homemade DRL question

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=27730
Printed Date: August 06, 2025 at 5:39 AM

Topic: homemade DRL question

Posted By: southpawboston
Subject: homemade DRL question
Date Posted: March 04, 2004 at 3:16 PM

hi all, kind of a noob question:

i'd like to make a homemade DRL circuit for my '02 hyundai elantra (does not have factory DRL). i designed a single-relay setup that i've tested and which works nicely to switch between normal headlight mode and DRL mode (DRL "on" when parking lights are "off" and ignition is "on", otherwise normal operation). but now the only thing i need is an appropriate resistor to drop the voltage to the low beams when the DRLs are on. i'd like the low beams (2 standard 55W bulbs) to run at about 50% normal intensity. what's a good resistor value? what about the wattage handling? i'm not well versed in resistors. my rough guesstimation is something like 0.5-1.0 ohm and 100W?

thanks for you help!

Replies:

Posted By: cbag1
Date Posted: March 15, 2004 at 3:02 PM

Wirewound resistor would likely work in your project. 2 ohms in 50 watts. Also, a big current flows to the resistor. It is about 4 amperes with 2 electric bulbs of 60W when it dim. Then the electric power of about 32W consumes with the resistor.

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Posted By: cbag1
Date Posted: March 15, 2004 at 3:11 PM

note:

A wirewound resistor is made of metal resistance wire, and because of this, they can be manufactured to precise values. Also, high-wattage resistors can be made by using a thick wire material. Wirewound resistors cannot be used for high-frequency circuits. Coils are used in high frequency circuits. Since a wirewound resistor is a wire wrapped around an insulator, it is also a coil, in a manner of speaking. Using one could change the behavior of the circuit. Still another type of resistor is the Ceramic resistor. These are wirewound resistors in a ceramic case, strengthened with a special cement. They have very high power ratings, from 1 or 2 watts to dozens of watts. These resistors can become extremely hot when used for high power applications, and this must be taken into account when designing the circuit. These devices can easily get hot enough to burn you if you touch one.

Posted By: southpawboston
Date Posted: March 15, 2004 at 4:23 PM

thank you so much, cbag1!

i will look into to wirewound resistors