Custom LED Underbody lights

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=77764
Printed Date: April 28, 2024 at 12:51 AM

Topic: Custom LED Underbody lights

Posted By: mvwiggie07
Subject: Custom LED Underbody lights
Date Posted: May 14, 2006 at 2:50 PM

I am in the process of designing and building a set of LED uderbody units for my 94 camaro. I work alot with electronics and know stereo systems pritty darn well. THe problem comes when everywhere you see that LED's are the new thing and low energy and that you can change out tail lights and gauges in a car, but what about fuses? How do i know what fuse size to run per LED and set on the same switch? is there a formula or basic number out there?

Replies:

Posted By: firstrax
Date Posted: May 14, 2006 at 3:32 PM

More info.

What LEDs, how many, series, parallel, ect.

Posted By: KarTuneMan
Date Posted: May 15, 2006 at 1:06 AM

Ill bet you can buy'em cheaper than you can make'em....

www.visioninet.com

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Posted By: KarTuneMan
Date Posted: May 15, 2006 at 1:09 AM

https://www.visioninet.com/product/led/undercar_kits/index.html

woops sorry

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Posted By: stealthone
Date Posted: May 24, 2006 at 9:20 PM

mvwiggie07 wrote:

I am in the process of designing and building a set of LED uderbody units for my 94 camaro. I work alot with electronics and know stereo systems pritty darn well. THe problem comes when everywhere you see that LED's are the new thing and low energy and that you can change out tail lights and gauges in a car, but what about fuses? How do i know what fuse size to run per LED and set on the same switch? is there a formula or basic number out there?

The average LED current flow is 20 ma. You basically fuse the wire as you couldn't fuse small enough to protect the LED's.

One thing to remember is that LED's are subject to inrush current damage. You should put a small resistor in front of each series chain of LED's to limit inrush current.

Posted By: ff-mike
Date Posted: May 25, 2006 at 10:55 AM

stealthone wrote:

The average LED current flow is 20 ma. You basically fuse the wire as you couldn't fuse small enough to protect the LED's.

One thing to remember is that LED's are subject to inrush current damage. You should put a small resistor in front of each series chain of LED's to limit inrush current.

All electronics are subject to inrush current, but that is not the reason that you use resistors on LEDs!

LEDs are current operated, not voltage operated. The reason you use the resistor is to limit the current, otherwise it goes pop.

To find the resistor needed, you need to subtract the voltage drop across the LED from the source voltage, and divide that by the current rating.

A typical 3V 30ma LED would be like this off of the car:
resistor = voltage(source-rating)/current
resistor = (12-3)/.03
resistor = 9/.03
resistor = 300 ohms

NOTE: all LEDs have different ratings, and some may already have resistors included in the packaging (eg replacements for taillamps)