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

Simple: start with a red Luxeon LED.
I think they come with different opening angles (lenses).

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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Danny Miller
Sent: Tuesday, September 25, 2007 8:18 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] LED Taillights - a money saver in gas cars? -rangeextenderin EV's? - an analysis

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.


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 site talks about it.
>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:
><> 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

For subscription options, see

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