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Discussion Starter · #1 ·
I have replaced my Dome, Map and cargo lights with LED replacements.

For anyone else who has installed LED's before; did you notice that at night, the LED's were still just barely lit despite not being turned on?

If I turn them off by the hard switch on the map lights and dome light, they do turn off completely. However, any other time when they should be off, they are still barely lit. It is fairly obvious at night.

They do this even when the car is turned all the way off and the key removed for a while.

I'm wondering if anyone else has noticed this? Maybe it is just stray voltage in the circuit. I don't know for sure though.
 

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Oh yeah, this has been discussed in great detail with an LED expert and was left scratching his head :D


http://www.nissancubelife.com/forum/index.php?topic=782.0

I have house LED light bulbs you can remove from the fixture and lay one on a table for hours and they glow with zero power available.

Some of what you are experiencing is bleed across the switch, being you can kill it. The ones in my cube go dead right away but not every car is the same.

My home bulbs will glow 10 hours straight.
 

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No offense intended, but LED's will not glow if no voltage is applied (they are semiconductor devices and if no power is expended, then no power will be released). Any explanation for what you are seeing?

PS. Such "glow" behavior is suggestive of the chemical "glow" of some remote control buttons that maintain declining light output after the light source is extinguished. LEDs themselves do not do this.
 

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Discussion Starter · #4 ·
Wow ChristineK, thanks for linking me to that thread. It made for a good read.

This has to be stray/leaking volts/current I'm seeing in these LED's.

I noticed one thing for sure, is that the lights are controlled via the ECU or some sort of timer module that keeps them on for a certain time after I get out of the car. This has to be where the stray volts are coming from.

I'm not going to worry about it at all, those stray volts were there when the OEM incandescent bulbs were in there too. Now they just won't drain the battery as quickly. :D

Oh yeah, did you notice at Autozone, that they have the larger panel of LED's with the Festoon adapter for $17.99? That one will fit in the dome light, that is what I used. I used the smaller one that was $14.99 in my rear cargo light and it works great in there.
 

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TrevorS said:
No offense intended, but LED's will not glow if no voltage is applied (they are semiconductor devices and if no power is expended, then no power will be released). Any explanation for what you are seeing?

PS. Such "glow" behavior is suggestive of the chemical "glow" of some remote control "buttons" that maintain declining light output after the light "source" is extinguished. LEDs themselves do not do this.
Hey see that link above and search for the pic's I took over 8 hours after the bulb was removed from the fixture and layed on the table OVERNIGHT. :eek:
 

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I someone with these LEDs is in the D.C./Baltimore area, let me know and we can figure out the cause in under 10 minutes (over a beer). I'll even provide the beer.
 

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ChristineK said:
TrevorS said:
No offense intended, but LED's will not glow if no voltage is applied (they are semiconductor devices and if no power is expended, then no power will be released). Any explanation for what you are seeing?

PS. Such "glow" behavior is suggestive of the chemical "glow" of some remote control buttons that maintain declining light output after the light source is extinguished. LEDs themselves do not do this.
Hey see that link above and search for the pic's I took over 8 hours after the bulb was removed from the fixture and layed on the table OVERNIGHT. :eek:
Took a look at the thread and I'd agree with it being something peculiar with that white dopant. I've never seen a red or blue LED glow on for even an instant with power removed (and normal semiconductor field behavior can't explain continued photon emission), so it would have to be chemical (phosphorescence, radioactivity, whatever).

Hi-TecDesigns said:
The afterglow has really been bugging me (thanks, Christine! :no:), and the scientist in me won't let it go, so I've been doing some digging. WARNING: the following is going to get technical and may annoy the bejeesus out of some... you've been warned, so if someone's brain turns to mush and dribbles out of their head after reading this post, you have no one to blame but yourself (and possibly genetics).

A common method of making white LEDs is to use cerium-doped yttrium aluminum garnet (Ce3+:YAG), which in and of itself is not remarkable in any major form. In fact, during normal operation, those LEDs light up through scintillation, not phosphorescence (which is what we need here for an afterglow to take place once power is removed, barring no radiative substances in the mix). However, the cerium oxide used can often be contaminated with thorium... another mildly radioactive rare-earth substance (it's not harmful to the process a a whole, so there's little need/desire to try and filter it out). This brings us full circle to an LED that can continue to glow without power, and even through its typical mode of scintillation, because of the radiative impurities.

Now, I'm not saying this is what's actually happening (I still want one of these guys in my hands to experiment for myself and I'd have to dig up the Geiger counter), I only offer it as a possibility.
 
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