Ignites at a constant voltage of 4 to 6 amps (DC) for a maximum usage time of 2 hours per day. Luckily I smelled burning plastic and stopped using it. I burned my finger at the tip just looking at it. burned my finger badly. I think it gradually started to melt since I first used it. The flat tip doesn't always sit properly in the shaft and all of the load was on the edge of the tip. I checked it out and found it almost impossible to get the flat tip plugged into a 12V outlet perfectly every time. I've had them for a few months now and there doesn't seem to be a way to get a refund on amazon after a few months. If my car caught fire, someone would be stitched up immediately. Very, very bad design.