Electronic flasher for LED flashers

[ram100987]

I trying to replace all the bulbs in my 08 smart fortwo with LEDs. I've replaced a majority of them including the taillight/turn signal, reverse, and front parking bulbs. However If I try to replace the front turn signal with an LED they will flash very fast. Now in my other vehicle that I did this to I know that it's simply that the mechanical flasher relay needs to be replaced with an electrical one so that the smaller load does not effect the flashing speed. I cannot figure out where the flasher unit is on the smart though. From the research I have done it seems that the two relays next to the fuse box are what I am looking for, one for each side. They do not seem to be like a normal flasher though so I am a bit confused. Would I simply be able to run to oreilly's or some auto parts place and pickup two electronic relays or has smart decided to do some uncommon complicated flasher system? If I can simply replace those relays to allow for LEDs could someone please let me in on part numbers and where I can find them.

[SmartDigger]

This is a good ? I also would like to know this info.

If I read your post right, The rear bulbs do not produce hyper flash?

[ram100987]

Yes sir, my rear bulb are LEDs and it flashes at the factory rate, but if I try to replace the front turn signals bulbs with LEDs it will flash fast. I know on my old corvette the rear lights did not have an effect on the load on the flasher unit, only the front turn signal bulb. So I could be the same case on the smart.

[The Rigger]

Originally Posted by ram100987

Yes sir, my rear bulb are LEDs and it flashes at the factory rate, but if I try to replace the front turn signals bulbs with LEDs it will flash fast. I know on my old corvette the rear lights did not have an effect on the load on the flasher unit, only the front turn signal bulb. So I could be the same case on the smart.

What about if you put conventional bulbs in the rear and LEDs in the front. Does it work, or does it misfire? I'm betting the former...

You're correct in that the OEM flasher wants to see a certain load that having all LEDs doesn't provide. I think if you keep one bulb in each side conventional incandescent, you'll be safe. Maybe the side repeater would be enough of a load to allow you to replace the front & rear indicators with LEDs?

[LittoDeviL]

Originally Posted by The Rigger

What about if you put conventional bulbs in the rear and LEDs in the front. Does it work, or does it misfire? I'm betting the former...

Heh i couldn't help but think of an engine when you say misfire since led's don't misfire but I get what your saying ;) hehe

The other way to fix the issue which is going "backwards" in technology is put a 50 watt 8 ohm heatsink resistor parallel with the turn signal wires to let it draw the same amount of power. When I design high end custom headlights for my cilents I use this along with my led array. HS50 8R0 1%

I do have to say, replacing the brake lights with plug and play led's is not what I recommond, being someone in the lighting industry those led's don't put enough lumen to equal the amount of light coming out of the incadencent bulb your replacing, it'll take about 500 of those cheap 5mm led's or 30 of the superflux led to put out the same amount of light, this is not the same as the "intensity" of what you view when it's pointed into your eye.

Cheers,
Larry

[PerryA]

Originally Posted by LittoDeviL

. . . it'll take about 500 of those cheap 5mm led's or 30 of the superflux led to put out the same amount of light. . .

What about heat? I looked at LEDs and the auto parts store attendant offered a couple of comments on why I should leave well enough alone, and one was heat.

[John_H]

What aspect of heat concerns you? Incandescents are designed to generate (and work fine under) intense heat. LEDs will be much cooler than the bulb they repalce though some LEDs don't do well if on constantly in a confined space due to the limited heat they generate. Adding a load resister will return to the original amount of heat generated before the switch.

There are single LEDs that are 1W to 5W capable that have a much better tolerance to high temperature operation than what was available more than 2 years ago.

It doesn't take many 1W chips to provide the equivalent of a 20W incandecent.

[PerryA]

If I recall the conversation, the person at the parts store was talking about the housing. The local resistor would certainly help, but if you simply plug in a replacement, you haven't done anything to mitigate the potential heat generation-if the change would produce more heat.

For me it was merely curiosity that had me looking through the lighting section. It sounded plausible so I added that to the fact he was talking me out of a sale rather than into buying an unnecessary add-on or upgrade and so I stored it away for future reference. I defer to those with more knowledge and facts, but I wanted to add the question of heat because the answer has value for anyone looking at similar modifications.

[LittoDeviL]

Originally Posted by PerryA

What about heat? I looked at LEDs and the auto parts store attendant offered a couple of comments on why I should leave well enough alone, and one was heat.

Perry, John is correct, the LED's that are offered ESPECIALLY the cheap ones at the automotive store doesn't put out enough heat actually they are cool to the touch.

However, the led arrays I design require thermal management because led's do put out heat, the more light output you get, the more heat they generate especially if they are a close cluster. But there's nothing in the area of heat that you would have to worry about regarding the led's. They don't put out enough light to have much heat anyways. =P

The thing is the LED technology is just more efficent at using the power... so if you have a 8 watt led putting out the same power as a 27 watt turn signal when it's on, then that's great. However after a while the led's array will be putting out enough heat. That's why there's the term "thermal runaway" when designing led's. That's when they generate heat, and because of the heat they end up drawing more current.. and more current means more heat and.. it goes on and on until the emitter burns itself up. ;(

Cheers,
Larry

[PerryA]

Thanks. Love it when I learn something. I suspect the guy at the auto parts store was using the information he had on arrays and assuming it applied to replacement LEDs as well.

I hope this little sidetrack added to the original post.