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Re: [EVDL] LED Taillights - a money saver in gas cars? -rangeextenderin EV's? - an an

A 3W red Luxeon sounds excessive for a taillight.

Lumens are different in 2 ways. First off a white taillight bulb may
produce 400 lumens of white, but the red filter only makes the light red
by blocking more than 2/3rds of the light energy because the blue and
green components are useless (a filter does not change photons of one
wavelength into another).

Then the bulb throws those remaining lumens at 360 deg. Half will
strike the back, which may be silvered so at least some of it will end
up getting thrown forward again.

It is possible for an LED to be excessively bright only in the center.
Even in "wide" spread LEDs, like 130 deg, the intensity is greater
straight ahead, decreasing substantially as angle increases. This can
result in a very bright spot projected onto the middle of a taillight lens.

Multiple 7.6mm P4 pkg are a really good option. They get used a lot in
commercial taillights. Since the pkgs can be spread out, they won't
make a single bright spot. There's also far less thermal issues when
it's done this way.

Danny

David Nelson wrote:

>I have actually tried one of those in my Gizmo. Since it only has one
>tail light I'm concerned about visibility. It is very bright and is
>definitely visible from the sides. I initially used it as my tail
>light but it overpowered my brake light. I finally just purchased a
>wide array led light for my brake light (it has leds pointing directly
>to the sides to light up the reflector) so it could be seen over the
>3W running light.
>
>Keep in mind that the lumens from an led is measured differently than
>from an incandescent bulb. I don't remember exactly what the
>difference was but the superbrightleds.com site talks about it.
>
>David
>
>On 9/25/07, Paul <[email protected]> wrote:
>
>I don't know of any LED replacement bulbs with DOT approval but I
>have one in mind to try:
><http://www.superbrightleds.com/specs/115x-xLX3.htm> Its not cheap,
>but it has a wide beam angle (130 degrees) and 240 lumens of output,
>about 60% of the brake light on an 1157 car tail light bulb (one
>candlepower equals 12.57 lumens.)
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>

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