The resistance changes with applied voltage AND CURRENT through the ballast. Without knowing the temperature/ resistance/ current curve, you cannot calculate it The stated resistance is cold.
Which is why light bulbs always seem to blow when you first turn the damned things on.
Current inrush in a cold piece of tungsten before it heats up.
Hey wanna hear something funny that happened to me today?
I just did the Bosch relay mod on another one of my Darts.
I tested them out with just battery and they were just fine.
So today I was going to the grocery store in it and started the car for the first time.
Of course I tried the headlights out with full alternator voltage and the driver's high beam gave up the ghost as soon as I turned it on.
Poof.
That's sort of like old people. As long as we don't push too hard we will last a long time.
