As I was brousing though the superbrightled.com catalog yestrday I found a note that said (in some sort of wording) "do not use clear LEDs for red lenses, use red LEDs for red lenses." Does anyone know why they would say this? Why wouldn't clear (white?) LEDs work behind red lenses? I am cocnerned that red LEDs behind red plastic lenses will not be as bright as the clear/white LEDs. Any ideas out there?

 

I believe it's because of the narrow band of light frequency that an LED produces. "White" LED is usually not the same as your garden variety automotive light bulbs. The white LED produces very narrow band of light frequency while your tungsten-filament light bulb produces all kinds of light frequencies that look "white" to your eyes.

Red lense is like a filter. It allows light with "red" frequency to pass through, so the human eyes perceive the light as red. Now if you put "white" LED, most of the light produced will not be passed through the red lense because it gets filtered out.

I know I should be able to word that better, but hopefully you catch my point.

 

Off the shelf LED tail light bulbs don't work on our cars. I tried them and they fried my turn signal switch. They required a load equalizers that got so hot, it melted the zip strip I had it loosley mounted with. I'm happy I did not start my car on fire. If you want LEDs, you should buy a designed product like Ecklers sells.

 

I checked the Ecklers page and the red LED tail light bulb they used to have is discontinued (maybe for the same reason you mentioned). All they have now is $499 tail light kit (which is obviously overpriced). I am sure there is a better alternative than spending that kind of money for simple LED lamps. When I find them (or design such a system if found to be nonexistant) I'll post it. I am not sure I understand what you mean by a "load equalizer" but if they draw too much current they could easily be switched with a relay (or SS relay - which may be what you had).

 

Ah! I think I figured out what you menat by a "load equalizer." Apparently the LEDs draw so little current that the can't trigger the flasher (old flash units worked on bimetal thermal switches so that current caused them to open and cycle). The only way to force these older system to work properly was to add a resistor that drew more of the bulb current and increase overall current draw. This is probably what you say heated up in your case. I'm not sure that the modern circuits use therma flashers (I'll check on that), but if they do, the same problem wold exist. If they don't (i.e. if they use modern electronic timer circuits), it shouldn't be a problem.

 

White leds have a blue peak in their output which would be filtered out by the red lenses so the total light energy delivered past the lenses would be less than using red leds. Inside the emergency flasher switch is a surface mount circuit with relay that controls the flash rate for both signal and 4-way modes. The flash rate is load sensitive to alert the driver of a burned out bulb. By adding resistance in parallel with the leds the circuit is fooled and the flash rate remains the same. The switch can be taken apart and either the circuit modified or a new external circuit added with three wires so that the flash rate is not load sensitive and adjustable without adding load resistors. I have taken apart the switch and added an external circuit but for different reasons. An external 555 timer chip with relay would allow flash control without needing the power robbing resistors; in the process of adding this new circuit the old components are removed.

 

I've been using the LEDtronics 3157 brake light replacements for about a year and a half. On their high setting they're VERY bright. On their low setting, they emit a kind of dark ruby red light through the lenses, and don't evenly illuminate the reflector as well as the incandescents, so they look a bit like point sources through the lens. Not bad, but not perfect. Also, yes, they do cause the signals to blink crazy-quick. It's a little annoying, but not so much that I'm motivated to dig out the flasher anytime soon.

 

Hi, I ran in to this problem with LED's on my bike before. I simple way to fix this is to buy a self powered trailer light converter. I believe an example would be Hoppy Litemate #43355. Not exactly cheap, but regularly available at any auto parts store. Feed your factory taillight wiring to the converter input and the output goes to your LED's. The converter has its own power feed for the LED's. So it is pretty much a relay in theory. Mark

 

I bought a set of these:
http://superbrightleds.com/1157.htm
in the 3157 with 20 LEDs flavor.

1. They are bright when I played with them in the lab.

2. When installed in a C5 there is a problem. The socket is offset and is intended to center a 3157 filament in the center of the reflector. When the very directional light from the LEDs is installed, the light does not fill lens.

Partly because it is pointed off center and partly because the beam width is too narrow. The LED array is too close to the lens. I may remove the plastic housing from the led array and see if I can get a better "fill" of the lens.

3. LED efficiency is changing VERY rapidly. I wouldn't buy anything designed more than a year ago.

4. I don't think there is any difference in the led whether molded in red or clear plastic. This is based on real lab tests, not just eyeball.

5. WHITE leds that emit a sorta white light have a very narrow emission in the red band produced directly by the die. They also have a very broad blue component which is generated by a phosphor, excited by the the red led die. Our eyes integrate the colors and it appears "kinda white". A "die" is the small chip inside the led package.

Comparing a RED and a WHITE led of equal optical power behind a red lens, the RED led would be brighter because the red lens filters out all except the red light. The same is true of an white incandescent lamp which really has all the colors, only the red component gets through the filter.

6. I've seriously considered building a circuit board for C5s, but it would not be a plug and play. It would be necessary to separate the red lens from the reflector which is a complete pain in the aaassss. The only other option is to slice open the reflector and drop in a pcb with the leds. That is also not too desirable. Plan C is to make an entire new assembly. Its not economically feasable at this point. A full set of 4 needs to retail for $200 tops.

Sorry if this ran on too long.

Barry

 

I'd give yourself another $50 or so. Most kits I've seen are around $500. Best,

mtv

 

Concerning the white light bulb in the tail light question; I have noticed that when dumb people put white bulbs or headlight bulbs in their taillights, it will turn the red lens pink and the light will be very light red/white shining through. I know absolutely NOTHING about electrical or lighting, but I would imagine that this has something to do with the powerful headlight bulbs. This probably has nothing to do with anything that you are asking, but might be a reason why they say dont put white bulbs behind red lenses. Im sure the red bulbs will be plenty though. Hopefully something here will help

 

Yep, the LED bulbs don't work as indicators and you have to buy the resistors at $4.95 each although I don't see how they could be fitted without making a mess.

 

I have been working on led tail lamps and have settled on 50 leds per lense that are about 2" away from the lense which means the lense housing did need to be reworked. Normal leds are not bright enough in the sun, Lumileds superflux are bright enough and cost about 40 cents each or $80 total for 200. Also if moisture gets to leds they will rust out and fail in no time.

 

This can be done much cheaper in my opinion. Having went this route in my C3, it can be somewhat cheaply achieved by using truck tail lights and a electronic flasher. I haven't had the C5 tail lights apart, but I can imagine that with some thought, some mods, it can be done for 100.00 or less. Worst case would be that you would need to find a spare set of C5 light bases to mod. With the use of the truck tailights and the electronic flasher, you will not need a external load on the circuit.

Frank

 

This can be done much cheaper in my opinion. Having went this route in my C3, it can be somewhat cheaply achieved by using truck tail lights and a electronic flasher. I haven't had the C5 tail lights apart, but I can imagine that with some thought, some mods, it can be done for 100.00 or less. Worst case would be that you would need to find a spare set of C5 light bases to mod. With the use of the truck taillights and the electronic flasher, you will not need a external load on the circuit.

Frank

 

Wrong. I bought four of the 24 LED units from Ledtronics and also bought the wiring adapter harness separately from Adjure (the makers of C5 LED light kits). I then picked up an electronic flasher from Auto Zone (part # EL12) to plug into the socket that comes on Adjure's wiring adapter harness. My blinkers all now flash at the normal rate, as the led units go through the electronic flasher and the front incandescents go throught the stock flasher. "Plug and play" as they say.
BTW, I too noticed that the lights seem to show up as "points of light" so-to-speak, and I determined that this was being caused mostly by the leds that point outward in a radial pattern. I took a little silver paint and painted a 1/4" circle on the clear plastic cover, directly over these led's (there are six of them). These little silver painted areas act as little mini-reflctors and "diffuses" their light patterns much better as they are reflected off of the inside of the factory light assembly. HTH
Robert

 

I saw this and had to respond. Only a true hardcore EE would take apart his signal flasher and mod it with a 555 timer . That gave me flashbacks to my college days!

 

When ceiling light diffuser plastic is placed directly behind the lense with the leds about 1 1/2" -2" away the result is no hot spots and a light filled lense just like a new Deville. The diffuser is cheap, less than $10 for a 2' x 4' sheet.

 

The problem here as I see it is getting that sheet of plastic through that tiiiiiiny little hole.

 

The difficulty I see is that I gave up on the idea as soon as it looked like it might be faintly difficult. They're only rear lights.