Terminology, mechanical mods
The "electronic cigarette" was first conceived in 1963 by Herbert A. Gilbert. His device was used with liquid and simulated the smoke typical of traditional cigarettes. The technology was just not up to par at that point. The liquid also did not use nicotine at that point.
The technology was popularized in 2003 by Chinese pharmacist Han Lik. He set out to design an "electronic cigarette" after his father died from lung cancer. His was the first "electronic cigarette" to use liquid that contained nicotine.
It still took several years for the "electroic cigarette" to make it into the hands of the general population. In the meantime, many people that heard about this invention designed their own versions: and mechanical mods were born. The earliest versions were nothing more than pipes cut to a length to accommodate a battery, a firing mechanism, and a converted bulb system that took on the look of the filter portion of a regular cigarette (a cartridge atomizer, or cartomizer).
While innovative, these were risky. At the time, users were putting these together with unprotected batteries. Stories about explosions, while rare, were still an occasion. That usually happened when liquid leaked into the battery compartment ... and with no protection for the battery, you ended up with over-heating, shorts, firest and explosions.
Electronics helped and that's where the "penny circuit" became part of the mechanical mod kit. The penny circuit is a small board that is about the same diameter as a penny. It was used at the top of the battery between the positive post and the atomizer connector. If the penny circuit detected high heat loads, it essentially "shorted" itself out and shut down the connection, protecting the user from riskier alternatives. These were widely used when ICR batteries were the norm.
Today we have much safer battery technologies such as IMR and INR batteries and these penny circuits are no longer needed. Using a mechanical mod today is much safer with most designed so that leaking liquid cannot get into the battery compartment. The battery tube portions are well vented.
As you progress in your vaping experience, you might want to try out a mechanical mod. They do provide raw pure power directly to the atomizer ... whatever the battery outputs is what gets sent to the coil. Some of the newer 26650 mechanical mods, as an example, can pulse out 60 amps direclty to the atomizer and provide "a hit that feels like a Mack truck".
Mechanical mods are still very basic devices. The core element is a tube that holds a battery. Some are adjustable so that you can use different length batteries. The bottom is usually a firing mechanism that is spring loaded – press it in and the power connection is made, release it and the spring pushes back the firing mechanism breaking the power connnection. The top has a 510 connector, sometimes with an adjustable 510 connector pin. Some have air flow slots to help get air to the atomizer.
Mechanical mods are multi-part systems: you have to supply the battery separately. When the battery no longer retains a charge, you just replace the battery component. In a lot of respects, this is why mechanical mods are so ornate. The hardware can be personalized to suit the user. It's not disposable, it stays with you: just replace the battery as needed. They are also reasonably inexpensive: there are no electronics, it's entirely mechanical.
As you look at mechanical mods, you will need to get familiar with the replaceable battery terminology. There are essentially four diameters available. Here's how to interpret the numbers of the batteries:
- 14000 series, like the 14500. The first two digits '14' represent the diameter in millimeters (14 millimeters). The second two digits represent the height in millimeters (50 millimeters). The last digit is not used.
- 16000 series, like the 16500 and 16650. 16 millimeters in diameter, 50 or 65 millimeters in height.
- 18000 series: 18340, 18350, 18490, 18500, and 18650. All 18 millimeters in diameter.
- 26000 series: 26650 is 26 millimeters in diameter and 65 millimeters in height.
No electronic cigarettes should be using ICR battery technology. ICR is not "high-drain" and under the constant use and repeated short firings of vaping, will deplete very quickly. The only two technologies worth considering are IMR and INR. IMR is the most common and least expensive. INR is fairly rare (i've seen 18650 INR sell for over $900 per battery) – and INR is also the safest of all technologies.
If you need more information on batteries, do a Google search for "battery university" ...