Headlights and Relays

[DesertCat]

Originally Posted by BMERDOC

So I was looking over my truck for upgrades. Anything I can knock out quick and cheap. I looked into doing the headlamp relay upgrade to my truck so I measured voltage at the plug and found it to be .5v lower than system voltage. So am I correct to assume that its not a matter of voltage but its amperage where it counts?

Well, they are relative to each other, but yes assuming you can get full voltage to the lamps... current is the problem to be solved.

The fact that your voltage is low at the lamps means the path's resistance is too high (current is restricted and volts drop - Ohm's Law). This can be wire size, connector integrity, switch contacts and/or grounding. The voltage you read is the sum total of all this.

Others have chimed in here with suggestions of how... just thought I would answer the "why".