Just to chime in a little...Most of the "horror" stories of batteries blowing up can be traced to user error more than any other reason. Improper charger, "well, it looked like it was the same", improper charging environment, like left in a car attached to a charger in the broiling sun during the summer, and there are other examples.
That said, the lithium based batteries used in e-cigs, mods as well as "stick" batteries, are capable of producing very high amount of power for varying amounts of time. Some common sense, some basic knowledge of batteries and using quality batteries and chargers can probably eliminate most of the possibilities of things going wrong.
Just think about how many items contain lithium batteries today, cell phones, laptops, flashlight, medical equipment used in hospitals, airplanes and the list goes on and on. Statistically, something will go wrong with a battery somewhere, somehow, no matter how careful you may be, but the statistics show it its an extremely rare event.
