As many will know, the light output of a headlight goes up sharply as the feed voltage increases in the range 12-14 volts. Considering that even in a new car that there is always some voltage lost between the battery and the bulb, I was wondering what it might be in an older car, as it probably gets worse with age of the car. I did an experiment over the weekend measuring the volts drop in my old Rover 600 (because a gorilla can access the headlights on that car, unlike the Gen7!). I was quite surprised to find there was (near as dammit) 1V being lost.
Does anyone have any feel for how typical this may be?
I've heard stories in the past about people wiring in new supply circuits to their headlights, using the shortest possible runs of comfortably rated cable, operating from a separate relay. Could be worth doing, as opposed to buying the brightest, and most short-lived bulbs?