Firing mod at lower ohms than rated

[An0maly]

Hello,
I got a subox mini c, which is rated to fire down to 0.3 ohms. Today i bought the rta for the joytech ultimo and some clapton wire. After I installed my first coil i realizied that it was only 0.15 ohm, but I still tried to fire it and it worked. I also did the Ohms Law math and the ampere wasn't even close to 20. (around 10)
So is it safe to fire a 0.3 ohm rated mod at lower ohms?

 

[tj99959]

Resistance alone means nothing. What voltage or wattage were you using that coil at?
That .15 ohm coil @ 20a is only firing at 3v. So if you are only at 10a it would be trying to fire at 1.5v. I doubt that the mod can do that.

 

[An0maly]

Honestly I don't know anymore, but after that I have installed a 0.25 ohm notchcoil that came with the RTA. The V output at 27W is 2.59V at 35 Watts it goes up to 2.95V. I don't go any higher than that on this coil

 

[An0maly]

Update: I now have made a 0.15 flat clapton coil and it vapes great. At 30W it runs at 2.1V and has 14A output. At 40W (haven't tried vaping it at that wattage yet) it would be 2.45V and 16.33A.
So there's no reason to assume there's any danger, right?

 

[NOVA jon]

Why is it important for you to build that low to begin with?

 

[An0maly]

It isn't. It's just the ohm I ended up with the wire i bought. And I don't see a reason to buy a different wire, if it's safe to use it. Since everything worked perfectly so far I'm just gona stick with this build

 

[NU_FTW]

where are you getting your math??

 

[smacksy]

It isn't. It's just the ohm I ended up with the wire i bought. And I don't see a reason to buy a different wire, if it's safe to use it. Since everything worked perfectly so far I'm just gona stick with this build

Ohms are determined by how many wraps for your coil (resistance) with any wire....

Sent from my XT1585 using Tapatalk

 

[NOVA jon]

So why not just add a few more wraps and "be on the safe side" of things!!

 

[NU_FTW]

you are doing your math incorrectly to determine your amp draw. in a regulated mod you divide the Watts by sum of the batteries min voltage 3-3.1 per battery. Not by the volts your mod says it is firing coil at. So in a single battery config you divide 40 (watts) by 3 (min voltage of single cell). For total amp draw of 13.33. If it is dual 18650 you add the two min voltage together so 3 + 3 =6 divide 40 by 6 and you get a 6.66 amp draw

 

[David Wolf]

Hello,
I got a subox mini c, which is rated to fire down to 0.3 ohms. Today i bought the RTA for the joytech ultimo and some clapton wire. After I installed my first coil i realizied that it was only 0.15 ohm, but I still tried to fire it and it worked. I also did the Ohms Law math and the ampere wasn't even close to 20. (around 10)
So is it safe to fire a 0.3 ohm rated mod at lower ohms?

My recommendation is to never operate a mod outside of the manufacturers specifications, they're there for a reason. The specs have a margin of safety built in for the design and you're going beyond that.

 

[SteveS45]

Steam Engine is your friend here let me introduce you.................

Steam Engine main page

 

[Layzee Vaper]

you are doing your math incorrectly to determine your amp draw. in a regulated mod you divide the Watts by sum of the batteries min voltage 3-3.1 per battery. Not by the volts your mod says it is firing coil at. So in a single battery config you divide 40 (watts) by 3 (min voltage of single cell). For total amp draw of 13.33. If it is dual 18650 you add the two min voltage together so 3 + 3 =6 divide 40 by 6 and you get a 6.66 amp draw

Please be careful, using the above equation is incorrect. You have to account for the efficiency of the Mod.


You need to know:
The power output
The efficiency of the chipset. (usually between 80% and 95%)
The mods low battery cut off point (usually around 3 volts)
The CDR of the battery. ( I use mooches results rather than manufacturer spec as these are often inflated)

This information should be within the specifications or the instructions that came with the mod.

If you put the above information into the battery drain calculator on steam engine (Battery drain) It will tell you how much current is being drawn from the battery. Make sure that the maximum current draw is below the tested CDR of the battery.

My recommendation is to never operate a mod outside of the manufacturers specifications, they're there for a reason. The specs have a margin of safety built in for the design and you're going beyond that.

Yep, and there is simply no advantage to building very low resistance coils on a regulated mod. In fact a higher resistance coil with more wraps and more surface area makes much more sense.

 

[Bunnykiller]

Ohms are determined by how many wraps for your coil (resistance) with any wire....

Sent from my XT1585 using Tapatalk

what happens if the wire is straight???

 

[Eskie]

what happens if the wire is straight???

Then it's really challenging to wick.

 

[Bunnykiller]

guess I'll have to invent the " Tree Snake wick"

 

[KenD]

Ohms are determined by how many wraps for your coil (resistance) with any wire....

Sent from my XT1585 using Tapatalk

The length and gauge of the wire actually. A 10cm piece of 28ga ss316 wire will have the same resistance whether it's six wraps with a 4 mm id or 11 wraps with a 2 mm id.

Sent from my K6000 Pro using Tapatalk

 

[smacksy]

The length and gauge of the wire actually. A 10cm piece of 28ga ss316 wire will have the same resistance whether it's six wraps with a 4 mm id or 11 wraps with a 2 mm id.

Sent from my K6000 Pro using Tapatalk

You're right Ken, thx

Sent from my XT1585 using Tapatalk

 

[Sludge Van Diesel]

I'm having a similar dilemma although with shop bought attys.

I've got an e-pipe that has been discontinued & I'm running out of attys. I've found some that on first appearance are the same shape & size, although my original attys are 2.4Ω & the new ones are 1.8Ω.

The batteries in both my pipe & the device these are intended for are identical (18350, 3.7V, 800mAh).

Would I experience any issues?

I'm asking as in the 8 years or so I've been vaping, I've always used parts from the original manufacturer that are intended for the model I'm using (with the exception of when I was using M401 models), so I don't really know much about swapping parts.

Sorry to hijack the thread, I did post this question elsewhere, but I'm unsure if I posted in the right place (ECF has changed considerably since my last regular visits).

 

[NU_FTW]

Please be careful, using the above equation is incorrect. You have to account for the efficiency of the Mod.


You need to know:
The power output
The efficiency of the chipset. (usually between 80% and 95%)
The mods low battery cut off point (usually around 3 volts)
The CDR of the battery. ( I use mooches results rather than manufacturer spec as these are often inflated)

This information should be within the specifications or the instructions that came with the mod.

If you put the above information into the battery drain calculator on steam engine (Battery drain) It will tell you how much current is being drawn from the battery. Make sure that the maximum current draw is below the tested CDR of the battery.



Yep, and there is simply no advantage to building very low resistance coils on a regulated mod. In fact a higher resistance coil with more wraps and more surface area makes much more sense.

no not incorrect. Maybe incomplete. Tell u what throw on multiply resulting amps by 1.2 to account for worry of 80% efficiency and voila close enough