Voltage Drop Test Video for SLR Coils

[SteveW]

Anyone know of any video of testing with a meter for voltage drop on sub 1ohm coils? I am in a discussion at the moment with someone who claims their testing reveals that those using slr coils will never be running power greater than 12 watts due to voltage drop under load (with a 3.7v battery). I have seen a few videos that display small voltage drop when the meters are set to max load and the atty is only run for a second or two. I was under the impression that higher wattages are routinely achieved by those using slr setups. Is the voltage drop really that significant after a short period of time? I am a little out of my depth on this and he seems to know his stuff (electrically speaking anyway) but intuitively, something seems off about his claims. Hope this makes sense to someone .

 

[pdib]

Hey, SteveW, Jasl90 posted this link in another thread. It includes some "math" on the effect of SLR coils (and goes on to say that an older/used-ish battery is the biggest issue). Good luck. Voltage Drop - Not Where You Think | atmizoo vaping modware

 

[SteveW]

Hey, SteveW, Jasl90 posted this link in another thread. It includes some "math" on the effect of SLR coils (and goes on to say that an older/used-ish battery is the biggest issue). Good luck. Voltage Drop - Not Where You Think | atmizoo vaping modware

Thanks mate. and really, that seems to confirm what the guy is saying as I read it. These paragraphs particularly interesting:

One obvious property of this simple circuit is that the lower the atomizer resistor, the higher the current. However, there’s a catch: Higher current translates into a higher voltage drop and higher losses on the in-series resistance that represents the mod. For example, if a mod with an ideal 4V battery has a 0.1 Ω resistance and the atomizer resistance is 1.9 Ω, then the voltage drop will be 0.2 V and 3.8 V will be applied on the atomizer resistance. When using a 0.9 Ω atomizer resistance, the voltage drop will be 0.4 V and 3.6 V will reach the atomizer.

In terms of power, in the first case 0.4 W will be losses and 7.6 W useful power ( 5% lost ), while in the second case 1.6 W will be losses and 14.4 W useful power ( 10% lost ).

So I guess the question is, are the claims of vaping at 16w or 18w or even 20w incorrect with mechanical mods? Seems to be people apply Ohm's Law without accounting for voltage under load.

 

[pdib]

They are certainly incorrect, the question is how much? Also, however, the wattage we report is a means of communication between vapers, not an Olympics doping scandal. None of us can report accurate Wattage, because wattage is a scale of energy PRODUCED, and we aren't actually measuring our atties temperatures and adding in the amount of energy converted to vapor in volume. We are comparing our experiences using one particular formula. We punch in the numbers we know, we get communicable and comparable data, and we all know what we mean when we say what we say.

IMHO

 

[SteveW]

Thanks Pdib, well put. Still really interested in some video of real world testing on SLRs. I saw one video on the Gus which I posted in the thread. The spring was replaced with a Caravela brass post and the voltage under load increased by 0.7v to 3.71v with a 1 ohm coil attached (in a DID with a brass post). Under these conditions applying Ohm's Law would be valid in my opinion and the calculated wattage under load comes out a 13.8. The objection raised when I put this up was that the multimeter was set to capture peak voltage and that the test only lasted a very short time. As it was a freshly charged battery the comment was also made that the voltage seen would quickly drop (matter of seconds) to what would really work out to be power of around 12watts. If someone has a multimeter or knows of a vid somewhere I would really like to see a test like this sustained for a short time to see if voltage does plunge as claimed.

 

[gdeal]

They are certainly incorrect, the question is how much? Also, however, the wattage we report is a means of communication between vapers, not an Olympics doping scandal. None of us can report accurate Wattage, because wattage is a scale of energy PRODUCED, and we aren't actually measuring our atties temperatures and adding in the amount of energy converted to vapor in volume. We are comparing our experiences using one particular formula. We punch in the numbers we know, we get communicable and comparable data, and we all know what we mean when we say what we say.

IMHO

pdib, we can measure wattage, but we cant in real time measure wire temp. I think the formula stands, but the factors you mentioned affect wire temp and that is why even with a the same setup specs (ohms, wire size, voltage, wick material, etc...) you can only get close to replicating a vape, not duplicating it. That said, I do understand what you said above.

Thanks Pdib, well put. Still really interested in some video of real world testing on SLRs. I saw one video on the Gus which I posted in the thread. The spring was replaced with a Caravela brass post and the voltage under load increased by 0.7v to 3.71v with a 1 ohm coil attached (in a DID with a brass post). Under these conditions applying Ohm's Law would be valid in my opinion and the calculated wattage under load comes out a 13.8. The objection raised when I put this up was that the multimeter was set to capture peak voltage and that the test only lasted a very short time. As it was a freshly charged battery the comment was also made that the voltage seen would quickly drop (matter of seconds) to what would really work out to be power of around 12watts. If someone has a multimeter or knows of a vid somewhere I would really like to see a test like this sustained for a short time to see if voltage does plunge as claimed.

SteveW, I have tested sustained pulses under load. Under load the voltage drop does not go off a cliff during the pulse. It incrementally fades as the battery drains. Dont have a video and this is just observational, based upon a couple readings. I am not sure what the rate of fade is if you compared a fully charged battery to a somewhat depleted one. I am assume that it would follow the manufacturer rating curve at the lower voltage levels as well. But this would be a good find, if some know of one.

I have a current set up that is a .8 ohm 28g coil. Underload the battery at full charge is about ~3.8v. So the power is ~18watts at peak voltage. The battery quickly settles down to ~3.5v (~15 watts) and then has a slower fade in voltage drop.

I also have a set up that is .8 ohm but is a .8mm ribbon coil. It has the same length of wire, but surface area of the ribbon wire is 50% greater. This wire runs noticeably cooler (not overall wattage but in the quality feature of the vapor) than the 28g round wire and is due to great heat transfer factors. Hope that makes sense.

 

[SteveW]

SteveW, I have tested sustained pulses under load. Under load the voltage drop does not go off a cliff during the pulse. It incrementally fades as the battery drains. Dont have a video and this is just observational, based upon a couple readings. I am not sure what the rate of fade is if you compared a fully charged battery to a somewhat depleted one. I am assume that it would follow the manufacturer rating curve at the lower voltage levels as well. But this would be a good find, if some know of one.

I have a current set up that is a .8 ohm 28g coil. Underload the battery at full charge is about ~3.8v. So the power is ~18watts at peak voltage. The battery quickly settles down to ~3.5v (~15 watts) and then has a slower fade in voltage drop.

I also have a set up that is .8 ohm but is a .8mm ribbon coil. It has the same length of wire, but surface area of the ribbon wire is 50% greater. This wire runs noticeably cooler (not overall wattage but in the quality feature of the vapor) than the 28g round wire and is due to great heat transfer factors. Hope that makes sense.

Great stuff Gdeal, thanks for that. I have a multimeter coming and will run some testing of my own. I will also try some different mods to see how much they vary in voltage drop and try and capture what happens with a sustained pulse. Is peak or average voltage a fairer indication of what is happening under load? Do the meters allow you to capture average voltage over a period of time, say a 5 or 10 second pulse?

 

[gdeal]

Great stuff Gdeal, thanks for that. I have a multimeter coming and will run some testing of my own. I will also try some different mods to see how much they vary in voltage drop and try and capture what happens with a sustained pulse. Is peak or average voltage a fairer indication of what is happening under load? Do the meters allow you to capture average voltage over a period of time, say a 5 or 10 second pulse?

The meter I have only does "real" time. So basically, I'm watching the voltage readings during the sustained pulse based upon what ever the sample time frame is. The readings change fairly rapidly, under a second I believe, but they only jump around at .01 level. I am sure there are ones that record, but that goes beyond my tool box interests and probably bigger $$$.

 

[SteveW]

The meter I have only does "real" time. So basically, I'm watching the voltage readings during the sustained pulse based upon what ever the sample time frame is. The readings change fairly rapidly, under a second I believe, but they only jump around at .01 level. I am sure there are ones that record, but that goes beyond my tool box interests and probably bigger $$$.

That sounds like a very fair representation to me. Should be good enough for anyone to make a judgement about what is happening.

 

[jasl90]

The meter I have only does "real" time. So basically, I'm watching the voltage readings during the sustained pulse based upon what ever the sample time frame is. The readings change fairly rapidly, under a second I believe, but they only jump around at .01 level. I am sure there are ones that record, but that goes beyond my tool box interests and probably bigger $$$.

I will NOT use this as excuse to buy a Fluke 289... Repeating in my head over and over... Not checking prices on eBay and Amazon...

 

[USinchains]

I do 3 second pulses, with about 5 second rests. Voltage can drift down about 5 hundredths on my DMM, I use the average. Sometimes it doesn't drift down at all, like with a fully charged AW IMR 1600mah 18650, it actually climbs a few hundredths and sits there, even with a 5 second pulse. My coils are typically 1-1.3ohm 28-30g kanthal, batteries are high drain IMR 18650 and 350.

 

[gdeal]

I will NOT use this as excuse to buy a Fluke 289... Repeating in my head over and over... Not checking prices on eBay and Amazon...

LOL...Of course I checked. Lets see...Fluke 289 with accessories or bid on that Caravela #200...Do I want to test or do I want to vape and wonder about voltage drop?

 

[SteveW]

I just bought one of those Vischy VC99 meters. Hope it is good enough. Saw the vibe about the Fluke but $35 is the most I wanted to spend on a meter. Hopefully it is good enough to do some meaningful tests.

 

[jasl90]

LOL...Of course I checked. Lets see...Fluke 289 with accessories or bid on that Caravela #200...Do I want to test or do I want to vape and wonder about voltage drop?

Lol... I see we share the dilemma... Just bring myself blow that kind of money on a PV... I have to keep telling myself its just a battery holder.

Considering the topic... It would be interesting to see what the real resistance is on the top end mechanicals. Same for internal resistances of the batteries we use.

 

[SteveW]

Lol... I see we share the dilemma... Just bring myself blow that kind of money on a PV... I have to keep telling myself its just a battery holder.

Considering the topic... It would be interesting to see what the real resistance is on the top end mechanicals. Same for internal resistances of the batteries we use.

I have a brass Chi on the way which I want to test. I saw Todd's review where he did a voltage under load test on one with a tankometer and an atty with a 1ohm resistance and the drop he showed was 0.2v on a fully charged battery. Again, it was one of those split second tests that did not really show what I wanted to see over a meaningful period of time.

 

[pdib]

Oh, s--t, Jasl, didn't you put that cc away? Put it down, man! Walk away. Walk away.

 

[jasl90]

It's away and in another room.