Well, how long is a piece of string? One example is a 1000 mAh pod system will last the average user a full day, however every battery/coil combo will vary wildly. External 18650 battery mods will generally be the longest lasting in terms of battery life.
If you are interested in learning the lifetime of a battery. Anything under 1000 mAh usually lasts around 6 months. Anything 1000 mAh or bigger normally lasts about a year. Of course this varies depending on usage, how much you vape and what power you run the device at etc.
510 batteries are the most common batteries for vape devices. They vary in size, in power and if they are built in batteries, or external. The basic concept of how to use one, is thread the tank into the 510 battery. Turn on the battery, and either push a button, or inhale to vape with it. Most 510 batteries can be turned on or off, and the standard way to do that is to press the button 5 times.
Yes and no. If you properly take care of a battery, they are safe. If you are careless, continue to use damaged batteries, get them wet, leave them loose in your bag, yes they can be dangerous.
For internal batteries you just need to make sure it's not damaged, or wet and you should be safe.
For external batteries, you need to check the battery, we recommend at least twice a month. Make sure the wrap on the battery isn't falling off and that the battery isn't dented. Also make sure to never leave a loose battery anywhere around metal as that can cause it to activate, which can severely burn or injure you. It can even start a fire.