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min. amp rating for headlight upgrade?

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=31726
Printed Date: August 25, 2025 at 10:39 AM


Topic: min. amp rating for headlight upgrade?

Posted By: equium
Subject: min. amp rating for headlight upgrade?
Date Posted: May 06, 2004 at 5:14 PM

hi, i will be using relays to bypass the stock wires to my headlights and use larger gauge wires for increased brightness.  what is the minimum amp rating i should get on the relays?  this is going in a '91 F250 diesel with dual batteries.

thanks




Replies:

Posted By: Teken
Date Posted: May 09, 2004 at 9:24 PM
Technically speaking you should know the head lights power rating to be sure what current is being consumed through the wires in the circuit.

Regardless of that fact, assuming the head lights are not HID assemblies, and simple halogen bulbs which they are.

The output power would be no more than 65 watts, and the working voltage is 12 volts. The current rating would be 5.42 amps per bulb X 2 = 10.84 amps.

So you could use a simple 20 amp relay. I would however recommend the 30/40 amp relay to insure longer service life, due to contact arching.


Regards

EVIL Teken . . .




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