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All About The Hardware

Vaporizers: Cartomizers To Coils . . . And Back Again

How do you heat e-liquid until it vaporizes without boiling? Unfortunately, just submersing the heating coil directly into the e-liquid simply doesn't work. The e-liquid must be delivered to the coil slowly, at the same rate that it is vaporized. This is called "wicking", and it is accomplished by placing an absorbent material close to the coil and keeping that material wet with e-liquid as it is vaporized.

If you have read the Our Story section, then you know that the first vaporizer to really perform well was the original KR808D-1 cartomizer. The problem with the original cartomizers is that they are small, completely filled with absorbent material, and serve the two purposes of (1) storing the reserve supply of e-liquid, and (2) delivering the e-liquid to the heating coil in a controlled way. Therefore, most of the room in the cartomizer is taken up by the absorbent material, severely limiting the amount of e-liquid that can be stored (e-liquid capacity).

The first tanks ("clearomizers") to hit the market were a huge disappointment! These second-generation devices enclosed the heating coil in a small metal case and provided a long piece of absorbent material (the "wick") which extended from the coil through the case and out into a surrounding reservoir of e-liquid (the "tank"). This dramatically increased the e-liquid capacity, but there were significant problems with performance. Keeping the wick wet with e-liquid close to the coil was a huge problem! It depended entirely on what is called capillary absorbtion in the wick material, and it just did not work very well. For serveral years, we literally bought and tested one new type of clearomizer after another, just to be very disappointed every time. None of the new tanks performed nearly as well as the good old KR808D-1 cartomizer.

Then, someone came up with a brilliant idea:

1. Punch small holes in the side of a miniature cartomizer.

2. Completely submerse the entire miniature cartomizer in a tank of e-liquid.

3. Position the cartomizer at the bottom of the tank, with a tube running from the cartomizer, through the center of the tank, up to the mouthpiece ("drip-tip").

This revolutionary new design capitalized on the fantastic performance of a cartomizer while allowing the cartomizer to be continuously refilled from the tank through the small holes punched in the side. Drawing vapor out of the cartomizer through the tube actually draws more e-liquid into the cartomizer (thanks in part to Bernoulli's principle). And with the cartomizer placed at the bottom of the tank, gravity ensures that e-liquid remains available to the cartomizer as the e-liquid level in the tank drops with use. Therefore, capillary absorption wicks are not required.

Variations on this basic design are used in virtually all of the newer tanks on the market today. When you purchase a new "coil", "head", "atomizer", etc. for a tank, you're really buying a miniature cartomizer with holes punched in its side. The variations on the design include:

• the number of heating coils used;

• the size and design of the heating coils and the type of metal alloy and the specific process used to make them (resulting in specific operating characteristics and electrical resistance);

• the number, size, and shape of the holes punched in the side;

• the type and compaction of the absorbent material used internally, and how that material is placed relative to the heating coil;

• the path (relative to the heating coils) that the air/vapor takes when entering and exiting, and how that air/vapor flow is controlled; and

• the size (e-liquid capacity) of the tank.

All of these variations have resulted in a very wide range of vaporizer products, with a wider range of performance characteristics, and an even wider range of prices. But the basic design used in all of those products is really the same; a cartomizer with small holes punched in its side sitting at the bottom of a tank of e-liquid.

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Batteries: mAh's . . . More And More Of Them

Since the beginning, back in 2009, almost all batteries used in vaping products have been the lithium-ion type. And most of them have the same features in common:

• over-charge protection;

• short-circuit and over-discharge protection;

• some form of voltage regulation; and

• a switch, either manual (a button) or automatic (activated by drawing air/vapor through the device), which turns the battery, and therefore the entire vaping device, on or off.

The differences are in the overall quality of the construction, the nominal voltage of the battery, and the style, including the asthetic design of the battery as well as the type of connection used between the battery and the vaporizer. The three types (styles) of connections that have survived through the years are "808", "510" and "eGo". The 808 style is used in all variations of the original KR808D-1, but it is not compatible with any other vaping device. It consists of a small male threaded connector on the battery, and a female threaded connector on the vaporizer (cartomizer). Almost all of the newer vaping devices on the market today use either the 510 style or the eGo style, and a large number of devices actually use both of those connection types. The 510 style consists of a small female threaded connector on the battery, and a male threaded connector on the vaporizer. The eGo style consists of a larger male threaded connector on the battery, and a female threaded connector on the vaporizer.

But the most important difference in batteries is the mAh rating, and this rating has increased over the years from about 180 mAh in the beginning to over 3000 mAh in the newer batteries on the market today. So, what is the mAh rating? "mAh" stands for "milli-Amp-hours". It is simply a measure of the amount of electrical energy that can be stored in the battery and used to vaporize the e-liquid. The KR808D-1 battery is rated at 280 mAh. This means that it can supply 280 milli-Amps of electricity (electric "current") for a period of one (1) hour.

All vaping devices use the simplest form of electrical circuit, called a "direct-current resistive circuit". This type of circuit is governed by Ohm's Law, which states that the current (in "Amps") is equal to the voltage (in "Volts"), divided by the resistance (in "Ohms").

I = V / R

where "I" is the current in Amps, "V" is the voltage in Volts, and "R" is the resistance in Ohms

The KR808D-1 battery operates at a nominal 3.7 Volts, and the KR808D-1 cartomizer has a resistance of about 1.9 Ohms. By dividing 3.7 Volts by 1.9 Ohms, we find that the KR808D-1 will require about 1.947 Amps, or 1947 milli-Amps to operate. By then dividing the 280 milli-Amp-hour capacity by the 1947 milli-Amp current requirement, we find that the KR808D-1 battery is capable of about 0.14 hours, or 8.6 minutes, or 518 seconds of continuous operation. If each puff takes 3 seconds, a fully-charged KR808D-1 battery should provide about 173 puffs before needing to be recharged. The average vaper will take between 200 and 600 puffs per day (and evening), so a KR808D-1 user will need two (2) to four (4) fully charged batteries per day.

Let's do the same calculations for a GreenSound eGo II Mega Kit. The eGo II battery is rated at 2200 mAh, and operates at a nominal voltage of 3.8 Volts. The resistance of the H2S coil is 1.8 Ohms. Dividing 3.8 Volts by 1.8 Ohms yields a current requirement of 2.111 Amps, or 2111 milli-Amps. By then dividing the 2200 milli-Amp-hour capacity by the 2111 milli-Amp current requirement, we find that the eGo II battery will power the H2S coil for about 1.04 hours, or 62.6 minutes, or 3752 seconds of continuous operation. Again at 3 seconds per puff, a fully charged eGo II battery should provide about 1250 puffs before needing to be recharged, or over seven times more than the KR808D-1. So a single eGo II battery will support the average vaper for two (2) to six (6) days before needing to be recharged.

You can see from these examples, that a higher mAh rating means that you will get more puffs out of your ecig before it needs to be recharged. And since lithium-ion batteries can be recharged a limited number of times before needing to be replaced, a higher mAh rating also means that a battery's lifetime will be longer because it will need to be recharged a fewer number of times.

Some of the newer ecig batteries have ratings of more than 3000 mAh. But some of the newer vaporizers, especially sub-ohm devices (discussed in Sub-Ohm: A New Way To Vape), require as much as 20 Amps, or 20000 milli-Amps, of current to operate. So the bottom line is that you should make sure that your battery's mAh rating is adequate to support your vaporizer's current requirement for the amount of time that you want to vape between re-charges.

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Batteries: Watts . . . Its Really About The Power

Another important characteristic of vaping devices is the amount of power provided to the coil to vaporize the e-liquid. The amount of power provided to the coil determines the temperature at which the coil operates. Generally, more power provided to the heating coil results in a higher coil temperature which results in the production of:

• a higher volume of vapor;

• a denser vapor;

• a more intense flavor (from the flavoring ingredients); and

• a much more intense delivery of the nicotine (if the e-liquid contains nicotine).

And different e-liquids (PG/VG Ratio, Flavoring Type and Strength, Nicotine Concentration, Etc.) will vape differently at different temperatures. So being able to control the power that is provided to the heating coil provides much more control of the vaping experience overall.

Power (in "Watts") in a direct-current resistive circuit is defined as (equal to) the current (in "Amps") times the voltage (in "Volts").

P = I * V = (V / R) * V = V^2 / R

where "P" is the power in Watts, "I" is the current in Amps, "V" is the voltage in Volts, and "R" is the resistance in Ohms

For the KR808D-1: P = 3.7 Volts * 3.7 Volts / 1.9 Ohms = 7.2 Watts

For the eGo II Mega Kit: P = 3.8 Volts * 3.8 Volts / 1.8 Ohms = 8.0 Watts (About 11% More Power)

As shown above, the definition of power simplifies such that the power (in "Watts") is equal to the voltage (in "Volts") squared, divided by the resistance (in "Ohms"). As the voltage increases the power increases exponentially, and vice versa. So small changes in the output voltage of the battery can have a dramatic effect on the performance of the vaporizer. For this reason, most of the newer batteries on the market today have some form of output voltage control.

The simplest of these are just variable voltage batteries where the output voltage of the battery can be set directly, with either a dial setting or a digital setting. The newer batteries usually allow the power in Watts to be set directly, but all the battery does with this setting is to measure the resistance of the coil and then change the output voltage appropriately to provide the set amount of power to the coil.

Most of the newer batteries also have a temperature control ("TC") feature. TC is based on the fact that the electrical resistance of a metal generally increases as the temperature of the metal increases. Some metal alloys (kanthal) have a very small resistance change as their temperature increases (low "temperature coefficient"). Other metal alloys (nickel, titanium, stainless steel) have a much larger resistance change as their temperature increases (high "temperature coefficient"). The temperature control feature primarily uses heating coils made from metal alloys with a high temperature coefficient (nickel, titanium, stainless steel), but some of the newer box mods are capable of temperature control with coils made with kanthal. When setting up the TC mode, the user "locks-in" the base resistance of the coil (resistance at room temperature), sets the temperature coefficient of the coil, and sets the coil temperature desired. Then, when turned on, the battery continuously (many times per second) monitors the coil resistance and calculates the temperature of the coil from the base resistance and temperature coefficient. It then adjusts the output voltage of the battery to provide more or less power, and, therefore, to raise or lower the coil temperature to the set value.

Temperature control provides a number of significant advantages over both the variable voltage and the power control features.

Avoiding Dry/Burnt Hits - All vapers have experience the dreaded "burnt hit". It happens when the e-liquid in the absorbent material surrounding the heating coil is vaporized faster than it is replaced. The absorbent material dries out, the coil temperature increases, and the absorbent material starts to burn. Usually, we forgot to refill our cartomizer or tank, or we took too many drags on the ecig with it upside down. But when it happens, it's awful. The taste is awful, and typically the coil is ruined and must be replaced. But with temperature control, the coil temperature is not allowed to increase and the coil is saved. And instead of producing that awful burnt taste, it just stops producing vapor.

Longer Coil Life - All heating coils, and the absorbent material surrounding them, have a limited life. But that lifetime can be easily shortened by "over-driving" the coil, or operating it with too much power, and therefore at too high of a temperature. The temperature control feature ensures that the coil is always operating at the optimum power and temperature level for the longest life possible.

Battery Life - It has been estimated that most variable voltage and power control vapers tend to over-drive their coil, using about a third (33%) more power than necessary. The temperature control feature prevents over-driving, and therefore saves that wasted energy.

So the power supplied to the heating coil can be adjusted (controlled) using the variable voltage, power control, or temperature control features. But in all cases, it is the output voltage of the battery that is really being adjusted or controlled.

But the most significant change in vaping hardware uses another way to increase the power supplied to the coil. For an in-depth discussion of "sub-ohm" vaping:

PLEASE READ: Sub-Ohm: A New Way To Vape

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