Author Topic: LED Headlight Retrofit: It's possible! (Read 6058 times)

Master · « **on:** July 21, 2007, 06:54:17 PM »

Sorry if this is not knew to you but I found this quite interesting…
The main reason of me writing it, is the law they passed in my country, which requires to run with low beams turned on all year round and thats not a good thing…
So this is the info I found out so far which may benefit me and you:

Luminosity of standard vehicle lights

H7 bulb - 1100 lm 20 lm/Watt
HID bulb - 3300 lm 90 lm/Watt
Modern LED - up to 300 lm per LED, and up to 100lm/Watt !!!

Well I have given it about 30min of thought but I already imagine a LED low beam conversion FTW!

Hope you share my excitement, and your thoughts about this…

Ok to convince you this idea is viable here is more food for thought:
If we would replace a standard incandescent bulb and chose to go with about 10 LED's it would give us ~80% more brightness (I chose 200 lm / LED @ 1000mA for this example) while using only ~25W of energy
Ok, so if we decide to do a group buy of LUXEON Rebel LEDs that would cost us 4.4$ per LED in 250 unit quantity 6$ otherwise
So if you do the math that's 88$ in LEDs minimum (2 front low beams counted), BUT it's much cheaper than HID (correct me if I'm wrong) and you won't have to change them in your life time guaranteed…

But there is also the aspect of making them fit into the head light, as well as putting them together, and I guess ellipsoid headlight owners are the only candidates for this swap, because I don't think the light could be focused properly in a standard reflector bulb…
A voltage regulation circuit is also necessary, but can be easily designed for 2-5$ (have the diagram if anyones interested)

Some usefull info:
http://en.wikipedia.org/wiki/Luminous_efficacy#Lighting_efficiency <-a bit outdated
http://www.utzverlag.de/buecher/40257dbl.pdf <-outdated but relevant
http://www.lumileds.com/products/luxeon/ <- LUXEON LEDs

So there's lots to think about, share your thoughts on this…

asubimmer · « **Reply #1 on:** July 21, 2007, 07:15:29 PM »

that seems like a good idea at first but you've overlooked a small but importaint detail. While LEDs are very bright up close they do not projoject their light as far as your standard bulb. You MIGHT be able to get away w/ LEDs in your fogs but I wouldn't want to.

Master · « **Reply #2 on:** July 22, 2007, 08:12:44 AM »

Quote from: asubimmer;30080

that seems like a good idea at first but you've overlooked a small but importaint detail. While LEDs are very bright up close they do not projoject their light as far as your standard bulb. You MIGHT be able to get away w/ LEDs in your fogs but I wouldn't want to.

How can a light source that is brighter not shine further?
I think it's just that LEDs have a small angle at which the light is visible, so a lens/diffuser needs to be used to spread the light in the places you want�

nuvolarossa · « **Reply #3 on:** July 22, 2007, 08:32:13 AM »

This things make me think... here too we should have low beams all day.. do you posted this in other forums too? I'm starting to think a custom headlight for e36s...

maybe leds only for daylight...

some links:
http://www.ledsmagazine.com/features/3/7/5
http://www.ledsmagazine.com/news/3/1/8

White LEDs are used in the daytime running lights on the front bumper:

leds in foglights
http://www.instructables.com/id/EVIV78PF1B3RH1U/
http://www.youtube.com/watch?v=q1stfvbUIpQ&mode=related&search=

Master · « **Reply #4 on:** July 22, 2007, 09:32:39 AM »

Quote from: nuvolarossa;30114

This things make me think... here too we should have low beams all day.. do you posted this in other forums too? I'm starting to think a custom headlight for e36s... maybe leds only for daylight...

Thanks for the links!
No I haven't posted at other forums yet

We think the same

Master · « **Reply #5 on:** July 22, 2007, 01:19:30 PM »

Ok people I've started a thread on bimmerforums to see if we can get some momentum going:
http://forums.bimmerforums.com/forum/showthread.php?t=793158

Master · « **Reply #6 on:** July 22, 2007, 03:56:02 PM »

OK, after more thought I think it would be better to use the same Luxeon Rebel LED's but @ 1.5A per LED. This should give us an output of 300lm per each LED, although at a cost of lower efficiency ~60lm/W
So we would only need 5 LEDs per side, and still achieve better lighting ~30% higher and ~27W of power consumption

The cost for the conversion would lower dramatically (~50$ total)

gearheadE30 · « **Reply #7 on:** July 27, 2007, 09:19:08 PM »

By the way, the new Audi R8 can be had with LED headlights. It is the first production car to do so.

Master · « **Reply #8 on:** July 28, 2007, 12:07:27 PM »

I think Saab also has a car with LED low beams.

BTW I ordered 2 some of the brightest single chip LEDs (Seoul P4) 240lm capable, and will try to do a DLR mod with them…

bmwman91 · « **Reply #9 on:** July 28, 2007, 08:35:06 PM »

I am watching this intently. Hopefully you will have good results!

jpod999 · « **Reply #10 on:** July 28, 2007, 11:36:58 PM »

Doesn't the new Lexus LS460 have LED headlamps?

gearheadE30 · « **Reply #11 on:** July 29, 2007, 03:29:42 PM »

The euro one does iirc. The US variant doesn't because they aren't DOT legal.

BTW how much were the LEDs?

Master · « **Reply #12 on:** July 30, 2007, 04:16:04 PM »

Quote from: bmwman91;30648

I am watching this intently. Hopefully you will have good results!

Hey, thanks!
After doing some research at various LED forums around the web,
it became clear to me, that a full low beam conversion isn't quite practical yet.
The technology is almost here, and it's quite possible but not practical.

There are a few options if going full low beam conversion (at least it's how I imagine it):

-Use ~6-7 Lumileds Rebel LEDs surface mounted on LARGE heatsink, a
nd drive each of them @ 1Amp current,
so each one would be outputting ~200lm.
Some kind of active cooling should be required in this case,
as their efficiency would be about 63lm/w

-Use ~12-14 Lumileds Rebel LEDs surface mounted on LARGE heatsink,
and drive each of them @ ~300mA current,
so each one would be outputting ~100lm.
Active cooling may be required for those very hot days,
as the efficiency is this case is quite high @ 100lm/w

-Use this monster, and worry even more about cooling,
as efficiency of this monster, well, sucks just @ ~34lm/w

Non of these options is easy, because in each case the total vdrop across the LEDs is more than 12V,
this means wiring them in parallel, which requires additional voltage/current regulators, hence more complexity,
also I don't think any of these options could be cooled passively without requiring a massive heat sink,
or some modern technology like heat pipes.

Also fitting all this in the beam assembly is quite a challenge, even in case of the e36 beams, which have quite some room.
The other challenge is "conditioning" the light produced by the LEDs before it hits the stock lens.
As LEDs produce quite a concentrated light, some kind of optics should be used to spread it out more evenly.
But this is quite possible, because wide angel lenses are common for popular LEDs.

There are ofcourse other problems that one will encounter, if taking on this challenge.
But it is possible, I know at least one guy who did a full High/Low beam conversion for his friends truck,
and I can link to his thread if someones interested, although, the server with his pics is down,
so there is nothing to look at except some 15 pages of boring text.

I personally still believe, that in some 2-3 years such conversion would become even more practical,
for now though, using LEDs for anything more than DRLs is not quite practical IMO�

Master · « **Reply #13 on:** July 30, 2007, 04:24:58 PM »

Quote from: gearheadE30;30681

BTW how much were the LEDs?

Well, I paid 10$ for the LED stars a piece, and 4$ a piece for some optics to play with, so thats 28$ +2$ shipping in total

Probably not the best price, but not the worst by far, and the seller was really fast to ship them, so I'm expecting them to arrive any week now