cree, philips, piaa... anyone tried them?

[paulg23]

Been looking at LED headlights. Usual mix of useful info and bullsh*t on t'internet. Any one have any first hand experience?

[Davezj]

i have used cree leds they are really good.

when you fit them, if they don't work take it out flip it round to reverse the polarity and put it back in. LED's have a pos and neg side.

[Grid]

Dave, Cree LEDs are good, but not for the headlamps. There are several unsolved issues in most LED bulb replacements. First thing is heat - large power LEDs heat up a lot, they heat up more than classic bulbs and that heat has to be disspiated. If it is not dissipated it will kill the LEDs very quickly. Second is the directionality - it takes a lot of engineering to make a LED shine in all directions like a normal bulb does. Basically for a decent LED headlight you need a reflectorless headlight design like some Audis have.

Xenon projectors are a better bet IMO, I would stay clear from LED headlamp replacements.

[Davezj]

Dave, Cree LEDs are good, but not for the headlamps. There are several unsolved issues in most LED bulb replacements. First thing is heat - large power LEDs heat up a lot, they heat up more than classic bulbs and that heat has to be disspiated. If it is not dissipated it will kill the LEDs very quickly. Second is the directionality - it takes a lot of engineering to make a LED shine in all directions like a normal bulb does. Basically for a decent LED headlight you need a reflectorless headlight design like some Audis have.

Xenon projectors are a better bet IMO, I would stay clear from LED headlamp replacements.

I had assumed when taking about LEDs and headlights it was the sidelight/driving light/daylight running light bulbs he was talking about.
Cree LEDs are are great for those, not actual headlight bulbs at the current led technology state. I have some led headlight bulbs and they are not powerful enough to light anything up, but they were only cheap versions.

By the way LEDs do not create more heat than conventional bulb for a given lumin output. That is why they were invented they are much more efficient than filament bulbs. They give out much more light per watt of power consumed than any filament bulb.
I have some 5w Cree led bulbs in my kitchen and they give out more light and less heat than the 35w bulbs they replace.

[Nick Mann]

Dave, I don't know all the facts but led lights do produce a lot of heat. The difference you notice is due to the filament light producing a lot of infra red which heats things up when it hits them. So a filament light will heat up its lens, it's fitting, even the surface a foot away that it is pointed at. Leds don't produce infra red so they don't do that.
I can't remember the numbers, but the majority of the power for a filament light is infra red, followed by heat and then visible light at (from memory) around 5%. Leds provide much more visible light, (again from memory) around 20% of the power is converted but the rest is pure heat. That heat must be conducted or convected away otherwise the led will overheat and significantly reduce its lifetime. Check out your gu10 led replacement and it will have a combination of holes, flutes and fins to get rid of the heat.

[Davezj]

That is not the point the laws of conservation of energy.
Energy can not be created it can only be coverted.
The same amount of energy into a system will come out of system in one way or another.
With respect to filament bulbs the 35w bulb will produce light and heat, say 500 lumins of light.
If a 5w led bulb produces the same 500 lumins of light then the led bulb has to produce less heat.

Yes I agree the led bulbs have to be cooled but they do not have to get rid of more heat than a filament bulb. They have to get Rid of it in a different way.
The heat from an led is very localised so is more difficult to remove. So when I am design circuit boards at work if they are led boards then I have to consider using a metal backed PCB to remove the heat so I do understand heat sinking requirements of LEDs.

[Nick Mann]

I think the problem in this argument is with the term heat. If you separate infra red from the term heat then an led bulb produces more heat. I'd have to Google it, but from memory a filament will convert 5% to visible light, 75% to infra red and 20% to heat. An led is more like 20% light 80% heat. So depending on how you classify the heat depends on how you view the hot led argument.

[Amonlym]

To chime in on what is becoming a good read with mostly valid points:

Both bulbs dissipate heat.
LED's generate far less heat per unit of useful light - they are more efficient, less power is drawn from the 12V system to achieve the same lighting function.
Conventional bulbs reach very high temperatures and thus can radiate away their waste heat as infra-red light, with some conduction and convection.
LED's cannot tolerate high temperatures, so they cannot radiate a lot of the waste heat as infra-red, as a result it has to be conducted or convected away (hence for household bulbs they are heavy with a lot of metal heat sinking).
your headlamp fixtures were not designed for conducting or convecting heat from the bulb (plastic bulb holder, bulb held proud inside an enclosed air-space).

because of the above:
Retrofit LED's unless very well designed and exceptionally efficient will tend to overheat, or under perform without changes to the fixture design in some situations (no enclosed down lighters at home for example without the fan assisted designs).

as a bonus:
Retrofit headlights tend to (not always - but do get them checked by a good garage!) give a bad (for you, or other motorists) light pattern because the light is no longer emitted from the near point source of the filament in the standardised shaped bulb it was designed for.
IMHO - try and borrow a single bulb, fit it and take it to a local garage to check the beam pattern, if that is ok switch it on for say 30 min, then check if it got dimmer or if the bulb itself got much over, say, 80c.

[Davezj]

You should not have an issue with the sidelight bulbs as these are low light output anyway. The standard sidelight bulb is only 5w so a 1w led replacement will not have any issues.

Here is a little info on the subject of headlights I will share with you. If you use a 100w headlight bulb in the standard vr4 headlight it will burn up the connection converter socket that the bulb plugs into. I know this from personal experience.

[billybobboot]

Led headlights produce a very bright light with low head, the only issues with led headlights is once the bulbs start to blow they pretty much all start to go. You then have the issue you cant easly just change 1 bulb, the only other thing ive had with led bulbs is the not a very wide spread light there still very direct what you point at is what lights up type of thing.
Mot wise your fine as long as they produce a white light and give out the correct strengths of light. And as long as 50% of the light is working. A word of warning if the lights give out to little effort it will also fail.