I am trying to understand a personal dilemma. I would like to hook up an automobile headlight bulb to a custom made battery pack. What I don't understand is how amps are related to the circuit. Lets say I took (2) 6volt lantern batteries and wired them in a parallel circuit. Now that would be 12volts correct? So now I know that I have the correct voltage to power the headlamp. Now lets say the headlight bulb is rated a 55watts. So 55/12=4.58. So that means the bulbs require 4.58amps, correct? I know the amperage of the fuse that the headlights came from was a 15amp fuse. I don't understand how to test/ know whether or not the 2 6volts batteries wired in parallel have the proper amount of amperage. Is it as simply as hooking up a multi meter and test the amps of the circuit "shorted"(without the headlight wired up?) or is there more to it? Also can any explain to me exactly what can burn the bulb out, in reference to electrical variables. For instance if I have too many amps running to it? Or if I have 24volts instead of 12? I am very new to electrical engineering and I sincerely appreciate anyone's insight.