DIY LED car headlights!

Step 12 Continuing on Phase Two...

That's about definition enough: I'm continuing this project.

The first image shows how things look right now: two upper 'edge' arrays, each with 21 5mm LED (pointed forward, 5 degrees down and 5 degrees outwards), a central array of 60 LEDs at top density (pointed straight forward, replacing the twelve LED array around the Hyundai symbol) and two lower 'edge' arrays, each of 24 5mm LEDs (pointed about ten degrees down, five degrees inwards). Not counting the eighteen LEDs that sit under the hole where the Hyundai symbol used to sit, the array is consuming 10.5 Watts at the LEDs, 1.6 Watts at the resistors and draws precisely 1 Amp (1000 mA) from the source.
As of July 1º, the last modules have been in place for a week and a half and it's been raining so hard that my car even looks like it had been washed: if these modules where about to fail, they would have already done so.

The Second image is a working image on the construction of the Upper 'edge' LED modules. They are mostly the same as in step four, except that I painted the boards before starting to work.

The Third Image shows my building of the center module.

The fourth image is a close-up on the capacitors I scavenged out of an old computer's power supply and connected to the central array. I used an scavenged bridge diode to isolate these caps and their array from the rest of the car and, of course, I had to tweak the resistor values for the central array.

The fifth image shows a couple of octagonal mirrors which I fitted into the hole for the central array. Not that useful, but they push out an extra little light.

The sixth image is the test of the array under the same conditions as always. I will need to reach the 300 mark before the light is good enough, but I'm glad that with only 102 actually pointed to the front, I do have decent illumination.

I have decided That I will need to have a third phase, composed of Luxeons or such High Intensity LEDs. Don't hold your breath, though: I first need to finish the second phase, them learn how to work Luxeons.

Comments

[diego_sathanae]

 oye amigo eres de mexico verdad? podrias ayudarme con un proyecto similar es que yo quiero aprender a hacer tiras de leds y la verdad es que la verdad nunca e hecho nada con leds pero realmente tengo la inquietud de poder manejalos algun dia y me parece fantastico tu trabajo. ojala me puedas ayudar te lo agradeceria mucho.
ATTE. Diego Soto A.

[Kirk]

http://pdfserv.maxim-ic.com/en/an/AN3256.pdf
you may find it interesting

[crash138]

 well after finally seeing your headlights I know why you needed the extra lighting... goto walmart and get some of that polishing compound for your headlights!  They are so cloudy you are probably at 10% of what they should be...  Id have just bought some driving lights to put on, but the leds are cool, prolly woulda mounted them in the weather proof boxes, with "Tamiya" style connectors for easy removal....

[glenjhor]

you're damn good!!! you got skills bro. can you do under car led lights? can you tell me how? i dont have a background in electronics..

[Shinji]

LEDs are simple to use. If you want any help on using them, just email me at [e-mail] and I'd be glad to help you if he would rather not.

[cancelli]

Hi Shinji, do you know what LEDs are used in the latest Euro auto tail lights, I'd like to build similar arrays into my Fiero tail lights.

[Shinji]

I'd assume that you just want to use some 6000 mcd 5mm or even 10mm red LEDs, those are so cheap on eBay of course. Even in stores, also. For tail lights, I would recommend 10mm LEDs probably, as they don't focus the light quite as much and provide a much larger red dot when looking straight on. Make sure you get them with 12v usage resistors, of course, unless you find some 12v LEDs (which do in fact exist). If you didn't know already, the "mcd" rating is minicandella, or brightness. Since you don't want utterly blinding tail lights then you won't want to go any higher than 6000 mcd. Just make SURE that you don't buy any 3mm LEDs, those are too small, honestly. For tail lights at least. If you have any other questions, feel free to ask.

[cancelli]

Thanks for the info Shinji, I,ll have a look for some suitable 6000 mcd LEDs and have a go at working out a circuit that gives the two levels of brightness.

[Shinji]

Yeah 2 sets of resistors would do that well, I'd hook one up to a battery with a potentiometer, and go up in brightness (down w/ resistance) until it's where you desire it, then test the resistance of the pot with a miltimeter while out of the circuit and pick the resistors up from your local electronics place. Remember to use 1 LED per resistor, or they will over heat (the resistors).

[nerys]

This is not quite right Shinji if I am reading this right. LED are rated at Milliamps You should never exceed this. BUT this is not the end. The "rated" ma assumes adequate cooling. Adequate cooling is considered 9cm/2 of cooling surface area PER watt of LED consumption. Your tail lights have NEGATIVE cooling Not only is there No cooling surface area but you are ENCLOSING them. I would "start" by doing this. Set up your potentiometer and set the LED for HALF there rated MA ready to go inside the housing. Pop and digital thermometer in there and place this in an environment that is typical for where you are If your in mexico I would shoot for 80' F in 20 minutes CHECK the temp. if its over 100'f inside there your running them too hot turn down the power. Keep adjusting this till they stop overheating. You do NOT make LED's brighter by using more power You make them brighter by using MORE LED's Now that you NOW know the proper resistance you need use the SAME kind of LED from now on and the same resistor. Brightness with NUMBERS not Amps. DO that and your LED's will outlive YOU. I illuminate my entire bedroom with LED (and the bathrooms working on the rest of the house) I use 2200 LED's to light my bedroom and consume only 27 watts. When I got these LED tubes off ebay (198led in each tube) they Fried themselves inside 1-4 months turning "blue" inside 3-5 weeks nd dimming till they died. He was running them at 12 watts. They were incredibly bright but useless with such a short lifespan. They were hitting over 160'F inside the tubes during the summer!!! I installed a Variac so I could lower the voltage (lower the voltage by ohms law you also thereby lower the current draw) since taking them apart was not an option. Worked a treat. Half as bright (so I double the number of tubes) and now they never go higher than 10'F above ambient. 8 months and counting No dimming or color shifting. Do NOT over drive LED's your just asking for trouble. Even if you SEAL them to waterproof them water cooling is an issue since you can not use the radiator. The green color of your radiator fluid will make your lights green and the coolant temperatures are far higher than the safe temps for LED's you would need to design your own separate distilled water cooling system for them. Thats a lot of work and effort. Lot easier just to lower the current and add more LED's in the long run.

[tomfarr]

Excellent stuff, nerys. I came here looking for info on the feasibility of using LED's the headlight on an electric motorcycle. Lighting your home! I like it!

[Shinji]

Ok, apparently you misunderstood me... For one, the LEDs to be used in car tail lights are not high wattage! rated in mW, they do very very little to NO heating up as they work. That is to be expected, as they are LOW WATTAGE LEDs. And did you know, Luxeon LEDs do not need 9 cm/2 of aluminum to remain quite cool. LEDs will heat up IF you overpower them, in amperage that is. Such as, you stick it on your PSP battery or your mobile phone battery. With the setup we are discussing here, water cooling is absurd to say the least and having all the LEDs connect to a large heatsink is unnecessary indeed. With the LEDs in your room, how'bout you try JUST limiting the current in to the setup? Put a current limiting resistor in-line or something, but getting LEDs to radiate 160 deg F is incredible. Also, remember that the LEDs used in Christmas lights do not have heat sinking any more than the car setup. You don't need to cool 6000mcd LEDs unless you are overpowering them, in which case they will not last long at all anyways. And yes, in car applications you would refer to the nominal voltage as 14.4v, while the batteries themselves are truly 12v. As long as you make sure the voltage in the through circuit (meaning while the LED is running) does not exceed the rated and not maximum amount for sure, and you put a meter inline to monitor mA, also making sure it does not exceed the LEDs maximum allowed current, they won't overheat. Also, what gave you the idea that you would want to pull out some random LEDs from your closet and do the testing with them?! You should always test circuits with the components to be used in the final circuit to be sure it will perform the same way. Final note is, cooling this setup is not a matter of importance. You should run LEDs at nominal voltage with the current being regulated. However, because this is not very easy, you would lower voltage to lower brightness while still keeping current low.

[nerys]

Well this may "work" in this usage scenario but its definately not correct for all scenarios. If you put 200 White LED in a Polycarbonate 1 inch tube seal it up and run those LED's at the PROPER wattage they can and will overheat. The problem is white LED's get there color NOT from the LED (which is BLUE or even UV) but from the Phosphor that converts this light into WHITE spectrum light. NOW when LED's get too hot they "burn up" this phosphor and turn blue in color. Here is where the problem start. When LED increase there temperature they increase there resistance and want MORE power. This starts the nuclear melt down for LED's and is WHY you have to current limit them. Normally this works fine but sometimes you get a bum resistor thats not quite to spec OR you get a bum LED that fails prematurely freeing up AMPS for other LED's to consume. NOW suddenly your over your amp limit. Just by a tiny bit but over nonetheless. This starts a domino effect. this extra watts makes this just a bit hotter maybe enough for yet one more LED to fail prematurely. Little hotter little more failures etc.. etc.. Also the "rating" for LED amps is with the assumption that they are properly cooled. When your running a SINGLE led such as in christmas lights the entire LED is effective "cooling area" so you do not have a problem. The problem comes when you start GROUPING led's which is reducing there effective cooling area. As you group LED's together you need to increase cooling. NOW in your "strips" configuration your not going to have any problems. all the LED are essentially dangling in the wind. BUT as you found corrosion becomes a problem so your needing to SEAL them up which is also going to "INSULATE" them which may require some cooling or it may not your still running only small number of LED's Now once you start putting large quantities of LED's in an enclosure like your tail light fixtures your may start encountering some heat problems. Depends on how many and what power LED's you use.

[Shinji]

Oh and BTW amperage does not push, it gets pulled. If you take away 1 LED,it will not really "free up amps" it just dies. If all the others have a resistor on them, you will not have a problem with amperage! The circuit is not using up all the amperage available from its power source, or you have a WHOLE lot of LEDs. And another bit, the LEDs in our lights are not sealed in a tube, and so they do not suffer from the same problem of an incredible amount of insulation.

[nerys]

Really got to read the message man, I SAID when you DO led's in SERIES (this by definition means you DO NOT have a resistor on each LED) then I am 100% correct you WILL increase the amp load on the other LED's if and when one DIES. I have plenty of DEAD tubes to show for this :-) YES the correct way to do LED's it to wire them parrellel with a resistor for each but this adds a ton of cost and work hours to make them.

[Shinji]

When you buy LEDs off of eBay you can always find packs that include resistors. If you have 10 LEDs in series and one blows AND stays connected inside so it keeps the circuit going, the other LEDs will get more voltage and amperage draw will also increase because of the mroe volts. However, if you have 10 LEDs in paralell and 1 blows, the others will not draw more amperage. That is my understanding on what you described before, that the LEDs were in paralell not series.

[nerys]

it must just be a language barrier I was pretty clear about it being series wired. Parallel (as I already stated as well) is the right way to do it but its very expensive in materials and labor so MOST people wire them in series to some extent. This is where the meltdown issue comes into play when one fails (if it fails "open" all the led's in that series will turn off since its now an open circuit :-) they almost always fail closed I have actually never seen one fail open. I am going to have to run some more tests on this area versus brightness issue you bring up. Every time I have added more LED's "brightness" as increased. Area on increases slightly since all the LED's are in one relative location. You "spread" led's out if you want to cover more area. Are you telling me that when you have multiple LED's aimed at the same spot that its no brighter than when you aim one at the spot? I actually have 7 of the same LED flashlight 3 LED flashlight on 3 AAA at the dollar store!! I bought all they had :-) anyway when I shine more than one on a spot it gets progressively brighter as I add more Flashlights to the spot eventually it stops getting brighter (after 5 lights) but that only because its now bright enough that it looks pure white and I can perceive no more brightness in such a small area. Remember short of some odd ball car your tail lights are not very large. If you put 10 led's together and 50 led's together the 50's are going to be far far brighter and far more noticeable and from a larger distance than the 10 are. No different than your 6w and 21w difference bulbs. IE 10 .1 watt led's will put out the same brightness as a single 1watt led (this is actually not true most of the time many times the 10 .watt led's will be brighter than the 1 1watt LED efficiency issues but for this discussion we can ignore that) If there light production efficiency is the same. IE if the .1 watt puts out 10 lumens and the 1watt puts out 100 lumens 10 .1 watt's led's will put out a combined 100 lumens 1 watt in 1 watt out. IE Light is CUMULATIVE not static. AREA coverage has nothing to do with brightness. Thats just a measure of how you DISPERSE the light. I can put 100 led's together and cover a very small area with blinding light IE spot light OR I can spread 100'led out and get more coverage at the cost of percieved brightness ie flood light. SINCE all the LED's are going to be inside a space less than 5 inches across its going to retain its SPOT qualities and its going to be very bright. NOW if you spread the led across the bumper SURE its not going to "appear" to be nearly as bright. Brightness is PURE lumens and lumens are cumulative. PERCEIVED brightness all other factors equal is just a measure of FOCUS spot/flood etc..

[Shinji]

Yes what you explain about lumens is correct, the issue I am discussing is easily explained like this; if you have 5 very dim LEDs and shine them all on one spot, the spot will not be brighter than if you could focus all of one of the LEDs energy and light onto that one spot, with no distance loss and spreading, in sort of a laser concept. Hard to explain, but you see what I am getting at? The busses use the same LEDs for bright and dim, but thats a cicuit I'd rather not come up with (although if thats the way cancelli would rather his lights I'll look into it). However, if you had a dim LED and a bright one, of course the dim one would be harder to see from distance, but the 6w fillament is still lighting up the taillight and making it look like a really big but dim light. That's what you want to acheive with the LEDs, but since they focus straight and not on the reflectors in the housing of the tail light, you need to use enough LEDs to increase the visible area just like the reflectors do, you know? instead of some little star spots inside the tail light, have there be as many dim as bright LEDs and you will cover more surface area inside of the light housing. Thats the point I'm making here, because that would be a softer and easy to see way of doing this. You could also, in essence, make a 6x brightness set of LEDs by just simply buying some 3000mcd LEDs that include resistors for use w/ 12v and then for the 21w part buy 1000 mcd LEDs. Just wire 'em up and then you will have dim and bright fillaments, so to speak.

[nerys]

?? well thats no different than regular bulbs? you buy the LED specific to your needs. You can get LED's from 10' spread patterns to 180' spread patterns and you can use reflectors JUST like you do with normal bulbs. In fact JUST putting the LED at the "front" of the fixture on the inside back of the fixture INSTEAD of right against the transparent portions WILL give you the desired spread you want. It all depends on where you put them and WHAT kind of LED's you use. Spread is a non issue. Just like you select the right "reflector" for your incans you select the right SPREAD (since the reflector is built into the led) for the LED's you want.

[Shinji]

You aren't thinking in the right application. More LEDs will help cover more surface area in your bedroom, but this is not a room we are trying to light. We don't want to light up the road, we want people to see when we brake and such. Do a little experiment for me: go to a grocerie store, buy a rip-off pair of LED flash lights, and shine one on the ground. You can even use incandescent flashlights if you want, they just have to be exactly the same in batteries and light bulbs. Now, shine the other one on the same spot. Notice how the spot doesn't get brighter? That's because of the properties light, and that's why there aren't a thousand lights in 1 room of a house. You are just trying to cover surface area with equal light, because the ground will never be brighter than the 60 watt bulbs that light it, even if you have 100 of them. The tail lights need to be lit up by the dim lights, not half or a third of the light, because that's what you're going to see if you dim with the LED count. Experiment with that, too, because I did and using 10 LEDs for a dim light and then using 30 LEDs for a bright light doesn't work, it just makes the light easier to see. Trust me on this, or go try it for your self on a real car, not a bedroom ceiling, and you will get it. Also, of course you would use the same resistors for each display, because thats how you explained it earlier, so you would use the PROPER resistor for the display. By PROPER, I assume you mean something close to the nominal resistance to obtain the nominal operating voltage for the LED at the LED's nominal current draw at nominal voltage. You need to dim the LEDs, not lessen their quantity. That only makes it harder to see the tail lights on your car, which is quite contrary to their purpose I thought. As far as cooling goes, try it. As I said before, I did, and as I noted, they did not heat up. Not even close to being significant. The wires act as heat sinks, the plastic tail light housing acts as cooling if you really want to think of it that way, and IF your tail lights are exposed to elements of sorts, and this is always a good idea if the LEDs wouldn't be inside of the lights outer housing, apply an appropriate amount of silicone caulk. you will STILL not have heat problems, and if you are really still worried about heat, ground all the cathodes to a strip of metal. Aside from that, you don't need tons of LEDs, especially if you go and use 10mm LEDs and sand the tops to diffuse them and make them easier to see from all angles (as LEDs are mostly a lens, and focus straight and not around the edges very much). You only need enough to evenly cover the surface of the reflector in the light's inner housing. lowering voltage lowers amperage draw and lowers heat AND lowers output from the LED. Same amount of LEDs for dim and SAME amount for bright. thats how it needs to be, it needs to be easily visible and most prevalently, SAFE. Change the resistors for each set to change their brightness, just like you did in your room.

[nerys]

I have been working with LED's for some time the biggest problem is always lack of cooling or too much power. If you adjust POWER properly cooling is never an issue. You never power led's by rating you power by cooling but never over the rating. I am not sure I understand about your surface areas description. When I light 10 LED's on a spot on the ground and then I light up 50 more of the same LED's on the same spot the spot on the ground gets significantly brighter?? IE if you put 30 LED's in your tail light its going to get a hell of a lot brighter than 10 led's ??? (at least in every example I have ever seen it is) NOW if you wire those 30 led's into the SAME circuit as the 10 led's well yes its going to be the same brightness over a larger areas because you are now running all of them at 25% of there normal power. (giver or take other factors but youi get the idea) the 30led's need there OWN circuit ie those 30 should be consuming 3 times the power of the 10 if there all the same LEDs ie a different set of resistors etc.. for the 30 etc..

[nerys]

Also cars do NOT run off 12v We "call" them 12v batteries like we call hook and loop tape Velcro. For "electrical purposes" then run typically at 13.8volts !!!

[cancelli]

That's a good idea, I can check the levels against a normal bulb. Can I use individual resistors to set the brightest setting but only one higher wattage resitor to control the lower brightness setting? (obvously in series with the combined LED resistor matrix)

[Shinji]

You can use one high wattage one for both, if you can find one that resists enough that is... The idea of a bunch of resistors requires that one end goes only to an LED, for each resistor. You can't connect resistors in parallel because that cuts the resistance. 2 resistors of the same ratings put in parallel = 1/2 the resistance of one, and son on and so forth. In series they would just keep adding up in resistance, so just one per LED. Or just a high wattage one, of course. Voltage x Current = Wattage

[nerys]

Ideally yes one resistor per led. YOU CAN calculate the resistor needed to run Series (harder for Cars since you will reach 13.8v fast much easier for 120v systems) but there is a problem. If an LED fails and ceases to draw current you now have MORE current available to the rest of the LED's in that series. IE you can a cascade failure like domino's. This is why parallel is preferred.

[cancelli]

Sorry, I didn’t make it very clear, what I was trying to say was that if I make up an array of LEDs each with its own dedicated resistor, as you suggested, it would in effect become one 12v light unit, set to the brightest setting i.e. a brake light. I was thinking I could possibly just switch in one higher wattage series resistor to dim the brightness of the 12v unit to tail light level. The idea being, to bypass the dimmer resistor when braking. I’m trying to avoid using 2 dedicated LED arrays in one unit to provide the different levels for brake and tail because it would be difficult to get the light pattern right

[Shinji]

I don't think we are on the same page... One set of LEDs, not seperate sets, connected to a set of resistors, or one big super-watt resistor, and since the car does all the dimming by its own self, you only need one set of resistors or one big one that make the LEDs the brightest that they can tolerate at 12V. So when you hit the pedal, they will go bright and when your headlights are on, I assume they will go dim. If your brake bulb is a high and low beam type, then just connect the 2 resistors up to the + terminal of the led, and use the higher resisance resistor for low beam/dim, and the low resistance one for high beam, all with a common ground.

[nerys]

The easiest way to handle this is to GET IT RIGHT once and stick with that. IE figure out the resistance and never change. Adjust brightness with LED's not current. SO for example if 50 LED's is enough for a tail light install 100. 2 sets of 50. ONE is one with park lights and when you hit the brakes ALL 100 Light up IE the second set kicks in. doubling the brightness. This is how your current lights work. (that single bulb if that is what you have is DUAL filament thats why it has TWO contacts on the bottom) brakes off ONE is lit brakes on BOTH light making it brighter (some cars use 2 bulbs some use 1 double filament bulb IE 2 bulbs in one glass ball) Do the same with your LED's a lot less hassle and you get to use the existing wiring controls etc.. and once you have done your testing you know they won't overheat or do something else goofy (see my posts higher up)

[cancelli]

Double filament 21watt/6watts stop tail light bulbs don't work like that in the UK, the two filaments work off different circuits, 21W is operated by the brake light switch, the 6W by the light switch. There is no interaction i.e. braking cannot light both filaments to increase brightness. The almost 4 time higher wattage filament is why the brake lights are much brighter. I have studied the new bus and truck stop/tail lghts which have a matrix of 50 or 60 LEDs. All the LEDs are lit at a low level as tail lights but the same LEDs become very bright when the brakes are applied. This is what I want to make up to customise my Fiero lights.

[nerys]

Irrelevant really the result is the same for our purposes you have TWO filaments. The 6watt filament (at least mine) do not turn off when you press the brake all pressing the brake does is activate the second filament. YOU can do the same with LED's so you use 25 for running lights and have the brakes activate another 50 or however many you want. IE no reason to use different bulbs just more of the same bulbs. Keeps the math simple and the economics low :-) Point is you already have 2 circuits in place for this purpose. Just use them. To get your different brightness just use more LED's

[Shinji]

If your car does not turn the other filament off when you brake, its going to be a problem as the LEDs will be overpowered because of 2 sets of resistors in-line both providing voltage to the circuit. 2 sets of LEDs would be the easiest way, with larger (higher resistance) resistors on the set designated for running lights, and smaller/lower resistance resistors on the brake lights. Test as mentioned earlier, making sure that at no time the LEDs are over powered by voltage and/or current, and you should use the same # of LEDs for each set to ensure your lights are evenly lit and easily visible. You should NOT just use fewer LEDs to stand for dim running lights while you use more for braking. This simply will not work. The tail lights will not be as easily seen by other drivers and what's more, the tail lights won't really be dimmer in the desired way, just harder to see. If you use 25 lights for the running and 50 for the braking, people might think you are braking the whole time, or it may not look very different when you ARE braking so the y might not think that you are. You aren't lighting up a room here, think of it as an 8 digit display. if you use 1/3 of the segments for dim and then just power the remaining ones up for bright, all you see is gaps filled in. Now if you power ALL segments and dim them for dim and brighten them for bright, the difference is easy to tell. The tail lights are there for you and other drivers safety, don't cut them short. Not to mention the police, you don't want them questioning your hours of work putting in these new lights.

[nerys]

What are you talking about ? why would the second set of properly wired and resisted LED's ever be overpowered no matter how long they are on? NO not larger or smaller resistors. PROPER resistors. You do not adjust LED brightness with resistors.You adjust brightness with MORE or LESS properly resisted LED's YES it would work. You use WHATEVER number of led's is needed to get the PROPER brightness for parking lights and then ADD whatever number of LED's are needed to get the proper brightness when the brakes are applied. 25 and 50 where "out my butt" numbers just for the purpose of explanation. The actual number of LED needs to be experimentally determined and in case I missed something 50 LED will be TWICE as bright as 25 LED's YOUR led segment display is an illogical argument since #1 your talking a few low brightness displays and #2 they appear to you to all run on the same wattage. Your for some reason assuming I would run this extra set off the same resistors as the first sent CONTRARY to every post I have made about properly resisting them :-) YOU cut them short by making it more complex than needed and or risking LED dieing with improper power.

[cancelli]

Shinji, do you mind if I email you a daigram?

[Shinji]

Oh yeah, that would be real helpful. I assume you saw my email higher up this page: [e-mail]

[Nachoman]

Okay, I'll say it out right: On step ten (LED break lights) I used an 82 Ohm resistor per each series of 5 red LED's. If you do the math, you'll see that such resistor value is actually slightly higher than it should be; that's so the design has a margin for about 15% more voltage than nominal.