LED Wiring, Is this correct?

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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=61435
Printed Date: May 08, 2025 at 6:11 PM

Topic: LED Wiring, Is this correct?

Posted By: skeeler
Subject: LED Wiring, Is this correct?
Date Posted: August 16, 2005 at 1:03 PM

Hello all. Sorry for the request for proof reading, but I just wanted to make sure I had the wiring correct before I go to the install phase. I am doing adding some LEDs to the interior of my boat. All the LEDs are 2.5volt, add the current provided will be 12volt. Is the wiring digram I made below correct?

Replies:

Posted By: ff-mike
Date Posted: August 17, 2005 at 5:21 PM

What is the current rating of the LEDs? Both need to be considered when designing the ckt. What you have there is good for ~ 17mA

Posted By: skeeler
Date Posted: August 18, 2005 at 8:57 AM

ff-mike wrote:

What is the current rating of the LEDs? Both need to be considered when designing the ckt. What you have there is good for ~ 17mA

These are the LEDS I went with; https://www.lsdiodes.com/shop/index.php?main_page=product_info&cPath=1&products_id=17

Posted By: ff-mike
Date Posted: August 18, 2005 at 9:26 AM

OK, I looked at the specs for the LEDs chosen
Forward Voltage: 2.1-2.4
Forward Current:: 30mA

We will also assume 13.2V for the battery on the boat when it is running

Worst case scenario
All the diodes are 2.1V. This nets us 8.2V for them, and 5.0V to be dissipated by the resistor(s)
5.0v/30mA = 167Ohms
Not a very common size. But 2 330ohms in parallel would be 165. Good enough for us

Opposite side
Diodes 2.4V, net 9.6. Boat off & battery gives us 12V. 2.4V to be dissipated
2.4V/30mA= 80 Ohm
Again, not very common. a 100 ohm would give you 24mA
The 165 ohms (2x330 in parallel) would give you ~ 15mA. Plenty to light them up