Why does this not suprise me with the ever increasing brightness of car lights over the past few years, if the headlights don’t blind you the brakelights will!

21Watt bulb power vs 0.9 watt LED?
21 * 3% eff = 0.6 watt worth of photons vs 0.27 watt worth of photons

Gotta love bright idea’s

(Assuming 3% efficiency for bulbs, and 30% efficiency for LED’s)

@steven: photons aren’t measured in watts (well, actual photons are a different matter altogether). It has nothing to do with wattage, rather light intensity, ie lumens (or milli-candelas in the case of LED’s)

Also, no bulb to replace. Unless something goes catastrophically wrong, you’ll likely replace the car before you do the leds.

also most cars that come with LED lighting from the factory use larger, brighter and I’m assuming more reliable LEDs (read: more resilient against vibrations, extreme temps, etc.) Any idea what the OEMs use and where I could get something similar?

I did this for a school electric car project in college. It had round brake lights, so I mounted high-intensity LEDs to a round PCB, busted the base off of a standard bulb, soldered the wires on, and epoxied it together. Drop-in replacement.

Oh, and P.S. about the photon energy, all that white light is filtered down to only red. That’s right, OYGBIV is all wasted, as well as a lot of IR. The LED releases light only in the part of the spectrum you need a brake light to do so: red. So, it’s brighter, even though it’s not releasing as much actual light energy. More light makes it to your eyes.

looks like crap to me!

Next time, consider the red-orange snapled from Lumileds!:
http://projects.dimension-x.net/archives/219

As geep says –

using 1 resistor at 330 ohms per led is rediculous.

That light could easily run 5 or 6, 2 volt leds in series with one small resistor, or better, an led driver.
Efficiency in that system is CRAP, as its burning off 10 of the 12 volts. BS ‘efficient’.

frollard, that is correct. he should at least put three LEDs per series so that it is more efficient. in that case when one led dies, the rest 6 should work great.

As their all pointing straight-backwards and there appears to be no kind of lens in front of them if you are looking at the car at an angle you couldn’t see if the light was on or off.

good thing that they are only for the people driving directly behind you

There’s a basic misunderstanding here. The original lamp was at the focus of a *fresnel lens* (see Wiki) which redirected the divergent light towards the rear. A Fresnel lens is simply a compacted form of a conventional lens and produces the same result – it is beam-forming, *not* a disperser. So the original arrangement wasn’t designed to disperse the light to the sides.

With the change over to /LEDs\ (which contain their own lens) there is no longer a single source, so the fresnel lens has no use, but even if all the /LEDS\ were aligned to face backwards they still have a considerable beam width, likely to be greater than the original beam.

But they don’t have to be all aligned rearward – they can be splayed so they actually give a wider overall beam, and who is more interested in you stomping on the brakes – the driver directly behind, or someone entering from a side road?

After just completing a 5kkm road trip I found that the new /LED\ stop, tail and turn lights are not only brighter, they have greater dispersion than the old style.

It’s true that connecting the /LEDS\ in series groups with single resistor is more efficient, but it also makes them more sensitive to voltage variations. Since hackers aren’t worried about production expenses here is a constant current supply designed to overcome this problem in solar-powered houselighting;

http://www.ozvalveamps.elands.com/techsite/ledlight/ledlight.htm

@twistedsymphony:
Lets look at a standard Red LED with a voltage drop of 1.6 volts. When it is running near its maximum light output, it can get warm. Add environmental factors, and your LED’s can get over 85 degree C fairly easily. This causes your 1.6 volt LED to become a 1.3 volt LED. If you had 5 in series, your 8 volt drop becomes 6.5 volts and now your resistor is too small and your LED’s die. This is why larger LED systems should use a LED driver (aka constant current driver) instead of a voltage regulator.

It’s great and all, except automotive power isn’t guaranteed to be 11.5-14.6VDC. It can spike to 40VDC, which will pop these LEDs, due to having current limiting resistors instead of a constant current source regulator. For the hobbyist, no big deal, but it is something someone should consider.