voltage has no part in the equation, being 6,12,24 volts operating system has nothing too do with the head light heat,, wattage is the killer most globes are 55/60 .... 55 low 60 high, your new style( plus)+ globes are still 55/60 w but offer up too 80% more light,,, running a true 100 watt globe is possible but with the heat stress on the wires not advisable, then if your using a plastic lens that will melt/discolour very quick..... in any electrical repairs or mods a cheap test light is a handy tool.