Should be a good year for LEDs

[Tim Strommen]

This is not a post for any business, I just need to gush for a bit...

This press release came out this week from Philips Lumileds.

People who have been following this board may recall that I am a huge Lumileds fan - I insist on using their LEDs in all of my fixture modification projects.  This new "Luxeon S", is a 3000K (warm white) LED with a >80CRI (100 - daylight) meaning you can see a heck of a lot of the colors, unlike the cool, blue-ish LED with low <70CRI...  Amazingly it pops out 1300Lumens at just 18Watts!!!  This is about the same amount of light created by a new car's 35Watt High-Intensity-Discharge lamps (HID), and at about half the power draw (or about 1/4 the equivalent 65Watt Halogen bulb).

This LED requires a heat-sink as most of the >1Watt LEDs do...  Initial uses are to replace all incandescent bulbs in downlight fixture including the common MR-16 track light bulbs.  I can see these easily replacing fog lights and driving lights on cars in the near future in tiny physical packages, with follow-on retrofits for headlights...

How awesome is that?

Again, I'm not a paid spokesperson, not selling anything (although you can be darn sure I'm ordering samples!!) - just thought this was cool...

-Tim

[JohnEd]

Tim,

That is a great piece of info.  I am changing everything in my RV over to LEDs and that is a bunch of bulbs.  They are great and the "warm" 3000 items and 2600 are just as friendly to tread with as the old tungsten.

Thanks,

John

[Iceni John]

Wow!   At this rate there won't be any reason to use fluorescent or incandescent lamps at all inside our buses.   I plan on replacing all my smaller incan lamps with LEDs as soon as I can, if only for their increased life and reliability.   I'm curious how close LEDs are to being suitable for headlights  -  isn't Audi already offering this in Europe?   Maybe HID will end up being standard for headlights (notwithstanding DOT), and LED for everything else.

John

It looks like you and I are competing to see whose conversion will take longest to complete!   After two-plus years of sporadic work I'm still only halfway to completing all my under-floor support systems;  my interior is still only a distant dream.

[Tim Strommen]

…Wow!   At this rate there won't be any reason to use fluorescent or incandescent lamps at all inside our buses…

...Or houses, or businesses.  Fluorescents are one of the biggest environmentalist follies out there...  Sure they are more efficient than an incandescent bulb so less green-house gasses are produced POWERING them, but they have mercury in them to excite the phosphors and generate a ton of UV light (skin cancer anyone?), and when they are thrown out they require much more expensive handling than simple crushing and recycling than the old incandescent did, so you create more green-house gasses in production and disposal (kind of neutralizes much of the benefit).  Also, LEDs are easier to dim since you can turn them on and off >30,000 times per second at the same general cost as an always-on setup, and they are less prone to damage due to mishandling than both filament and arc-type lamps.

...I'm curious how close LEDs are to being suitable for headlights  -  isn't Audi already offering this in Europe?...

Audi is using another model LED from Philips Lumileds for the headlights (both high and low beam), and they are available here in the US too.  This new LED is by far more densely packaged that the other one.  The problem with this package is that it is huge... and complicated to create a light fixture for since the source format is a linear (1x4 or 1x2) row of LED emitters.  This new Luxeon S package is a simpler square (3x3) layout, I personally believe it won't be too long before we start seeing AFTERMARKET headlights (kind of like the Cibie H4 aftermarket stuff we always bring up on the forums), as oposed to OEM only like the Audis.

...It looks like you and I are competing to see whose conversion will take longest to complete!   After two-plus years of sporadic work I'm still only halfway to completing all my under-floor support systems;  my interior is still only a distant dream...

I got about four years into the conversion and decided to stop, and start over.  I was doing the hippy "just paint it and put a bed in it", but that didn't suit my flair.  Mine is now stripped back down to the frame and basic skin, but it's going to get cut just about down to the frame and heavily modified...  New suspension, new framing, raised floor and roof - but I'm 31 so I can bide my time .

-Tim

[gus]

I don't understand the heat sink requirement??

I thought LEDs are cool lights?

No other light requires heat sinks?

I agree that the fluorescent spiral bulbs are a joke, they don't last nearly as long as advertised. I had so many fail that I decided to buy no more.

[Jeremy]

I don't understand the heat sink requirement??

I thought LEDs are cool lights?

No other light requires heat sinks?

People think LEDs are cool because the ones they are familiar with are of very low power. Comparatively speaking LEDs actually produce a lot of heat - and there's another issue as well:- in a conventional lamp the heat production is spread out along a filament, which is itself surrounded by a large body of air - whereas with a LED the heat is produced at a very concentrated point at the rear of the fixture, which makes it difficult to dissipate . So heat management becomes a big issue with high-power LEDs

Jeremy

[Tim Strommen]

...I don't understand the heat sink requirement??...  ..No other light requires heat sinks?...

EDIT: I missed Jeremy's post - yes, what he said... -T

Most incandescent lamp fixtures have a heat sinking effect built into them by using air and stand-off distance - mainly they use open housings and rely on convection to keep nearby items cool.  If you put your hand a foot over a 60Watt filament lamp, you will feel a hot of heat rising off the bulb (I don't recommend touching one while it's runing 'cause you'll burn yourself it's so hot!!).  One other thing you might notice is that if you sit in the beam of an MR-16 halogen, you might feel a bit warmer when the light is turned on.  This is because the primary light output of a filament lamp is in the 1000nM - 1500nM range (thermal IR light). Only about 3-10% of the actual power consumed by the lamp is used to output "visible light".  It is the electrical heating of the filament that causes waste heat in form of the visible light which we use.  Also heat doesn't damage a filament bulb in the way that heat can damage an LED - the hotter the filament gets, the less power it passes, so it only gets so hot (we call this Positive Temperature Coefficient).

LEDs are different beasts... even on the small LEDs, you do heat sink them by having them mounted on a circuit board.  LEDs are more sensitive to heat because they are encased in a plastic or polymer case - and being silicon they are Negative Temperature Coefficient, meaning the hotter they get, the more power it passes (to it's own demise, often with spectacular effect).  Too high of a temperature at the die (what we call the part of the LED that produces the light), and it will melt and burn the plastic/polymer case directly in contact with the die.  This can turn the plastic brown causing it to block light passage, and make the LED appear dimmer.  Basically, you don't want heat to go out the front of the pastic case, and this is why LEDs use the positive and negative pins coming out of the package to get rid of most of the heat.  But note, with a 2.8Volt 25mA LED, that LED only consumes 0.07Watts which isn't very much.  You wouldn't try to heat a room with a 0.07Watt heater, you'd use something more like 1500Watts.  Also keep in mind that a 1500Watt heater creates heat over a very large area (1 square foot or more, so think 144square inches...).  An 18Watt LED is a totally different case than a 0.07Watt LED - and since these packages are more like a square inch than a square foot, the heat density is WAY higher.  The difference is "illuminating" (forgive the punn, I couldnt help myself ).

1500Watts / 144 square inches = 10.4167Watts per square inch
18Watts / 1 square inch = 18Watts per square inch (almost double the heater's density!!)

...I agree that the fluorescent spiral bulbs are a joke, they don't last nearly as long as advertised. I had so many fail that I decided to buy no more...

This can be a problem especially pops up in enclosed fixtures - many common CFLs are not designed for enclosed fixtures and actually require a lot of free-air convection to keep the electronics in the base cool.  There are CFLs that ARE rated for enclosed fixtures, usually you have to look for them...

-Tim

[gus]

Well, so far I've read nothing to convince me that LEDs are superior to halogen headlights when the higher cost is factored in. Eventually the price will probably come down, most electronic item prices usually do, so I'll wait this one out too.

Most headlights, even the old incandescent sealed beams , last for years. I own about six vehicles I use often and it is a rare event when a headlight needs to be replaced.

[bobofthenorth]

It was obvious at the recent Vancouver Boat Show that there is FINALLY starting to be some real competition in the 12 volt LED market.  My Rube Goldberg LED fixtures are still working just fine in the bus, thank you very much, but for the re-light project on the boat I am aiming for a little more up-market appearance.  So it has been very frustrating to not see any real competition in that market space but that appears to be changing.