Coil build/battery

[Kevin Uckfield]

Hi all. I’m Kevin from the Uk. I’m not new to vaping and have building coils for some time but I’m a little lost.
My previous build on my dripper consisted of 2 coils with a total ohms of 0.1.
I have been advised that going up in ohms will produce less vapour but a stronger flavour.
Today I built 2 coils with 24 gauge wire, total ohms of 0.37 ohms.
The thing that I don’t understand is this:
0.1 ohm coils at 102 Watts drew 3.5v
0.37 ohm coils at 60watts draws 4.8v
So, higher ohms appears to have more drain on the battery. Am I misunderstanding or doing something wrong?
Please help

 

[Izan]

Hi Kevin and welcome,

Those builds draw different amps.
The .1Ω build pulls almost 32 amps.
The .37Ω build pulls barely 13 amps.
The chip in your device delivers those voltages to your builds, but the cells/batteries are not being "asked" to produce those voltages.
The higher the amp draw, the shorter the battery life. Period.

HTH
Cheers
I

 

[greek mule]

calculating battery current draw for a regulated mod

 

[Punk In Drublic]

With a regulated device you have 2 sides to the regulated circuit. An input side (battery) and output side (coil). The input (battery) does not see the resistance of the coil – it only see’s what the regulated circuit is asking in terms of power. So the current draw on the output side will have little effect on battery performance assuming the same power is used (sans extremes!).

The voltage on the output side is assigned based on the resistance of the coil and the set power. This can be calculated as Voltage = √Power x Resistance (take that with a grain of salt for not all devices get this right!)

Current on the output side (coil) can then be calculated as Current = Volts / Resistance.

So if 100 watts was assigned with a 0.5ohm coil the above would equal 7 volts drawing 14 amps. On a 0.2 ohm coil with the same 100 watts this would equal 4.5 volts and 22.3 amps.

The current draw on the input side (battery) is the same should 100 watts be used. This is calculated as Current = Power / Voltage. As the battery voltage decreases, the current increases in order to compensate and meet the power demand.

To calculate the true current draw with a regulated device we need to factor in the device’s efficiency. This is unknown with most devices but a safe guesstimate is 90%. The calculation is done by determining the Watts per Battery, divide by the Voltage per Battery then divide by the efficiency. So 100 watts on 2 cells with fully charged 4.2 volts would be…

100(watts)/2 (batteries) = 50
50/4.2 (volts)/0.9 (efficiency) = 13 amps (per cell)

But this changes as the battery voltage drops which is why we use the cut off voltage of the device to determine the correct CDR of the battery. The above with a 3.2 average cut off voltage

100/2 = 50
50/3.2/0.9 = 17.3 amps (per cell)

 

[greek mule]

What device -How many batteries ?
CDR of your batteries?
Are they brand name?Sony/Murata -Sanyo/Panasonic-LG -Samsung?

 

[Kevin Uckfield]

Device reuleaux RX300
4 x 18650 efest 2500 mah 35A 3.7v
Dripper is drop dead
Wire Kanthal A1 24 AWG

Batteries show 4.2v fully charged

 

[Kevin Uckfield]

Hi Kevin and welcome,

Those builds draw different amps.
The .1Ω build pulls almost 32 amps.
The .37Ω build pulls barely 13 amps.
The chip in your device delivers those voltages to your builds, but the cells/batteries are not being "asked" to produce those voltages.
The higher the amp draw, the shorter the battery life. Period.

HTH
Cheers
I

Oh. So if I stay at .10 the batteries last longer. Thanks for that. Much appreciated

 

[Ben Killeen]

Oh. So if I stay at .10 the batteries last longer. Thanks for that. Much appreciated

No, they last longer with the .37 build

 

[Punk In Drublic]

Oh. So if I stay at .10 the batteries last longer. Thanks for that. Much appreciated

That is incorrect. As I stated in my above post the resistance has little effect on battery life with a regulated device. Your power setting is what determines how long the batteries last. The higher the power, the shorter the battery life.

Also to note that Efest grossly exaggerates their battery ratings. Your batteries are not 35amps – do not know what CDR they are. I would highly suggest you acquire 20 to 30 amp batteries from either LG, Samsung or Sony.

 

[sonicbomb]

The balance of amps and volts delivered to the coil is calculated by the regulator chip in the mod to deliver the total wattage you have selected (amps x volts = watts). A low resistance coil will require more amps and less volts, a high resistance coil will require more volts and less amps. This is on the atomizer side of the regulator.

On the battery side of the regulator, the chip will draw the power it needs from the batteries. The batteries can be thought of as a pool of watt hours that the chip draws on as required. The actual balance of amps and volts is determined by the chip based on the remaining voltage in the batteries, as the voltage in the battery decreases the chip will draw more amps. Hence why a battery of the correct CDR needs to be chosen for a selected maximum wattage.

The point is that the chip takes care of all this regulation for you.
The majority of the numbers on the screen of a regulated mod are of no importance and do little but cause confusion. Its like putting all the readouts you would expect to see in a race car like manifold pressure, oil temperature and fuel pump pressure in a soccer mum van.

A very low resistance coil will drain your battery faster because it is less efficient as low resistance coils are inevitably also high mass with slower ramp up and down times.
If you want to increase battery life build a coil with maximum surface area and the minimum mass, it will require less over-all power.

 

[BrotherBob]

Hi all. I’m Kevin from the Uk. I’m not new to vaping and have building coils for some time but I’m a little lost.
My previous build on my dripper consisted of 2 coils with a total ohms of 0.1.
I have been advised that going up in ohms will produce less vapour but a stronger flavour.
Today I built 2 coils with 24 gauge wire, total ohms of 0.37 ohms.
The thing that I don’t understand is this:
0.1 ohm coils at 102 Watts drew 3.5v
0.37 ohm coils at 60watts draws 4.8v
So, higher ohms appears to have more drain on the battery. Am I misunderstanding or doing something wrong?
Please help

Welcome and glad you joined.
Might like to read:
Sub-Ohm Vaping Explained – Pros and Cons of a Controversial Trend
Calculating battery current draw for a regulated mod | E-Cigarette Forum
Index | E-Cigarette Forum
Best 18650 Battery Explanation!
Vape Battery Safety: Will You Marry Me? | Mt Baker Vapor
A Guide to Safe Charging - The Complete Guide to E-Cig Safety
Vaping 101: Battery Safety
7 Best Practices to Keep Your Charge

 

[Baditude]

WATTAGE PER SINGLE BATTERY on REGULATED MOD:
(Total wattage doubles using 2 batteries; Triples using 3 batteries.)

Up to 45W:

Samsung 18650 30Q, 3000 mah 15 amp CDR

Sony 18650VTC6 3000mAh 15 amp CDR

​

Up to 60W:

LG 18650HG2 3000mah 20 amp CDR

LG 18650HE4 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

Up to 75W:

LG 18650 HD4 2100 mah 25 amp CDR

LG 18650 HD2 2000 mah 25 amp CDR

Samsung 18650-24S, 2500 mah 25 amp CDR

Sony 18650VTC5A, 2500 mah 25 amp CDR

​

Up to 90W:

LG18650HB6 1500mah 30 amp CDR

LG18650HB2 1500mAh 30 amp CDR

LG18650HB4 1500mAh 30 amp CDR

Samsung 18650-20S 2000mah 30 amp CDR