LED Headlight

[bikin' Ed]

I've been checking out lights for my bicycle ever since I started doing ultra events. Believe me, if this light is all that is advertised, it is a bargain. I'm pretty sure you'll see one of these on my bike next season. Thanks for posting the link.

[biotilldawn]

Glad to see all the ideas! Thanks.

I used Philips LumiLeds Luxeon LEDs in a couple of non-automotive applications, and am impressed with their robust design, specified outputs, and overall quality of construction.

They have a new Luxeon Rebel LED designed especially for the automotive industry, should be an interesting little unit...

I hope to reverse engineering the existing daytime-running LED headlights from a new Audi. I learned a lot about signal light design by reverse engineering turn signals from my local junkyard.

Thanks again for all the information and expertise!

[CarlosP]

Excellent thread! I was just looking up information on installing LED bulbs on a headlight to maximize battery use.

I also came across these LED bulbs designed for autos. Maybe if you tinker around with a couple of them and align them just right, you might get some decent lighting. Well, maybe at least for driving in areas were its not pitched black.

They are pretty cheap, I think they might be worth a shot:

2 X H3 Headlight Fog Light 9 SMD LED Xenon White Bulbs - eBay (item 130352670433 end time Jan-14-10 15:49:07 PST)

H11 36-LED Car Fog Headlight Light Foglight Bulb Lamp :eBay Motors (item 160373677145 end time Jan-27-10 01:54:48 PST)

[jonathan150cc]

I think you've done a very good job here.

The only thing that I would add is this. Isn't your electric bike considered a "bicycle"? If so, being DOT approved lighting isn't really an issue, right? Also, for all that work, which is awesome, don't get me wrong, you could have just added 3-4 battery powered LED bicycle lights which can really light up the road.

I used to bike commute and I had a small "array" 3 lights which totaled something like 12 LEDs and then 2 small halogen bulbs inside of those. They made by Bell and only costs $12 each.

That would be zero draw on your electric bike's system and probably light up the road more.

Just food for thought.

[wagonman76]

Originally Posted by captainslug

Typical automotive halogens output 1500 lumens per bulb at 55 watts.

1,000mcd = 1 candela = 1 lumen. So a 55,000mcd LED is only 55 lumens.

to get 1,500 lumens you will need 30 of those 55 lumen LEDs per headlight, but you will only get the same intensity level if you have optics to go with the array, or make the array so that the LEDs are focused to converge at an ideal distance. If you can find the datasheet for those LEDs it will tell you want the drop-off distance is for their output.

You may not be able to replace your automotive high beams with LEDs, but fog lamps or running lights are very possible.

I revisited this thread the other day and it got me thinking.

Pretty sure low beam is 55 watts, and high beam is 65 watts. The biggest difference is the aim. So if 55 watts is 1500 lumens, I would think 65 watts should be about 1773 lumens.

I looked up the ebay link on page 1 for the small LEDs and if this would work, it would be good deal. 5mm LEDs, 16000 mcd typical, 18000 mcd max. 100 for about $12. So at 16000 mcd, you would need 94 LEDs for low beam, 111 LEDs for high beam. Arrange them on a PC board into a 2 1/2" square or rectangle or round or whatever best matches your existing headlight, and add the appropriate resistors.

Get a cheap set of junkyard headlight bodies to play with. So you can use the headlight glass as the diffuser, and can put in your old headlights if needed. Cut the back off enough to be able to mount the LED board inside the back of the headlight body. Make sure you mount the board so you can aim it as needed. Seal up the back of the headlight with caulk and rubber or whatever works.

Would this work?

[Christ]

Probably not.

While it's a great idea, and is the best way to build LED panels for lights that don't light the way, so to speak, the optics of headlights are designed to take light from a single point and focus it on a single point further back, it seems.

Of course, I guess this isn't necessarily true, either, because many lamp casings have a diffuser in the front so that the only light that gets out of the lens is reflected off the housing.

There is a thing about rounded top LED's that you can narrow their light output or expand it by changing the shape of the resin that the diode is encased in. If you file the top off, the light output is effectively straight out only. Not sure how that could help or hinder the experiment, but it may help with light focusing.

Are you interested in trying it? I'd like to see the results if you are!

I do have to ask, though - Is it just the lens that's DOT approved, or is it the entire light assembly? Please, if you're going to answer this question, I'd like to see some reference or data of some sort that proves one way or the other, not just a thought.

[wagonman76]

I would like to hear other's thoughts too but I would like to try it.

I know with a light bulb, light goes out in all directions. The housing is a parabola shape and collects whatever spills backwards and sends it all directly forward. The light that doesn't reflect off the housing can still go all which ways out the front of the lens. So I would think the diffuser in front of the bulb would send all that forward light backward to the housing so ALL the light ends up going directly forward. It's either that, or the diffuser in front of the bulb is there to avoid there being a really bright spot in the center of the beam, rather it spreads that light out over a wider area to reflect off the housing.

With LEDs it would already solve the problem of having to collect the light going backward, since there would be none.

If the diffuser in front of the bulb is there simply to avoid a bright beam center, and the light is OK to go out to the sides some, then LEDs alone would be fine since it would be an even light output over the entire square.

If the diffuser in front of the bulb is there to block the light that can go all directions and focus ALL the light directly forward, then filing the LEDs would so the trick. Seems like the best way would be to solder them all in place, then run the LED board over a flat sanding block.

Without filing the LEDs, light would go +/- 20 degrees according to the LED specs. That may or may not be a good thing, one would have to try it both ways.

Not sure about DOT approval. However my thought was use stock headlight bodies for a built in diffuser, an easy mount, keeping weather out, stock appearance, and easy reversal if needed. I would think that law enforcement wouldn't hassle you as long as they're aimed correctly, and according to calcs they should be a similar light output to other approved headlights. They would probably just look like the whiter lights of more expensive cars. I think what the cops are looking for is people who are using those super bright off road lights.

I do have one question. You wire four 3.3v LEDs in series so 13.2v is needed, which is close to alternator output. So why do you need a resistor?

[Nerys]

to control current - wiuring series controls voltage while the resistor controls current. led's are current hungry give them current they heat up which makes them draw more current which makes them hotter which makes them draw more current - get it? till they melt down.

so you have to regulate the current to stop this runaway effect.

[jonathan150cc]

When dealing with LED headlights in general, why not aim the diodes away from the road, bouncing them off of a highly reflective rear cover that would work as a diffuser and an aiming mechanism. It seems to me it would limit the problem of being a very directional light. Enough LEDs would give very bright light while also being diffused and spread out over a larger lighting area area, like a standard filament bulb.

The design would be something like that of high beams on a tradtionally lighted car.
/ --------------------
l D )-------------------
\ -------------------

Something like that....

The "D" would be the LED while all other symbols would bascially be mirrors...

[Christ]

Originally Posted by jonathan150cc

When dealing with LED headlights in general, why not aim the diodes away from the road, bouncing them off of a highly reflective rear cover that would work as a diffuser and an aiming mechanism. It seems to me it would limit the problem of being a very directional light. Enough LEDs would give very bright light while also being diffused and spread out over a larger lighting area area, like a standard filament bulb.

The design would be something like that of high beams on a tradtionally lighted car.
/ --------------------
l D )-------------------
\ -------------------

Something like that....

The "D" would be the LED while all other symbols would bascially be mirrors...

Kinda hard to fit 120 LED lights and 450ish mirrors into a common headlight housing, I'd think.

Wagonman76 -

I say go for it. I'll consider it on my next vehicle, since Cara is no longer an option for modding (totaled, being picked up at some point when I get my insurance check).

After some more thought, I'm fairly certain you're correct about the reflector pattern of the light housings. I'd want to be sure to mount the LED's on a reflective (mylar?) surface, though, because the diffuser lens will partially reflect light back toward the mounting plate. Best to salvage every photon we can, yea?

I'm interested to see your results here. I assume you'll be doing this with a spare square light? (From one of your GM vehicles.)