LED Problem/Question, Dome Lights

Jul 27, 2007 | 10:31 PM

g7x5

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LED Problem/Question, Dome Lights

Well last week i got leds for the interior and the rear turn, and i must say once you go led you can't go back.

well anyways, tonight i took my car out and noticed when my interior lights turn'd off, the leds in the dome, didn't they are barely on like a glow, can't see unless your real close. I'm think that there is enough current going through them to light them up.
these are the bulbs i got
http://frickinbrite.com/catalog/prod...roducts_id=135

My question will this shorten the life span given that it will always be on. Also has this happened to anyone else... and could this drain the battery, which i think is very unlikely.

Jul 28, 2007 | 04:20 AM

DrewTheSuit

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From: New Orleans, LA

next time it is dark outside and you are driving switch your domelight to the off position where it won't turn on when you open your doors...i bet the dim glow disappears completely... at least my piaas do, no idea why however

Jul 28, 2007 | 04:22 AM

Calvin

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you're fine. this happens to most, if not all, people with LEDs in their domes.

here is why:

Quote:

Originally Posted by DHCrocks

what's happening is that the dome light circuit is negatively switched. what that means is that when the door is opened or you flip the switch on, one of the leads to the light goes to ground and completes the circuit. When the light is off both leads to the light will actually be given +12 volts and since there is no potential across this there is no light. BUT since the positive voltage is actually going across different paths in the wiring there is a very small difference in resistance in the wiring, this is giving off a very small voltage differential between the two leads.

now comes the problem with the cheap festoon leds. they typically overdrive the leds which is why they always burn out so fast. I've gotten anywhere from 1 to 3 months on those things before they start to burn out. When they overdrive the leds they using a too small resistor value, and the small amount of differential voltage in the dome light circuit is enough to give off a faint amount of light. If the resistor was higher then the voltage would not be enough to overcome it and light it up.

Last edited by Calvin; Jul 28, 2007 at 04:27 AM.

Jul 28, 2007 | 06:37 AM

DHCrocks

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From: KB town - Kapiolani

BINGO...wow thanks for looking that up Hero.

Jul 31, 2007 | 12:40 AM

jig8

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So then the only question left is....

are these cheap festoon LEDs that will burn out quick?

http://frickinbrite.com/catalog/prod...roducts_id=135

they're not exactly cheap....but that's all relative i guess...

g7x5 - I have the exact same bulbs in my car, in the dome, and the door/step lights. I've also noticed the slight glow at night...so I'm wondering the same question....will these burn out quick.

I've done a fair amount of reading on in these forums, and everyone seems to be happy and suggest getting vleds, which is what I got, so hopefully someone can speak to this......that they've had the festoons in their car for years and no burn out!? maybe?