OT LED Trailer Lights 1157 Equivalent - Use Red or White?

[DerbyDad03]

Background:

I have a trailer that uses 1157 bulbs for the tail/signal/brake lights. Each side uses one fixture with one dual filament bulb for all 3 functions. The fixture has a red lens as a cover.

Project:

I wanted to see if an 1157 LED equivalent would make the lights brighter. 1157 LED's come in either red or white, so I bought white since I already have a red lens. After I installed the bulbs I didn't see a significant increase in output, at least not in daylight, which is when I want the brightest light. I haven't compared the difference at night yet, but nighttime visibility has not been an issue. It's mainly when the sun shines on the rear of the trailer that the taillights are not that bright. They are bright enough to pass inspection, but even the inspector's have mentioned the lack of brightness.

That leads me to 2 questions:

Specific to my requirements, would red LED's behind a red lens be brighter?

If not, what is the purpose of red 1157 LED's? Places that sell them say that they are used for tail lights, but they don't say anything about the color of the lens they should be used with. I've never seen clear lenses for tail or brake lights, but maybe they exist? Maybe that explains the need for red 1157 LED's?

[Meanie]

Yes

You use the color LED equal to the color of the lens.

[DerbyDad03]

Not questioning your answer, just curious as to why? How does a red LED behind a red lens look brighter than a white LED?

[dansabrservices]

While I don't have specific numbers, think of the difference this way:

White light consists of light of all colors together. This means that the energy converted to light is spread across all colors. With a RED lamp, al l energy is in RED only. It stands to reason that the red would produce a brighter light. Also, in the case of the white bulb, the "extra" light (co lors other than red are absorbed by the red cover only allowing a subset of produced light outside of the lens cover.

Make sense?

Dan

[DerbyDad03]

On Monday, February 27, 2017 at 7:21:28 PM UTC-5, [e-mail] wrot e:

e energy converted to light is spread across all colors. With a RED lamp, all energy is in RED only. It stands to reason that the red would produce a brighter light. Also, in the case of the white bulb, the "extra" light ( colors other than red are absorbed by the red cover only allowing a subset of produced light outside of the lens cover.

All those years of clear (white) 1157?s behind red lenses on millio ns of vehicles.

Why didn't they color them red? Not bright enough to shine through the colo ring?

[Pat]

You missed his point. With old 1157's (ie, incandescent), the light is always white. You can filter it to red via a coating on the bulb or via a red cover or both. LEDs are different. They produce one single color. If that color is red, there isn't much difference between using a red cover or a clear cover. White LEDs, however, are really blue. A coating of phosphor glows white when struck by the blue light. So, as he said, the power coming out of the LED is spread across the spectrum in order to look white. If you then place that LED behind a red cover, all the colors besides red get absorbed and turned into heat. If the LED is red to start with, there are no other colors to get absorbed. Bottom line: With LEDs, using a red led means all the produced light makes it out but using a white led wastes some. With old incandescents, it makes very little difference.

[DerbyDad03]

rote:

the energy converted to light is spread across all colors. With a RED lam p, all energy is in RED only. It stands to reason that the red would produ ce a brighter light. Also, in the case of the white bulb, the "extra" ligh t (colors other than red are absorbed by the red cover only allowing a subs et of produced light outside of the lens cover.

OK. Thanks. I'll try the red 1157?s and see what happens.

[mkolber1]

Let us know what you find

[DerbyDad03]

I'll know on Friday. I ordered these taillight bulbs...

...and these side marker bulbs:

[Meanie]

I can tell you.....the red LEDs with red lens are brighter than the white LEDs and different color lens. Been there done that. I also once believed the white would be brighter and ordered all whites for my turn signals and brake/running lights. After install of one side, leaving the other side with the stock incandescent and not noticing a significant difference, I spoke with retail reps and friends who are electronic wizards. Lucky for me, the etailer I purchased from let me swap the whites for the proper red and amber colors I needed. Again the same comparison method and they appeared much brighter.

[gregz]

Just dimmer. All those are really orangish. Red led is real red.

Greg

[DerbyDad03]

The LED's arrived last night, sort of.

The Red 1157 tail lights work great. Much brighter than both the incandescents and the white LED's.

The side markers, both in amber and red, are also brighter than the incandescents but they screwed up the order. I needed 2 packages of the red T10 bulbs (4 bulbs total). They sent me 1 package of T10's and 1 package of T25's - huge compared to the T10's. The bar code label matched the T10, so I can't blame the picker, (s)he just picked what the scanner told her to.

[DerbyDad03]

The side markers are even brighter now. I was having trouble with one socket. I had to position the LED in an exact spot to have it work consistently.

For $3.39 x 4 I replaced the side marker fixtures. The new lenses and nice clean sockets really made a difference. The side markers are bright enough to be bright even in the sun light.