Luxeon Tail light. Any input?

[hizzo3]

I will be replacing the twin 1157's (28 watts a peice) i have in my tail light with leds. I figure luxeons would be the best bet. i will be using the stock lense, which has some optics built in. I will also be adding in a difuser, or maybe coating the luxeon lense with a simi transparent silicone to smooth out hotspots. that is the schematic so far. I am familiar with relays, but would rather use a solid state relay, as speed and reliablity are most inportant. Can anyone give me any pointers on them, since i have never used one b4. the reference from the buckpuck is 5V, the volt drop from the buck is @2v. lux I's in red like 110-350mA and 2.3-3.5v forward.

I will post pics of completed project.

 

[Oznog]

Luxeon is too intense a point source. The lens won't disperse it enough and there'll be one blinding point. Also, heat issues.

Best thing is an array of the 4-pin SuperFlux LEDs. Cheap, plenty of light, much less of a heat and soldering problem. The leg spacing will allow it to solder onto that prototype solder board from Radio Shack even.

Also keep in mind that usually you have a dimmer red "running light" that gets much brighter when the brakes are applied. So you might need 2 levels here.

 

[hizzo3]

sorry forgot to mention that i would be attaching them to an aluminum plate, and removing the stock reflector. my tail light face on my bike is roughly the size of a 3x5 note card. inside there is about 3 inches from back to front. i was hoping some frosted glass halfway between the lense and the emiters would work perfect to fix those hot spots.

I started to look at the superfluxes initially. i would need 40 of them. that would run me 30 bucks for that alone. then gotta do a PCB. I can get 4 lux I's for 2 bucks a pop. then artic ceramic them to an aluminum plate, and put on some wires, and coat them in liquid electrical tape.
Not only that, but the total array would burn 8 watts producing only 80 lumens. The luxes on the other hand will burn 5 watts producing 160 lumens. Since this is a motorcycle, i would rather have a lil on the bright side (not unsafe) then not bright enough (cant tell difference in daylight. which is why i start this in first place. the current led replacements suck). I really want the luxes if i can get them to work. too many benifits over the superflux.

as far as dimming, that is what the pot and the SS Relay do on the CTRL and REF side of the buck. the pot is set to a dim level, and when the brake circut activates, it switches the relay bypassing the pot giving full brightness.

 

[Oznog]

Luxeons cannot share a common piece of aluminum because the back is not electrically neutral, nor is it tied to either terminal. It is difficult though not impossible to get acceptable electrical isolation but good thermal conductivity with thermal epoxy.

Lamina makes some good products. But the BL2000 are still going to start the light from too small an area. Now Cree makes some GREAT SMD parts with an electrically isolated copper backing that produce a very impressive power level too.

Frosting will not have a dramatic effect without significantly more distance between the frosting and the lens.

I believe you may have miscalculated the strength of the SuperFlux. Which spec did you use? I believe even a dozen are more than enough light.

 

[justDIY]

a method I've seen recommended and used myself is to butter the back of the star with heatsink epoxy, a nice thin coat, and cover it with some plastic wrap (like saran wrap) ... then you can press the led onto a very smooth surface (like a window pane or mirror) and squish the epoxy to a very thin coat ... once it cures, just peel off the plastic wrap (it wont stick to the epoxy) and now you have an electrically insulated star... now just be careful with the mounting hardware used, so it doesn't end up shorting your heatsink to the star's backing.

 

[hizzo3]

i had used lumileds spec sheets. I guess i could use 20 superflux (keep in mind i have to do mulitples of 5 b/c of the voltage). i can do 20 for the tail and put in a 1/2 block of aluminum with holes drilled to "collect" the light a lil better(would that be needed?). then have 2 per side as side runners on a resistor based circut. should i do the tail off of resistors or use a buck. i think the buck would be easier since then i can use just one switch to change the dimness. Keep in mind efficentcy is the most important, along with reliablity. What angle super flux should i use?

 

[Hero999]

Where do you live?

In most countries it's actually illeagal to use DIY head or tail lights because they don't conform to the regulations.

 

[Oznog]

I think the wide SuperFluxes are fine.

Buck's ok but keep in mind if one string becomes disconnected, the constant current mode means that the remaining strings get more current.

The SuperTex HV9910 is a great little buck converter BTW. Very cheap, simple, and effective.

Resistors can be less than stable if there's no voltage regulator. For example, if you have a string with a total Vf of 10v, and try to power it with a battery which can be 12.6v sitting there or 14.6v when running, the current will vary by 1.77v, way too much. You could add a low dropout 12.0v reg and probably get great regulation.

I wouldn't worry about efficiency unless this is purely battery powered, no engine to keep it charged. A small motorcycle battery could power a taillight with resistors for many hours, days even.

You don't need an aluminum plate to disperse the light. The ones with a wide cast (most to 180) are fine. I guess anything 90 deg or more sounds right.

 

[justDIY]

like hero points out, you may run into trouble with The Man if you choose your colors wrong.

make sure you get DOT Yellow AKA Amber for your yellow lights and DOT Red aka Red-Orange for your red lights... regular super-bright yellow is too green and regular high eff red is too red, you'll get noticed quick. Lumileds products are already based on US DOT standards, so getting their amber and red-orange products is a safe bet, be it superflux or luxeon.

 

[Hero999]

Not just the colours, there are other regulations specifying things like the intensity, beam width and diffusion etc. I personally wouldn't risk it, I'd rather buy an off the shelf approved design.

 

[zevon8]

As pointed out above, this is pretty much NOT a do-it-yourself project. Not if you want to keep it legal anyways. Vehicle lighting involves fairly stringent rules and design criteria that fills several regulatory books, more or less depending on what jurisdiction you are in. For starters, as metioned above, colour, angularity, lumens, retroreflectivity of the lens and housing including surface area, are strictly laid out and must be followed. This subject was brought up before here, and I posted a link to one of the manufacturers, where a design sheet was given. If you can read photometric charts, and are comfortable with calculus, search for them.

I do trafic control equipment and emegency vehicle lighting for a living, trust me, there are rules for good reason.

BTW, 99.9% of those aftermarket LED tailights you see on the little sports cars, the ones with the clear lens?, all are illegal. Legit ones can be had, but they are generally 2 or 3 hundred dollars apiece, since the R&D as well as approval testing by standards labs to get certification does not come cheap.

 

[hizzo3]

Legality? since we are on that topic, there are no legal led drop in's. the only thing i can do is shoce a trailer light on there and remove my tail light.....hummm.... and for my next trick i will use duct tape for new hand grips.

There are some that are out there, but have a profit motive, nothing with saftey. search for 1157 led drop in. Come on 9 5mm red led's? now do u think those are legal, or how bout this, even safe? I would rather make my own, know its safe, wont fail, and puts out right amount of light. that is why i am on here. otherwise i would have done my first idea, which was 9 lux 1's set up like an acura TL's tail light. but i realize that wouldnt work, so i am asking.

Plus if i like it, and is ok in price, i may shoot for a DOT aproval. you never know. I may be the next custom part maker.

 

[zevon8]

Here are 2 links from Philips regarding use of Luxeon/SuperFlux LED's in this sort of application. And to be honest, it is really only the shallow end of the pool when it comes to what you will need to consider when designing a LED lamp system for an existing lens assembly.

All the LED lighting I use is DOT approved, albeit they are truck/trailer/emergency vehicle lights, but in all cases the lens is vastly different from that of a standard bulb. This is what greatly complicates your task... trying to get similar angularity and output from many sources when the lens was designed for a single source.

The only similarity is the reflector designed into the lens, and even that is somewhat modified to suit the new lens design. You will be going from a single point source with a dark cone of about 30 degrees to a planar array of who knows how many sources. Typically an array has a pillow lens, ( a separate lenses over each LED, ) designed to appear as an even distribution at a given distance.

The other factor is heat. What will you do to shed all that heat, especially in slow/stopped traffic when it's 100 degrees in August.

Many of the typical hi-output arrays use surfacemount wideangle lens leds that are heavily over driven via pulsed PWM. This cranks up the output but reduces the average heat generated. Think of those message boards over the highway, thats how they are done, bright enough top read in the sun, but use less power, create less heat.

What you want to do is feasible of course, but having to make use of the lens/housing you have is really going to make it complicated.

https://www.electro-tech-online.com/custompdfs/2006/06/AB20-1PDF.pdf

**broken link removed**

 

[justDIY]

lol, don't worry about the DOT, they're not worried about you

as long as your lights look the right color, no one will care. I know a lot of the members on this forum all want to be part-time lawyers or prosecutors, but come on it's really not that big of a deal

there are countless numbers of modified motorcycles and automobiles on the roads, none of which are legal as far as the DOT is concerned, yet the government eagerly accepts payment of license taxes for the vehicles anyway

in Michigan, the laws are about color, height from the road and location, as well as functionality ... so if your lights work, are the right color and in a standard location, you're all set.

 

[zevon8]

I almost forgot, the NHTSA / DOT #108 for vehicle lighting testing procedure is available online,

**broken link removed**

beware, its massive, 270 pages long.

 

[zevon8]

lol, don't worry about the DOT, they're not worried about you

as long as your lights look the right color, no one will care. I know a lot of the members on this forum all want to be part-time lawyers or prosecutors, but come on it's really not that big of a deal....QUOTE]

Yeah, really, after all it's just a tail light, pretty useless thing come to think of it. Who cares if the cement truck behind you on the highway has any clue that you are about to stop.

I bet there will be more than wanna-be lawyers involved if heaven forbid you are involved in an accident. Especially when the first words out of the other drivers mouth are " he had no tail/brake lights."

/rant over
ps I ride motorcycles and prefer all the saftey measures I can get.

 

[Oznog]

You guys are way too much into naysaying here.

As long as a taillight can be recognized as a taillight, has a decent spread (focused T1 1/3 pkgs are like a flashlight and project little light off to the side, even with a lens), and originate light in a distributed manner across the lens, you're good. Easy to be better. Just don't make the intensity obviously different than a taillight is supposed to be.

The regs are there to prevent orange, green, or blue taillights. Modders would inevitably do this otherwise.

 

[justDIY]

You guys are way too much into naysaying here.

I agree

 

[hizzo3]

The regs are there to prevent orange, green, or blue taillights. Modders would inevitably do this otherwise.

Man those are really anoying. the other day i pulled up behind a civic who's "altezza" tail light had faded from red to almost a yellow. and in the front he had dark blue blinkers. lol. since i am using the stock housing, not an issue.

i ride my motorcycle 90% at night. the main purpose of this mod is to free up juice for additional forward lighting, or a twin HID projector set up (would be doing it correctly, using already dot approved parts for the legal crowd). seeing as my bike is at a full drain at idle untill 2500 rpm, freeing the 50 some odd watts in the back seems very big when you only have a 350 watt charging system at 3-4k rpms, not to mention i wont have to worry bout replacing them. I also plan to swap out turn signals too. that is easy done with some wide angle optics and a single lux 1 per signal. seen it done b4, and looks good. Yeah a lil brighter then stock, but not blinding unless you are literally 2 inches from the turn signal.

anywhoot. I ended up with a spare tail light lense when i had it in the shop previously (someone hit it in my apt. parking lot, while it was parked, trying to swerve around speed bumps). I wonder if i can sand those optics out, for a smooth surface. That way i can just use the superfluxes plain or with some form of optic with no ill funky effects. Seems like it is maybe polycarbonate. i guess if i use a course followed with a set of fine-superfine wet sanding, i should be able to get it (used to paint model cars back in the day.) My other option is that i could use a clear coat and do a few layers untill smooth. i know the latter isnt better then the first, but would greatly reduce the effects.

 

[hizzo3]

Yeah, really, after all it's just a tail light, pretty useless thing come to think of it. Who cares if the cement truck behind you on the highway has any clue that you are about to stop.

I bet there will be more than wanna-be lawyers involved if heaven forbid you are involved in an accident. Especially when the first words out of the other drivers mouth are " he had no tail/brake lights."

/rant over
ps I ride motorcycles and prefer all the saftey measures I can get.

Well as seeing i live in dallas, more then likely the first word out of their mouth will be "i had to take that call." and yes i've already heard that excuse once when a navigator hit me in my escort. i couldnt even get the guy off the phone to get his info so i had to threaten calling the cops and report he was uncooperative after hitting me.

In my book. the more attention i can get to me the better. at least if they look up from their cell phone or in dash tv screens b/c of a brighter tail light, then mission accoplished, and my tail saved. Plus led's dont burn out near as often as regular bulbs in motorcycles b/c of vibration.