If you use cartomizers with a brass, aluminum, or steel drip tip (T-Tip, Zip Tip, etc.) make sure that the drip tip does not contact the wire that runs up the core of the cartomizer. Sometimes, where that wire makes its U-Turn, it will short out on the drip tip. It happened to me this morning, my drip tip got very hot but the carto did not! Luckily, I figured out what was happening before I did any damage to my battery. So, be warned!