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does anybody use these and if so how many leds per bulb. also would a 15 leds 1156 be not as bright as 24 leds on a 1156?

for what?

1156 is the bulb i wanted to replace my taillights with them

can u see the leds thru the tailight? i dont get it

He's talking about things like these:

http://www.foximas.com/discount/redytypeyledybulbs.htm

91scoobiesubie, I have to advise you to avoid these units.

When done right, LED signalling can be quite good. LEDs respond almost instantaneously to current, so they light up faster than incandescent bulbs. LEDs almost never wear out, so they don't require replacement. LEDs are more efficient than incandescent bulbs, so they use less power.

The problem is, it's hard to do it right. The first issue is light color. Normal LEDs produce light at one fixed wavelength and don't actually fulfill the requirements of automotive lights because partially color-blind people can't tell what color they're supposed to be.

The second issue is light distribution. Incandescent bulbs have filaments that occupy a very small volume and emit light more or less evenly in all directions. The reflectors and lenses in our cars' taillights and turn signals are designed to capture that light and reflect it in a controlled way, giving high intensity directly behind the car while still giving good intensity from all other directions. The cluster of off-the-shelf LEDs on these "bulb replacements" produces light in a completely different pattern; most of the light comes out of the LEDs in a 45-degree spread or so. Each of these spreads has a different origin. Basically, it completely screws up the optics that Fuji Heavy Industries spent so much effort engineering.

The third issue is current draw. On our cars, the turn signal control unit uses a bimetal strip to control the flashing. It's a strip of two different metals attached together, so when it heats up it curves to the side. Current is carried through the strip to the turn signals. So, it heats up and curves to break the circuit, then cools down and moves back in to close the circuit again, and the cycle continues. To some degree, then, the period of the flashing is determined by the current drawn (since that controls the amount of heat generated). If you replace the bulbs with LEDs that draw much less current, the lights will blink much faster than they are meant to.

If you want brighter taillights, I would suggest getting some better incandescent bulbs. For the single-filament bulbs, a 3497, 2396, or 7506 bulb will be noticeably brighter than stock. For the dual-filament bulbs, try a 3496, 2357, 2397, 7528, or 7225 bulb. A W5W can replace the wedge-base bulbs. These will safely work very well.

thanks for all the info and heads up you really know your sh@%

Thanks. :) I learned to drive on my old Euro-spec Mercedes 300D. After a wreck, the body shop replaced the front lights with US-spec ones and I was shocked how terrible the lighting was. Like most people, I had just figured "lights are lights," until the potential differences in lighting became so obvious. So I made an effort to learn about automotive lighting and since then have been on a mission to teach others. :)

vrg3, I can't agree with you more on lighting, the Europeans know what they are doing. After replacing a few bulbs in my Mercedes with non-european wattage bulbs, I noticed a difference, so I took the time to find the correct bulbs, and things were alot better. On the Subaru, I am making sure to use only the european bulbs, to make sure I get the highest quality of lighting, and not melt the plastic...

I heard somewhere that Euro lights are better because they don't need to illuminate signs like US lights do. Signs there are lit, so that leaves manufacturers free to drop the light pattern and since that reflects in other drivers' faces much less, they can also up the lumen output. I guess that leaves them performing more like driving lights. I think I got that from an old design magazine. I'll see if I can dig it up if I'm not too lazy.

Steve

Steve, that's a common misconception. It's propagated by NHTSA, who uses it to justify the high-glare headlamps in the US.... but it's just not true.

Next time you're in Europe look at the traffic signs. There are plenty of road signs that are unlit, both on the side of the road and overhead. European headlamps work just fine to illuminate them. It doesn't take very much light to illuminate a sign, and enough of the headlamps' light bounces off the road and other objects to light them all up.

European low beam patterns are more like fog lights than driving lights, though of course much higher. They provide a relatively even distribution of light below the horizontal centerline, and a little bit above the centerline on the curb side of the road, to help illuminate stuff at the edge of the road.

European high beams are more like driving lights; they're really bright and shine all over the place. They're better than US high beams.

The "harmonized" lights like those on 92-94 BC/BFs are kind of funny; their low beams are on the high side of ECE's permissible glare, and their high beams are on the low side of ECE's required output.

That's interesting. I did notice a lot of unlit signs, but they were in otherwise well lit areas, and anyway, I didn't spend too much time thinking about automotive lighting with all the honeys around (not in Egypt, though, but then, they don't use headlights most of the time ). So is it just because the US makers lobbied to allow cheaper lamps? It would seem to me that it would be beneficial at this point to have the same regulations in as many markets as possible, and the Euro lights could be sold to insurance companies as a safety improvement. I'm sure it would be more a benefit than the dubious DRLs they adopted to avoid having to sell two seperate systems in the US and Canada. I suppose we should at least adopt the metric system first.

Steve

Part of it was that long ago, US federal regulations were implemented that required standard-format sealed beam headlamps on all vehicles. The requirements were very strict and rigid, to the point that it stifled any R&D work on headlamps. In Europe, headlamp technology continued to evolve while it stayed stagnant here.

While in recent years it's become legal to have somewhat better lighting, the minimum DOT lighting requirements actually aren't too different from what they were 50 years ago.

Yes, American car manufacturers lobby heavily to maintain the lighting standards where they are, because it's way cheaper to make crappy lights than good ones. Because of the size of the North American market, it's cheaper to make bad lights here and good lights elsewhere than to just make one standard type of light.

They've been fighting this fight so much that they've actually funded supposed studies to show how the American standards are better than the European ones... this is where the claim of "European signs are all self-lit" comes from. Another claim is that "We don't need side-visible turn signals. Europeans need them because they have lots of people on bikes who have to watch out for them." I don't think I even need to explain the stupidity there...

If we could get insurance companies to lobby for better lighting that might be good... ECE lighting standards would be a huge improvement in safety on our roads.

The National Highway Traffic "Safety" Administration has nothing to do with safety. It's all about being a federal body that automakers can control. If GM gets NHTSA to approve their idiotic (no better word for it) high-beam DRLs, then they are absolved of any liability due to their dangerousness. All they have to do is say, "They conform to federal specs."

Sigh.