Reduced power to headlights

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=42269
Printed Date: July 06, 2025 at 8:24 AM

Topic: Reduced power to headlights

Posted By: tmpintnl
Subject: Reduced power to headlights
Date Posted: November 04, 2004 at 10:42 PM

Hello - I am considering installing a daytime running light module in my car. This module provides 30% power to the headlights when the key is on. My question is: Does operating automotive headlights at reduced power harm the lights in any way? I have halogen sealed beams, and intend to operate the high beams in this way, and wire it so that the module deactivates with the headlights turned on. I don't want to do this installation if it will cause stress to the light filaments, or cause stress to the wiring in the car. Thank you for any input.

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Toby Peterson

Replies:

Posted By: wolf.zero
Date Posted: November 07, 2004 at 4:55 PM

the day running light module dims the lights by restricting the amount of current to the filaments so there is less "stress " on the filaments, but as you will be running the lights for a longer period of time you will be increasing the use of the lights so they might wear out quicker than if you just used them as and when neccessary.

simple solution would be to fit a relay to switch on the side lights when the key is on (side light bulbs are cheaper than sealed beam units) you may need to fit a couple of diodes to stop the rear lights coming on but probably still easier than the day light module

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