Okay so I'm sort of lost on this topic. Personally I have a smok T-Priv 3 with 3 Samsung inr18650 30q. I'm currently using a 0.4 ohm coil and run in between 45-75W. I have a 0.12 ohm coil and want to use it but don't know if it's safe to run at 75W? I tried the ohms calculator but can't seem to completely understand. It says at 100W I'd be running it at 6v and 28 amps which seems to be over the battery capacity. Can somebody dumb this down for me?
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Ohm's Law only applies to the coil side of the regulator on a regulated device. Read this for more info Calculating battery current draw for a regulated mod | E-Cigarette Forum
Lots more info in his other blogs also
Lots more info in his other blogs also
First step, ignore the amps shown on the screen. That is output amps (from the device to the coil) and is unrelated to the input (battery to device) amps that you need to concern yourself with. On a regulated device, the ohms don't matter so much. It's either within the device's operational range, in which case it will fire, or not, in which case it won't. Amp draw on a regulated device is determined by the watts setting, not the atomizer ohms (it's only in mechanical mods, where the wattage, and thus, the amperage, is determined by atomizer resistance/ohms, that ohms are related to battery safety.)
Amp draw on a regulated device is equal to watts/volts. So you can see that as the battery voltage goes down, amp draw goes up. The highest amp drain, then, will be when the batteries are near the device's low-voltage cutoff mark. Usually around 3.0v per cell. So when we're calculating battery drain, we assume the worst case, 3 volts, for safety's sake. So in a dual-cell device like the T-Priv, that would be 6 volts*. At 75w, you're looking at 75/6 = 12.5 amps (each cell).
*(6v assumes the cells are in series. If they're in parallel, then it's still the same 3 volts as with a single cell, but then the amp load is "shared" between cells, so instead of 12.5A each cell, you're looking at 25 amps, shared between two cells, which works out the same in the end.)
You are using a "Regulated" PCB Computer Controlled Mod, meaning there is a control board between the coil/coils and the batteries, the resistance only comes into play with a Regulated Mod in these 2 instances:
1) Mod PCB Computer reads the coil resistance (Ohms), if Ohms are within the programmed minimum (generally 0.1 to 0.15 Ohms) and maximum (generally about 2.5 to 3.0 Ohms), store resistance reading, move to step 2 if "A Okay", if below the minimum programming, kick out error code to user and refuse to fire
2) If minimum resistance is above minimum and good to fire, take resistance reading, check watts set setting, calculate needed voltage to reach set watts, then fire.
Most multi-battery mods use a "Series Battery Configuration", think a tube style flashlight, each battery is .... up to the one above it in a series. This configuration, Maximum Available Voltage = Voltage of Single Battery X Number of Batteries, CDR Amp Limits of a single battery, and MaH rating of a single battery. Li-Ion 18650 batteries, the voltage charge ranges between 4.2v full charge to about 2.5 to 3.0v minimum, most current mods, lowest before errors is about 3.2v. 3X Batteries, those ratings of the battery series become, 12.6v full charge (4.2v X 3), and 9.6v lowest (3.2v X 3), 15 to 20 amps CDR, 3000Mah.
Ohms Law which helps us calculate such figures as Amp draw, watts power output, voltage, even resistance in Ohms, has within the law many many formulas to do just that. Most Ohms Law calculators generally just need 2 of the 4 variables to calculate the other two. With Vaping 2 formulas are used the most
Mechanical/Unregulated
Volts/Resistance=Amps
4.2v/0.15ohms=30amps as example
Regulated Like your Mod you can do the needed formula one of two ways with just a calculator
Watts Set/Lowest Available Voltage/Mod PCB Efficiency Rating (this ranges from 75% to 97% depending on the control board, but safe guess average is 90% or 0.9 for calculations)=Maximum Amps
Using Variables you posted above
100 Watts Set/9.6v/0.9=11.5741amps as example
Second way to break it down per battery
Watts Set/#of Batteries=Watts Per battery
100 Watts Set/3 Batteries=33.33 watts per battery
33.33watts/3.2v/0.9=11.5729amps
Okay, great info thanks everybody. Now I can vape comfortably. So resistance doesn't matter? All I really need to know is watts/volts=amp draw. In a 3 battery mod (2 run parallel) I would use an equation like, 1/3watts/3.2v=amps drawn per cell or watts/9.6v=amps drawn per cell. As long as I'm under 15amps drawn per cell I should be good?
Very close. The missing factor is that the board in a regulated mod isn't entirely efficient, so you lose a bit of power that way. It's usually advised to assume a 90% board efficiency, so you want to stay under 13.5 A per cell with a 15 A battery: 15 A x 0.9 = 13.5 A. Some people simplify the equation by using a cutoff of 3 v rather than 3.2 v to factor in the board efficiency - I think that's what @bwh79 did above.
Ohh okay, so really I'm only safe to go up to 125w. 125w/9.6v=13.02amps
Yes, you've got it.
Just one thing about the word 'safe'. We're using these batteries in ways they weren't intended, so it's a bit iffy to proclaim that something is safe. It's important to remember that you need to make sure your batteries are in good condition physically - no nicks or tears in the wrapper, etc. - and that CDR (the 15A) drops with use and age (and with abuse), so you can never be absolutely certain what a battery can handle. I guess our 'best practices' are to stay under the CDR (preferably with a safety margin that increases with age) and keep an eye out for batteries heating up or doing anything odd or unexpected. To be fair, the likelihood of thermal runaway (battery explosion) is very low as long as you're not abusing your batteries, but there's no way to bring it down to zero. And there's my rant for the day...
Vape on!
The "Divide Watts by 3" convention is used to help nervous newbies get in the neighborhood of how much power they can expect out of their batteries.
Factoring in board efficiency is important, especially when the divide by three convention gets close to the limit.
Are you using a single, dual, or triple battery mod? In the interests of keeping things simple:
WATTAGE PER SINGLE BATTERY:
20W-45W:
Samsung 18650 30Q, 3000 mah 15/20 amp CDR
Sony 18650VTC6 3000mAh 15/20 amp CDR
20W-60W:
LG 18650HG2 3000mah 20 amp CDR
LG 18650HE2 2500 mah 20 amp CDR
Samsung 18650-25R, 2500 mah 20 amp CDR
Sanyo UR18650NSX, 2500 mah 20 amp CDR
Sony 18650VTC5, 2600 mah 20 amp CDR
Sony 18650VTC4, 2100 mah 23 amp CDR
AW 18650 3000 mah 20 amp CDR
30W - 75W:
LG 18650 HD4 2100 mah 25 amp CDR
LG 18650 HD2 2000 mah 25 amp CDR
Sony 18650VTC5A, 2500 mah 25 amp CDR
60W - 90W:
LG18650HB6 1500mah 30 amp CDR
LG18650HB2 1500mAh 30 amp CDR
LG18650HB4 1500mAh 30 amp CDR
Battery Basics for Mods: The Definative Battery Guide for Vaping
If you use a good quality 15 amp CDR battery like the Samsung 30Q or Sony VTC6, then you are good up to 45 watts per battery; 90 watts using two; 135 watts for three batteries.
If you use a good quality 20 amp CDR battery like the LG HG2 or Samsung 25R then you are good for 60 watts per battery. If using a 2-battery regulated mod, your good for 120 watts as you have two batteries. If you are using a 3-battery mod, you're good for 180.
If you use a single 25 amp CDR battery like the Sony VTC5A, then you are good for 75 watts per battery, 150 watts for two batteries, and 225 watts with three.
If you use a single 30 amp CDR battery like the LG HB6 you are good up to 90 watts; with a pair of 30 amp CDR batteries you could safely do 180 watts.
If you use a good quality 20 amp CDR battery like the LG HG2 or Samsung 25R then you are good for 60 watts per battery. If using a 2-battery regulated mod, your good for 120 watts as you have two batteries. If you are using a 3-battery mod, you're good for 180.
If you use a single 25 amp CDR battery like the Sony VTC5A, then you are good for 75 watts per battery, 150 watts for two batteries, and 225 watts with three.
If you use a single 30 amp CDR battery like the LG HB6 you are good up to 90 watts; with a pair of 30 amp CDR batteries you could safely do 180 watts.
WATTAGE PER SINGLE BATTERY:
20W-45W:
Samsung 18650 30Q, 3000 mah 15/20 amp CDR
Sony 18650VTC6 3000mAh 15/20 amp CDR
20W-60W:
LG 18650HG2 3000mah 20 amp CDR
LG 18650HE2 2500 mah 20 amp CDR
Samsung 18650-25R, 2500 mah 20 amp CDR
Sanyo UR18650NSX, 2500 mah 20 amp CDR
Sony 18650VTC5, 2600 mah 20 amp CDR
Sony 18650VTC4, 2100 mah 23 amp CDR
AW 18650 3000 mah 20 amp CDR
30W - 75W:
LG 18650 HD4 2100 mah 25 amp CDR
LG 18650 HD2 2000 mah 25 amp CDR
Sony 18650VTC5A, 2500 mah 25 amp CDR
60W - 90W:
LG18650HB6 1500mah 30 amp CDR
LG18650HB2 1500mAh 30 amp CDR
LG18650HB4 1500mAh 30 amp CDR
Battery Basics for Mods: The Definative Battery Guide for Vaping
Welcome and glad you joined.
Good luck and above all be safe.
Might like to read:
http://best-e-cigarette-guide.com/e...cigarettes/sub-ohm-vaping-perks-and-problems/
What is Sub Ohm Vaping? Our Sub Ohm Vaping Guide & Tips
https://spinfuel.com/sub-ohm-vaping/
Battery safety
Care and Use of 510, eGo and Variable Voltage Batteries
https://www.e-cigarette-forum.com/forum/blog-entry/7-information-resources-for-your-first-rba.4454/
https://www.e-cigarette-forum.com/forum/threads/ecf-sub-ohm-advisory.562106/
it wont matter much the resistance in a regulated mod as your Smok, the 100w 28a calculation is for mech mods and thats more of an advanced vape stuff i wont go into it, back to your question think of your wattage as how much ramp up coils take to heat and each build type is different. should cover quick base of things
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