If this question needs to be moved or removed I'll understand.

I have relocated my motorcycle license plate and the stock plate light assembly will not fit. So I thought of lighting the plate with superbright LED's. Looking through Newark's catalog (Mouser and Digikey didn't have the right voltages or sizes) I found a LED that is rated for 12VDC (part # 35C0866). However, the current is listed as "DC Iopr 20mA." Now the stock light bulb was 8W. So I figure the current to the bulb was approx. .67A. Is this way too high? Will I destroy the LED's if I try this? Also I planned on connecting three LED's in parallell to the stock wiring. Since I have forgotten all my formulas, I cannot figure out how this would affect the lights. The LED's also come in 24VDC/20mA configurations. Would this be any better? Any help would be appreciated. Thanks.

I'll try to help.

Most LEDs are ~2V I think, so a 12V or 24V LED is probably a circuit with a ~2V LED in series with a resistor.

If the bulb voltage is 12V, then a 12V LED is fine. You could also use other LEDs and adjust the current with a resistor (or use six 2V LEDs in series for 12V).

I've just read theory about LEDs while reading about electronics in general, so if somebody could confirm this, that would be nice.

Jupiter, your guess is probably right: if an LED is described as having a common forward voltage rating of 5, 12 or 24V, it's probably got an internal resistor, and the rating is just telling you that you get the rated current (and thus brightness) at that voltage level. They're tuned for common supply voltages for obvious reasons.

This LED you're talking about, finleyville....I guess it would work, but it seems a little overengineered for the purpose. I'm also not wild about the smoked lens -- isn't that opposed to your purpose here?

Instead, consider getting several plain 5mm LEDs from White Light LED. He's a small one-man operation. I recommend the 1500mcd 5mm 50 degree dispersion one. You can put three of those in series with a 12V supply. Put a single resistor inline to keep current under control, and you'll end up with a 4500 mcd light with no funky lens for about half the cost. If you want potting, you can dip the finished product in epoxy after it's tested and working. For more light, put several of these series sets in parallel. I don't know if you can get away with a single current limiting resistor for all sets or if it's better to use a separate resistor on each set.

It seems to me that you could put 9 to 21 LEDs in a concentric pattern and get a very nice display.

In addition to white LEDs, you should also consider the large red superbright LEDs you can find everywhere. Each one can handle 50mA, which is more suited to this kind of setup, and they're physically larger, so they naturally spread their light around over a wide area.

You might also think about splaying the LEDs a bit so they point in different directions, giving a wider dispersion pattern than that of any one LED. You don't want to go with a diffused LED to get wide dispersion, as that cuts down on brightness severely. Simply splaying the LEDs is probably a better plan.

And that brings me to safety: there are probably laws you're breaking by designing your own tail lights. Surely the department of transportation has regulations regarding this kind of thing. If you're going to do it yourself, you at least need to make a convincing effort at addressing safety issues like the visibility ones I mentioned.