Oscilloscope Trace

Here's what happens when the lighter reaches temperature and pops out, breaking the circuit to the "dew heater". There are actually a number of spikes due to the lighter not switching off all at once, but the final disconnect results in a spike of about 37 volts! Note too how the voltage going to the mount is not at the battery voltage due to the load of the heater and the losses in the cable that it's pulling the current through.