Jim Banville

Does anyone sell direct replacement CLEAR LED bulbs for our brake and turn signals? I've seen the ones that are clear when off, but are red or amber when lit, at formymercedes.com. I think a colored light behind a color filtering lens would diminish the overall brightness. I also understand I will have to mount some of those resistors with the LED.

vadim

No, brightness won't be affected too much.

Incandescent bulbs produce light in a rahter wide range of wavelengths (shorter = purple; longer = red, other colors fall in between; mix = white, more or less). In order to get light of a certain color, a filter has to be used that only passes through the light of the desired wavelengths, blocking the rest of the spectrum.

LEDs, on the other hand, emit light of a very narrow spectrum - monochromatic, with no other (unwanted) colors present. Hence, no filter is need. But if you use, say, a red filter on an LED emitting red light, the light will pass through just like it were clear glass, since the filter is supposed to pass wavelenghts from this area of the spectrum.

Harris

Ask Bagwell....ask me. We both bought LEDs from formymercedes.com. We both returned them.

vadim

The problem is, these LED bulbs are directional - they emit light in one direction, as opposed to regular incandescent bulbs. The brake light bulbs in the Coupe's rear light cluster are mounted vertically. Not a problem with a regular bulb - but this makes the light from the LEDs barely visible.

I've been thinking of designing a specially tailored light conductor that would redirect the light from the LEDs to the lens - they can be made from clear plastic. The principle is the same as that used in fiber optics - the light reflects from the walls of such conductor, staying inside it. You can bend it, thereby directing light as you wish.

Those who deal with rack-mountable servers, probably, have seen those. A good example is the one used by Dell to replicate LEDs on detachable front panels.

mleskovar

The brake lights on C sedans are incandescent. Are you suggesting replacing them with LED's? It would take several/many LED's to produce the equivalent brightness.

vadim

LED bulbs comprise many LEDs bundled together.

There are many online stores offering drop-in replacements for automotive incandescent bulbs:

http://www.trucknvans.com/bulbs/

http://www.theledlight.com/ledbulbs.html

http://www.stylinconcepts.com/parts....categoryid=198

Drew_ML

I recently installed the formymercedes LEDs for my brake lights. Yes, the load equalisers are required, but they are installed easily. No error messages on the display whatsoever. I remember Jerry at formymercedes saying that a few C owners couldn't get it working so some of you must have done something incorrectly as mine work perfectly.

They are darn bright when lit and the main point of getting these was that the bulbs would light up in tandem with the LED 3rd brake light, and not half a second slower. At 60mph (96 kph), that half a second equates to up to 20 feet of extra braking distance for the driver behind you.

Here's a picture that I just snapped 1/2 hour ago:

Matt230K

Are the bulbs only mounted this way in the coupe? Because it sounds like Drew did it with no problem on his sedan. I guess we'll have to wait for your invention that you can sell to all us coupe owners. I like the LED taillight look. You can definitely tell how much quicker they light up.

Drew_ML

It shouldn't make a difference whether it's the coupe or the sedan, or even the wagon. I've tried it on both the sedan and the wagon. However, I haven't tried them on the coupe and will say that if the brake bulbs are mounted vertically, then I would not recommend it as they would be too directional. The sedan and wagon both have bulbs facing backwards.

I should add that not all LED bulbs are the same. I've tested all of those that I've been able to get a hold of, from Alpena, APC, to Polarg. The formymercedes.com LED bulbs are by far, the best out there. They are literally blinding when tested even with a 9 volt battery.

Here's the wagon:

vadim

Actually, "brighter" isn't necessarily "better" in this case. A LED bulb can be easily made as bright as desired. There are LED-based headlight lamps out there already. As for the brake light - I wouldn't want it to be "blindingly" bright - it may actually work against you under certain conditions - rainy night, for example. If you blind a driver of a car behind you, it will hardly increase your safety.

Drew_ML

Yes, I know that. However, in this case, brighter is better as it allows for more light to be diffused evenly through the fluted lenses + the reflectors. The result is a pattern which is very even, and not simply two points of bright light as many LEDs are.

What I meant was that the exposed bulb, when held within a couple of feet to one's face, are blinding bright. Not all LEDs are that good. The Polarg & APC ones, in particular, were not very good.

In rainy conditions, and we get a hell of a lot of those in Vancouver, the LEDs are much more intense and vibrant than the regular incadescents. Not to the point of

Jim Banville

Thanks for the info Drew! Can you post instructions on how/where you mounted the equalizers, etc.?

thanks !
Jim

amdeutsch

Thanx Drew,

Any chance you can give some specs on this equalisers. Are they just resistors? If yes what is the value? If not, then what do they consist of: if you know?

Jim Banville

amdeutsch, the equalizers are around $7 and can be bought from formymercedes.com .

vadim

They are 6 Ohm resistors coupled with heat sinks. They have to be able to dissipate 30-40W, so your regular one from Radio Shack won't do.

amdeutsch

Thanx Vadim,

This 6 ohm value; does it have to be exact? I mean, what range can it be in: i.e. 5 - 7 ohm? Is it different for every bulb? Sorry about all these questions. I have access to a lot of different power resistors, cheaper than Jerry @ formymercedes. And I know that a lightbulb is not a simple resistor.

Guess this is just the 'sparky' in me asking about all the details and then some that I have forgotten.

vadim

I'd say - go with the highest resistance that won't trigger the 'burnt bulb" detection circuit. I would start with 10 Ohm and keep going down until the computer is satisfied. The higher the resistance, the less heat in the light cluster area.

Drew_ML

The load equalisers are specificially designed by the manufacturer of the LED bulbs to complement the bulbs and to dissipate the heat effectively. I would not recommend using some other sort of resistor to achieve the same results.

Surely if you can afford a Mercedes-Benz, you can afford the price of the load equalisers!

vadim

These load equalizers are nothing more than just 6 Ohm 50W resistors coupled with heat sinks. 6 Ohm is about what the stock bulb's resistance is, but it doesn't have to be exactly the same - it is only needed to fool the computer, nothing else. If, say, a 15 Ohm resistor would do the trick - use it by all means. Just make sure it is powerful enough, with Watt rating above ( 196/R ), where R = resistance in Ohms; 196=14*14 - square of the voltage supplied by the car's electrical system. 14 Volts is on a higher side, but it never hurts to have some room.

amdeutsch

I couldn't agree with you more Vadim.

Now if what Drew said
were to hold true than one wouldn't be able to get these as cheaply since a bulb is a complex electrical device represented by resistance, inductance, etc.
His other point
could bare some merit if the wattage rating would be ignored. Or if he were to get into the actual manufacturing of a resistor, thin film, wire wound, thick film, etc. But in this case I don't think he is fully aware of the actual design criteria that is involved in electrical components. Its just a salesman talking to him trying to push his product. For example and please don't flame me too hard here: HPS > sales/marketing monkey and not at all well versed in the technical aspects and/or implications of his product.


Drew

Now your other point
has been discussed in a lot of other threads.

I don't take your response as a flame the same as mine is not. We are all here on this forum to learn about our cars and capabilities; i.e. cost effective mods, etc. Why go with tires from the tirerack when you can buy the same from your stealer? Cost effectiveness is the answer. OK its a bad example but it holds true nevertheless. Or better yet. Why buy mods like wheels, springs, sways, etc. from a third party instead directly from the original manufacturer? Same answer. Get the most bang for your buck because you can get it below MSRP most of the time.

Drew_ML

Actually vadim, you have to be careful about that because the bulb out system seems to be very sensitive and you can easily blow a couple of fuses or not be able to trick the system into thinking that a regular incandescent bulb is there.

What I meant about using formymercedes' load equalisers was that one should not use a simple off the shelf resistor without the proper heat sink, etc as the unit gets quite hot after a short duration of the bulbs being illuminated. I've seen a few people solder in regular (tiny) 6 ohm resistors and the long term results were not too nice

lars

With the LED bulb output going mostly to the rear, it seems likely that less of the output is coming onto the lens off the reflector. Is there a hot-spot apparent inside the lens, Drew, or does the light appear evenly diffused across the whole surface? It's hard to tell from a CCD camera photo.

todd

Actually vadim, you have to be careful about that because the bulb out system seems to be very sensitive and you can easily blow a couple of fuses or not be able to trick the system into thinking that a regular incandescent bulb is there.

I have found it to be very sensitive. I currently have a bulb out indicated for the front right turn signal. This didn't start happening until I shorted the brake wear sensor but went away until it rained last week and I thought it would go off again, as the bulb is good, apparently to the eye anyway, and now it is stuck on.

Anyway, I still think it definitely would be possible to trick the computer with the proper off the shelf resistor and an old IC or CPU heat sink, maybe even a muffin fan to get really nerdy ;-) We use to install these are selves on CPUs way before anyone sold or OEMed such a device.

But on the other hand, like, I believe, the xenon setting in the computer, if I could get a copy of that star program, I could probably figure out a way to disable the bulb burnout sensing on each individually sensed bulb which would be a lot more efficient.

Bug, I digress, as I haven't gotten any responses to my inquiry about the Star program. *sigh* May just have to get employed there ;-)

vadim

Drew, fuses can only be blown if you install resistors of *lower* resistance than those "load equalizers", as that would increase the current - not the other way around.

vadim

Look up "star diag" in this forum - you should find lots of info on this topic. Even if it were possible to disable open circuit sensing (which I doubt), software alone won't do - you need a docking station with cables that connect to the car to operate it.