"voltage drop" rant

[vapo jam]

apologies in advance, as the title says, this is a rant:

i'm sick of reading about how "my xxx mod has a 0.05v drop" with no additional information... i realize most people have a limited understanding of electronics (not meant as a knock on anyone), but

THIS DOESN'T MEAN ANYTHING!

doesn't this bother anyone else?

i can take a mod made entirely of steel (contacts and everything), throw a 100 ohm coil on it, put in an almost-dead battery, and get a voltage drop so low you wouldn't be able to read it.

i can also take the exact same mod except made entirely out of silver, put on a .01 mohm (that's .00001 ohm) coil and a fresh battery and get damn near a 4.2v drop across the mod.

does this mean a solid steel mod hits harder than a solid silver mod???

yes, my numbers are very exaggerated; nobody vapes with a 100 ohm coil or a .01 mohm coil (well, at least i hope nobody vapes with a .01 mohm coil). does it make any difference? well, when we're talking about fractions of a volt on anything between a .1 ohm quad coil on an rda and a 5 ohm carto, and anywhere between 4.2 and 3.3 volts on a battery, yeah, it makes a BIG difference.

if you make a claim about your mod's voltage drop, can you PLEASE note your atomizer resistance and your battery level as well? at least this way, those of us who understand electronics will be able to make something out of it.

better yet, forget the whole voltage drop thing and measure the DC RESISTANCE of the mod instead. yes, this takes a little more effort and a little better equipment, but i absolutely guarantee that a 1 mohm mod will ALWAYS hit harder than a 50 mohm mod, no matter what topper you use.

 

[Mr.Mann]

Have you seen what jkuro has done at the CV forum with regard to testing the mods' voltage drop? I am not well versed enough (at all really) to really explain, but I can send you a link if you like. It ain't a voltemeter test, that's for sure.

Hey, wait a minute, I see you're from LA -- you probably already are familiar with it.

 

[K_Tech]

doesn't this bother anyone else?

It bothers me, because as you said, the numbers are meaningless the way they're done 90% of the time. But then again, I've got a background in electronics and electricity.

 

[anumber1]

I agree with your point that most of the time voltage drop is given without enough background info.

I also agree that resistance is a more important measurement.

I also have an electrical background and find it pretty astounding that so many people have so little understanding of the relatively basic principals in effect when using a pv.

 

[vapo jam]

Have you seen what jkuro has done at the CV forum with regard to testing the mods' voltage drop? I am not well versed enough (at all really) to really explain, but I can send you a link if you like. It ain't a voltemeter test, that's for sure.

Hey, wait a minute, I see you're from LA -- you probably already are familiar with it.

actually, i'm famililar with his charts, but didn't know who made them, so thanks.

obviously, i'm not suggesting everyone go out and buy an expensive power supply and test as extensively as he did, it just irks me when someone claims their so-and-so mod has a so-and-so voltage drop without any additional information about the way they tested it, the state of their batts and atty, etc.

i'd still contend, though, that the dc resistance of a mod is much more useful information than any sort of voltage drop. all of the data on jkuro's chart (and much more) can be calculated very easily if the resistance is known (granted, his data can be used to reasonably accurately calculate the resistance).

 

[K_Tech]

i'd still contend, though, that the dc resistance of a mod is much more useful information than any sort of voltage drop.

I have access to a DLRO; I may have to see if I can set up some sort of test rig... hmmm...

 

[vapo jam]

I have access to a DLRO; I may have to see if I can set up some sort of test rig... hmmm...

well, if you can get some resistance numbers, i'd personally be very interested in seeing the results

i've been thinking about it, and it seems to me that the most difficult part of getting an accurate resistance measurement would be consistently and reliably connecting the positive and negative battery pins with a known resistance. after that, measuring the resistance between the 510 threading and the center pin would be (relatively) trivial.

 

[K_Tech]

well, if you can get some resistance numbers, i'd personally be very interested in seeing the results

i've been thinking about it, and it seems to me that the most difficult part of getting an accurate resistance measurement would be consistently and reliably connecting the positive and negative battery pins with a known resistance. after that, measuring the resistance between the 510 threading and the center pin would be (relatively) trivial.

One thing I can't figure out is how to get those measurements without modifying the mech; I was thinking of using an 18650-sized insert with connections at the positive and negative ends, and measuring resistance from point A to point B with the fire button depressed, but I don't know how to do it without drilling holes in the mech.

Back to the drawing board in my head...

 

[vapo jam]

One thing I can't figure out is how to get those measurements without modifying the mech; I was thinking of using an 18650-sized insert with connections at the positive and negative ends, and measuring resistance from point A to point B with the fire button depressed, but I don't know how to do it without drilling holes in the mech.

Back to the drawing board in my head...

i think that's similar to what i was thinking - if you could find a chunk of metal about the size and shape of an 18650 with a known resistance, you could wrap it with some kapton or teflon tape, throw it in the mod, depress the fire button, and measure the resistance using a wired 510 fixture.

 

[ukeman]

apologies in advance, as the title says, this is a rant:

i'm sick of reading about how "my xxx mod has a 0.05v drop" with no additional information... i realize most people have a limited understanding of electronics (not meant as a knock on anyone), but

THIS DOESN'T MEAN ANYTHING!

doesn't this bother anyone else?

Oh yeah, I hate that too...

This thread is leading towards technical stuff and that's great... for some but not me.

But I can add a couple .01's regarding the OP theme:
1. Voltage drop info (how hard it hits) is one of the most important factors in defining or assessing a mech mod
2. along with contact and switch design.
That's it.

Given a set coil resistance (and a bunch of other stuff probably) V-drop reflects on materials (metals) and how well all the parts work to deliver the least resistance.
That's all the technological understanding I have and it don't mean squat unless I can properly compare the results to other mech mods.

I used to meter stuff with a DMM or inline meter until I found jkuro's chart...
Depending on what batt/atomizer/coil resistance etc we may use we will get variable results on the same mod - but because he uses a standardized method across the board, and as more and more mods get added and tested we get a reliable comparison.

Awesome free service finding out about one of those two supremely important considerations in choosing a mech mod; performance.

 

[MrPlink]

Not an EE by FAR, but thanks to tube amplifiers I have a fundamental understanding of electronics.

With mechs I have always felt like, who cares? Just wind a lower impedance coil and be done with it.

 

[vapo jam]

This thread is leading towards technical stuff and that's great... for some but not me.

But I can add a couple .01's regarding the OP theme:
1. Voltage drop info (how hard it hits) is one of the most important factors in defining or assessing a mech mod
2. along with contact and switch design.
That's it.

actually, the concept is relatively simple. if the resistance of your mod is the same as the resistance of your coil (let's say both are 0.2 ohms), then equal voltage will be applied to both; ie, a battery with a 4v charge would apply 2v to your coil and 2v to your mod, meaning your "voltage drop" is 2v.

if you take the same setup and add in a freshly charged battery (4.2v), then again, the mod and the coil would each see half the voltage (2.1v) since their resistances are equal.

let's change the scenario a bit and say the resistance of your mod is half the resistance of your coil (coil=0.2 ohms, mod=0.1 ohms). now, since the resistance of the coil is twice the resistance of the mod, it will see twice the voltage as well; just to make the numbers easy, a battery at 3v would apply 2v to the coil and 1v to the mod.

does this make sense? i completely agree that how hard a mod hits is an important metric, i just contest that the current definition (voltage drop) is unnecessarily confusing and usually meaningless.

 

[Izan]

Sorry... This all just seems like...like...

Cheney waving....


Cheers
I

 

[vapo jam]

I used to meter stuff with a DMM or inline meter until I found jkuro's chart...
Depending on what batt/atomizer/coil resistance etc we may use we will get variable results on the same mod - but because he uses a standardized method across the board, and as more and more mods get added and tested we get a reliable comparison.

sorry, just re-read your post and noticed the above passage. i agree that jkuro's tests are good and very likely reliable enough to make good comparisons, but as i said previously, the metric is unnecessarily complex. if the resistance of the mod is known, no other information is needed. it's just like the resistance of the topper; a .01 ohm mod will hit harder than a .04 ohm mod the same way a 1 ohm coil will hit harder than a 4 ohm coil. doesn't matter what the battery level is, what the topper is, etc, how hard the mod hits is fully defined by this one number.

 

[beckdg]

thanks for bringing this up. this has bothered me for some time. i tend to glaze over quickly during most conversations concerning voltage drop. what really gets me is when someone compares the voltage drop of 2 setups (even if it's the same setup with different builds and different batteries or the same battery at differing charge states) as if they're contrasting statistics that are comparable. (as if the data was relevant with more than one variable)

i'm not an EE, but i understand the basics. problem for me is i don't have access to the equipment to perform reliable tests.

 

[vapo jam]

thanks for bringing this up. this has bothered me for some time. i tend to glaze over quickly during most conversations concerning voltage drop. what really gets me is when someone compares the voltage drop of 2 setups (even if it's the same setup with different builds and different batteries or the same battery at differing charge states) as if they're contrasting statistics that are comparable. (as if the data was relevant with more than one variable)

i'm not an EE, but i understand the basics. problem for me is i don't have access to the equipment to perform reliable tests.

very well said. in the end, the thing we all want is a metric that we can use to compare the performance of different mech mods. regulated mods are easy, since we can look at the specs, the design, and the quality, and make a reasonably well-informed decision.

with mech mods, we can still look at the design and quality, but it seems for the most part we have to make assumptions on the electrical performance (this one is made of aluminum and that one is copper; this one has silver plated contacts and that one brass). wouldn't it be wonderful if we could just add all of that up into one metric and use it as a valid comparison against other mods, especially with the number of new mech mods hitting the market nowadays...

 

[ukeman]

sorry, just re-read your post and noticed the above passage. i agree that jkuro's tests are good and very likely reliable enough to make good comparisons, but as i said previously, the metric is unnecessarily complex. if the resistance of the mod is known, no other information is needed. it's just like the resistance of the topper; a .01 ohm mod will hit harder than a .04 ohm mod the same way a 1 ohm coil will hit harder than a 4 ohm coil. doesn't matter what the battery level is, what the topper is, etc, how hard the mod hits is fully defined by this one number.

So how do you go about finding the DC resistance of the mod?
And is jkuro (and by a different route - us taking an atomizer and inline meter ie on a mod to measure the diff under load) a round about way of measuring the resistance of the mod?

 

[WattWick]

I thought all measurements was done on a scale from "beast clouds" to "sick as ....".

Edit: Censoring got me... sick as babyfeeding appendages.

 

[K_Tech]

So how do you go about finding the DC resistance of the mod?
And is jkuro (and by a different route - us taking an atomizer and inline meter ie on a mod to measure the diff under load) a round about way of measuring the resistance of the mod?

It's roundabout, and can be a good benchmark, but the problem with batteries and buttons is that no two batteries and no two button presses are 100% identical, and even the same battery can behave differently from one vape to the next.

They're close enough that you're not going to get an extremely noticeable difference from one vape to the next, but for precise measurements, it's like using a tape measure when you need a micrometer.

The resistance of the mod itself is pretty much a fixed quantity - if it reads .0225 ohms from the bottom contact to the top cap, it's always going to read that unless the threads are dirty or its molecular structure changes.

I thought all measurements was done on a scale from "beast clouds" to "sick as ....".

Edit: Censoring got me... sick as babyfeeding appendages.

Lol. As much as I enjoy an enthusiastic reviewer, there's a point where I like having more objective and less subjective. Impressions and feelings are great, but multimeters and oscilloscopes need love too!

 

[vapo jam]

So how do you go about finding the DC resistance of the mod?
And is jkuro (and by a different route - us taking an atomizer and inline meter ie on a mod to measure the diff under load) a round about way of measuring the resistance of the mod?

the first question is a little more difficult; K Tech and i were bouncing around some ideas above, but the fact remains that it's not easy to accurately measure the resistance of a mod without some pretty good equipment. the device he has access to can measure in the range of micro-ohms (that's one millionth of an ohm), which is definitely good enough, but then the problem becomes hooking it up correctly to take an accurate measurement.

the answer to your second question is yes. the voltage drop across everything (mod and atty) will always be the same as the voltage of your battery, meaning if your battery is at 4v, the voltage drop across the mod plus the voltage drop across the atty will add up to 4v. obviously, if more voltage goes to your mod, less goes to your atty, which is why mods with a low voltage drop are seen as better.

the way these drops are related is by the resistance. for the sake of simplicity, let's say the mod's resistance is 1 ohm and the atty's is 2 ohms. in this case, the atty will have twice the voltage drop of the mod. since we know that the battery is at 4v (and therefore the total voltage drop must add up to 4), we can calculate that 1.33v will go to the mod, and 2.67v to the atty.

if we keep the same mod and replace the 2 ohm atty with a 3 ohm atty, we now know that the atty will have 3x the voltage drop of the mod. in this case, 3v will go to the atty, and only 1v will go to the mod.

does this make sense? i try not to get too technical, but i work with electricity every day, so my perception of what's "too technical" may be a bit skewed...

also, your second question is brilliant. we don't have to directly measure the resistance of the mod if we can (VERY) accurately measure the difference between the total voltage drop vs the drop over the atty... jkuro's tests are good, but not quite accurate enough if he's getting 0.00v drops in some cases.

hmm, this gives me an idea, now if only i had some (very expensive) voltmeters...