All brands of electronic cigarettes will consist of 2 to 3 main parts: a battery, a tank and the coil that sits within the tank.
The batteries are typically lithium ion cells. A lot of devices today will use what is called an 18650 battery. The battery got it’s name simply from it’s dimensions. Each cell uses either a protection circuit or utilizes safe chemistry (IMR) to prevent and avoid failures. Most e-cigarettes are controlled by a microprocessor in the battery which regulates the amount of power or wattage that the device can safely put out. The majority of devices have a button in order to activate the battery and send power to the 2nd part of the e-cigarette which is the coil. Battery life is estimated using the milliamp hour rating(mAh) and can range anywhere between 300mah to 3000mah. Each battery is typically rated to have a useful life span of approx 300 charge cycles.
The coil can be considered the heart of an e-cigarette and its function is to heat the e-liquid and turn it into vapor. A coil includes a separate tank in order to house the e-liquid. While there are many types of coils they all have the same basic architecture. The coil consists of kanthal, nickel or stainless steel wire wrapped in organic cotton. When the device is activated, power flows from the battery into the coil, heating it up and vaporizing the liquid that sits in the cotton. As the user draws on the device air flows in from intakes to mix with the vapor which is then inhaled.
E-liquid is comprised of 3 or 4 ingredients; Propylene Glycol(PG), Vegetable Glycerin(VG), food grade flavorings, and can contain nicotine in various amount measured in milligrams.