I'm confused

[AVPENOOB]

Lets say I build a dual coil and screw it on the 2-in-1 ohm and voltage meter and it reads 0.5 ohms, what is a good battery to use?

I was planning to use a Efest IMR 18650 battery with an amp limit of 10A.

Is this safe? I don't understand what's safe or not.

 

[Dakota Jim]

not that battery - you need a 30amp rated battery - you need to stay above 1.4 ohms on a single coil until you completely understand ohms law and battery safety

And for a better understanding of batteries and their safe use we have

Baditudes Battery Blog part 1

Baditudes Battery Blog part 2
​

 

[AVPENOOB]

not that battery - you need a 30amp rated battery - you need to stay above 1.4 ohms on a single coil until you completely understand ohms law and battery safety

And for a better understanding of batteries and their safe use we have

Baditudes Battery Blog part 1

Baditudes Battery Blog part 2
​

how about if I build a single coil unit measuring at 1.5 ohms and use a MNKE IMR 18650 battery with an amp limit of 25A?

 

[Wingsfan0310]

I (amps) = voltage /resistance so 4.2/.5= 8.4amps

It should be safe, but you don't have much headroom. I probably wouldn't do it with that battery, I'd go with with an IMR with a higher amp rating.

Cheers,
Steve

Edit You really shouldn't be messing with mechs and rebuildables without an understanding of ohms law and battery safety

 

[AVPENOOB]

I (amps) = voltage /resistance so 4.2/.5= 8.4amps

It should be safe, but you don't have much headroom.

Cheers,
Steve

even though its a dual coil, you just calculate it like that ( volt / resistance ) ?
then i can build a dual coil at .5 ohms and just get 30A batteries for more headroom?

 

[North_Co]

You should be safe. For the future, you can always calculate amp draw when you know your voltage and resistance here Watts - volts - amps - ohms conversion calculator

18650's, properly charged, will start off putting out 4.2-4.3 volts, so that is what you should put in for voltage. Stay on the safe side and put in 4.3v. Putting in 4.3 for voltage and 0.5 ohm for resistance, we get 8.6 amps being drawn and 36.98 watts going through that coil, which is below the 10-amp limit for the efest IMR's.

VaporAddict on reddit also put together a very nice chart of the more popular batteries' continuous amp limits:
http://i.imgur.com/prP1TYX.png

Edit: I suck with forum tags, sorry. Also, if you're metering the built atomizer/head, you calculate it the same. Now, if you have two coils measuring 0.5 ohms each, then you're in the "need bigger battery" range, since your build will actually be 0.25 (0.5/2)

 

[crxess]

even though its a dual coil, you just calculate it like that ( volt / resistance ) ?
then i can build a dual coil at .5 ohms and just get 30A batteries for more headroom?

Why are you stuck on .5ohm? Someone tell you it is magic?

You will get a better vape off a well built coil in the 1.0+ range. It may not be as foggy, but it will be better.
Who knows, you may keep your face.

 

[Dakota Jim]

make sure each coil is exactly the same ohms (1 ohm in this case) otherwise it won't fire correctly

if you feel the battery tube or the button on your mech getting hot at all - stop right away

be careful, please

 

[AVPENOOB]

You should be safe. For the future, you can always calculate amp draw when you know your voltage and resistance here Watts - volts - amps - ohms conversion calculator

18650's, properly charged, will start off putting out 4.2-4.3 volts, so that is what you should put in for voltage. Stay on the safe side and put in 4.3v. Putting in 4.3 for voltage and 0.5 ohm for resistance, we get 8.6 amps being drawn and 36.98 watts going through that coil, which is below the 10-amp limit for the efest IMR's.

VaporAddict on reddit also put together a very nice chart of the more popular batteries' continuous amp limits:
http://i.imgur.com/prP1TYX.png

Edit: I suck with forum tags, sorry. Also, if you're metering the built atomizer/head, you calculate it the same. Now, if you have two coils measuring 0.5 ohms each, then you're in the "need bigger battery" range, since your build will actually be 0.25 (0.5/2)

you helped me understand this. cheers to you!

 

[AVPENOOB]

Why are you stuck on .5ohm? Someone tell you it is magic?

You will get a better vape off a well built coil in the 1.0+ range. It may not be as foggy, but it will be better.
Who knows, you may keep your face.

it was just an example. i ordered some pre made coils at 1.5 ohms anyways. i just wanted to understand what is safe and not.

 

[AVPENOOB]

make sure each coil is exactly the same ohms (1 ohm in this case) otherwise it won't fire correctly

if you feel the battery tube or the button on your mech getting hot at all - stop right away

be careful, please

so if im building a 1 ohm dual coil, i should measure each separately and be getting 2 ohms on each?

 

[Wingsfan0310]

To calculate the resistance of 2 coils wired in parallel:
Req = 1/{(1/R1)+(1/R2)}

Edit: To answer your question two 2 ohm coils wired in parallel will be 1 ohm total resistance.

 

[Stosh]

Lets say I build a dual coil and screw it on the 2-in-1 ohm and voltage meter and it reads 0.5 ohms, what is a good battery to use?

I was planning to use a Efest IMR 18650 battery with an amp limit of 10A.

Is this safe? I don't understand what's safe or not.

A quick note on safe and headroom, the numbers you posted for amp limit and ohms are "best case" The 0.5 ohms can change slightly once juice is applied, and / or when the coil is heated. The 10 amp limit of the battery is for one that is brand new, no increases in internal resistance, passed quality control with flying colors (not built on a Monday or Friday...)

Engineers will normally design with a double the numbers of maximum stress at the very minimum. If a bridge is rated for 5 ton trucks, design it to stand up to at least 10 tons, if a auto brake pad is designed for an operating max temp, make it stand up to at least double. So if you're looking to run 8.6 amps, a battery designed for at least 17.2 amps would be your minimum. And that's assuming the battery is in good shape, and the specifications are not an exaggeration (like what they do with mah ratings all too often)

 

[danimal40]

how about if I build a single coil unit measuring at 1.5 ohms and use a MNKE IMR 18650 battery with an amp limit of 25A?

yes that is a good battery to use for all your coils 1+ or sub ohm. also efest makes a 18650 30a which is what I use

 

[AVPENOOB]

A quick note on safe and headroom, the numbers you posted for amp limit and ohms are "best case" The 0.5 ohms can change slightly once juice is applied, and / or when the coil is heated. The 10 amp limit of the battery is for one that is brand new, no increases in internal resistance, passed quality control with flying colors (not built on a Monday or Friday...)

Engineers will normally design with a double the numbers of maximum stress at the very minimum. If a bridge is rated for 5 ton trucks, design it to stand up to at least 10 tons, if a auto brake pad is designed for an operating max temp, make it stand up to at least double. So if you're looking to run 8.6 amps, a battery designed for at least 17.2 amps would be your minimum. And that's assuming the battery is in good shape, and the specifications are not an exaggeration (like what they do with mah ratings all too often)

thumbs up for safety! i will get a 25amp battery to be safe.

 

[AVPENOOB]

yes that is a good battery to use for all your coils 1+ or sub ohm. also efest makes a 18650 30a which is what I use

i will look into those batteries as well!

 

[danimal40]

they are 8 bucks here
18650 Flat-Top 1600mah Battery - Mt Baker Vapor - Electronic Cigarettes

plus they have cheap juice

 

[AVPENOOB]

they are 8 bucks here
18650 Flat-Top 1600mah Battery - Mt Baker Vapor - Electronic Cigarettes

plus they have cheap juice

thanks!
i'm not into buying juice online because i want to at least smell it to see if i'll like it or not.

 

[crxess]

it was just an example. i ordered some pre made coils at 1.5 ohms anyways. i just wanted to understand what is safe and not.

gotcha! We have a battery chart Put together by Steam Turbine and Baditude that does a good job of covering Batteries and safe usage.
http://www.e-cigarette-forum.com/forum/apv-discussion/510390-fyi-subohm-vapers.html#post11777440

An excellent rule of precaution is staying above .5ohms as it leaves little room for any mistakes. I have used pre-made 1.8ohm with very good results at .85ohms finished. Nice thing is the consistency of the coils.
My Sub ohm builds use MNKE 30a/60a Batteries.
The 20a & 30a Batteries are an excellent choice for performance and safety. Best for avoiding over stressing the battery.

 

[Jawden]

dude, i mentioned this in the other thread. hahaha.

click here --> Ohm's Law Calculator

all you have to input is "Voltage" and "Resistance" - (the two things your 2-in-1 ohm meter tells you...i gotta get me one of those...)

to be safe, i always input "4.2" in the "Voltage" box.

Voltage is the output of a freshly charged battery with no voltage drop. BUT! i just remembered you have the 2 in 1 ohm/volt meter so you can be more precise when inputting voltage!

and next,

Resistance, which is, in your case, "0.5"

click "calculate" and the site/formula will tell you the ampere and wattage output.

i dont mean to be snide with my elaboration in this post. (hope you didnt take it that way)

just want to be precise with instructions to help clear up your confusion.

hope you figure it out!