Difference in OHM reading between reader and MOD

[Naheed]

Hi all,

Whenever I build a coil and check it on the reader it always defers from the the mod reading. For example, the coil I have reads .49 ohm on the reader and .42 ohm on the mod. Is this normal? I currently have a 5 wrap kanthal 24 2.5mm ID coil on serpent mini. I am using the Coil Master reader that came with the DIY kit.

Thanks.

 

[Cf11]

Hi all,

Whenever I build a coil and check it on the reader it always defers from the the mod reading. For example, the coil I have reads .49 ohm on the reader and .42 ohm on the mod. Is this normal? I currently have a 5 wrap kanthal 24 2.5mm ID coil on serpent mini. I am using the Coil Master reader that came with the DIY kit.

Thanks.

Don't worry about it. This difference is normal because of the chipsets in each device being different. Vape on.

 

[Carnage9270]

Chipsets, wire gauge, wire length, 510 material....on and on...

 

[Cf11]

Well if the same atty is being used on the other mod then the coils are gonna be the same along with the 510 on the atty.
The only things that can make a difference is the chipset and the 510 on the mod.
Oh well 0.07 is not too much of a difference on a regulated mod anyway, so it doesn't matter.

 

[sonicbomb]

Perfectly normal, move on,

 

[IDJoel]

No worries @Naheed,
There are a LOT of things that will affect the resistance in a circuit, and the circuit is NOT just the coil and atomizer. Every contact, solder connection, length and size of wire, and component composition, has the opportunity to influence resistance. Unless you are using bench testing caliber equipment AND measuring the coil directly (by which I mean from one end of the coil to the other); close is the best you can hope for.

After I read your initial post, just for giggles, I put the current RTA I was vaping, on 2 different mods, my atty tester, and a Fluke multi-meter. These were the results:
Mod #1 (ELeaf iStick TC100W):1.55 ohm resistance
Mod #2 (Joyetech Cuboid): 1.89 ohm resistance
Generic $10(US) atomizer tester

: 1.53 ohm resistance
Fluke 83V multi-meter (econo Fluke; don't be impressed): 1.52 ohm resistance

The results aren't particularly surprising. I expect the Fluke to be most accurate, and I new the Cuboid has poor readings due to the huge zinc heat-sink (which makes up part of its internal circuit to the atomizer, and zinc is a lousy electrical conductor compare to gold, silver, copper, tin and even brass), but I was a little surprised the econo tester was closer than the ELeaf, only because of the price point difference.

Bottom line: if you are under a tenth of an ohm (<0.10 ohm) difference, I wouldn't even think twice; a quarter ohm (>0.25 ohm) I would want to start digging deeper to find out why; and a half ohm (>0.50 ohm) I would be looking to see what needed to be cleaned, tightened, or retired/thrown out (if I am working in the margins of my batteries safety range... a half ohm can become significant). The Cuboid reading would give me concern; except I know what is causing the discrepancy.
I hope that gives you a little piece of mind.

 

[DaveP]

Dissimilar metals, accuracy of the chip algorithm, and contact characteristics all play into the readings you get from an ohm meter. As long as it's accurate to a tenth of an ohm I wouldn't worry.

When you screw on an atomizer the contact in the mod is spring loaded. Sometimes, you can screw and unscrew the atty and get readings all over the place depending on whether the contacts are touching squarely or at a slight angle or whether there's crud on the contacts.

1.52 is virtually the same reading as 1.55. The hundredths digit will be all over the place and may change slightly as you screw it on and off.

 

[Carnage9270]

Well if the same atty is being used on the other mod then the coils are gonna be the same along with the 510 on the atty.
The only things that can make a difference is the chipset and the 510 on the mod.
Oh well 0.07 is not too much of a difference on a regulated mod anyway, so it doesn't matter.

I think your misunderstanding what I meant by wire. Im talking about internally in the mod itself. I can have 2 of the same devices by the same manufacturer and get slightly different readings. If all these mods only went to one decimal place, most wouldn't even notice the difference.

 

[DaveP]

Naheed, I once tried the same atomizer on several mods and reported the different readings in a thread similar to this one. All were the same value on the tenth digit, but the hundredths digits were all over the place even after cleaning the contacts and the 510 male and female threads. If you try that you may find the same results.

In your post #8 I'd guess that there may be variations in the mod chip, wiring contacts, or the metal used on the 510 threads themselves. The threads vary in metal types between atomizers and mods. If it vapes, use it. Most all atomizers vary readings with the same atomizer.

There's always a possibility that the 510 pin in the atty isn't tight or it's tight, but not fully contacting the mod center pin. That's a direct path from the positive deck block to the mod center pin. If you had to back it out to make contact, then that could be part of your list of suspects.