. The type of wire that you are using increases resistance as it heats up.

so the behavior is spot on, well there you go you learn something new every day. The way I understood it in the past is the reading changes but not to this extent. When changing it would be by about +or- 0.03 ohms.

also if i understand the device correctly, its set to test and lock in a reading and only adjust it if it exceeds 25% as per the settings set on escribe under the manufacturer tab. in my case if my math skills dont betrey me, its exceeding the 25% and therefore locks in the new reading.

[dwcraig1]

What you are describing (lock),that just pertains to cold ohms, all the TC wire are going to increase resistance according to their composition when heated.
An example of how lock could be used: You need to change the battery (reboot) and the atomizer is hot, here you need to retain the cold ohms setting.

[BillW50]

I don't think that is how it works, kj. The DNA200 Datasheet is a good read about the operation of the DNA200. And on page four, it describes the 25% change in resistance. And that only comes into play if you remove an atomizer and then attach another one. On page six, under Resistance Lock. It describes what happens when the resistance changes while using the same atomizer.

[kj]

dwcraig1 said:

What you are describing (lock),that just pertains to cold ohms, all the TC wire are going to increase resistance according to their composition when heated.
An example of how lock could be used: You need to change the battery (reboot) and the atomizer is hot, here you need to retain the cold ohms setting.

BillW50 said:

I don't think that is how it works, kj. The DNA200 Datasheet is a good read about the operation of the DNA200. And on page four, it describes the 25% change in resistance. And that only comes into play if you remove an atomizer and then attach another one. On page six, under Resistance Lock. It describes what happens when the resistance changes while using the same atomizer..

ok that clarifies when to use the lock funtion, cause with other devices they instruct you to alway lock when using TC mode, power mode doesnt show as much fluctuations but thats just cause they are not as accurate as the DNA200.

i read the datasheet before but ill admit i did read it fast, i will probably give it a second read. they way its written or i should say the way i understood it was the way i explained it whereby it locks in the resistance cold and then will always fire at that resistance even with the change of resistance when heat is applied. if however there is a 25% change in resistance it will consider it as a new coil and set the cold resistance to the new reading.

now what i gathered is this happens automatically, when applying the manual lock function as stated by dwcraig it just fires at the set resistance @ when you locked it.

[black lace]

Uwell crown tank and build deck, or replaceable screw in coils, not the best of attys for pressision measurement and reliability,,, stainless steel in that,, not a fan, not a fan, oh no,....cant put it any moor mildly, someone had to tell ya...

[dwcraig1]

It only locks in the cold resistance, as the coil heats and the resistance rises the board continuously calculates the voltage needed to maintain the set wattage providing set temp allows for it. It just locks the starting point.  

[kj]

black lace said:

Uwell crown tank and build deck, or replaceable screw in coils, not the best of attys for pressision measurement and reliability,,, stainless steel in that,, not a fan, not a fan, oh no,....cant put it any moor mildly, someone had to tell ya...

yes its what ive gathered from all the posts ive seen.  shame though the tank could be promising.

[kj]

dwcraig1 said:

It only locks in the cold resistance, as the coil heats and the resistance rises the board continuously calculates the voltage needed to maintain the set wattage providing set temp allows for it. It just locks the starting point.  

got it, that does make sense. i guess this threads sorted, thanks for the help and info, hope to return the favour one day.

[black lace]

There are a lot of very nice ones about but the base connections let them down, (build deck or screw in coils onto a very poor reaching center pin) unless you have a "mod" with a fixed or screw type center pin (so you can screw down onto and get some pressure) Ni200 is a lot moor forgiving than the stainless, and the pre built coils, the wire is to thin and there usualy so tightly wicked that the juice flow is poor, if you reduce the wicking cotton for better flow, the thin wire will intermitantly distort. I think they came out a bit late in the game, just about ok with ni200 28/29 guage on the build deck if you can maintain a connection, and also as a starter kit as a mod and atty at a bargain price...................... ... everything i say is my veiw only, i am not an advocate of evolv... if you wish to sue me....be warned .. your not big enough..

[BillW50]

I use Subtanks and Crown RBAs all of the time. But I generally build with nickel. I used to use SS, but I got an awful smell and taste from SS, so I quit using it.