3W powerled

[Simen]

For the last couple of months, i've been testing some led lamps with a single 3W (12V) led, and i'm surprised at the performance of these lamps.

I've dissected one lamp, and put some photos here:

http://www.mwlmf.net/gallery/3W_Diodelamp

The specs for the lamp are: 3W, 11-17V, 60 lumens, 36deg. spread, 3000k colortemp, 10k-30k lifetime.

It seems that the electronics inside the lamp limits current, because i can not see any difference in light output at 11V vs 17V. Also, they does not dim after a while, like standard diodes does with a little overvoltage.

I've tested several other led lamps with 18-21 leds in each lamps, and the usually dims considerably after some months. (Seems that they doesn't handle the charging voltage for my batteries...)

A side-by-side comparisation of these 3W lamps with a similar 20W halogenlamp, there is little difference in light output; the 20W are a little brighter, but not by much.

The downside is price...

Around $24 here in Norway...

[jimovonz]

I recently ordered some of the Luxeon Rebel LEDs. Specs show 180 lumens of cool white light from a single component (under 3W) with a 50kH lifetime.  (over 200 lumens continuous at 1A with reduced lifetime). Cost approx $US8. There is also the Star Tri-Emitter capable of around 700 lumens (~10W)

[independent]

I've installed some nice 1w LEDs which came from a man in China. He also sells HV rectifiers and other esoteric bits and pieces (on that auction site). I got them with a ballast and made up some lights for my bus. They work well. The colour is very neutral, not cold. I like them 1w, 50lm but he also has 1w 60lm. With all 10 LEDs on (2x ballasts) they light up the whole bus very nicely (this is with a diffusor to soften the light).

With 5x on 24-30v ballast I am getting 6w for all including the ballast. Works out as spec with 1w each including the ballast. I was pleasantly surprised with these no name LEDs. Especially with the colour. For the price they are 10x better than anything you can buy retail and very efficient.

I'd have to say they are more efficient than the fluoros I have.

[richhagen]

20 lumens per watt is not that great by todays standards though.  Cree, among other manufacturers, is currently shipping cool white LED's with outputs of 107 Lumens per Watt at 350 mW by comparison.  This becomes inportant if you are running off of limited battery power.  The efficiencies of LED's have been steadily increasing in terms of the light output per Watt.  You can efficiently drive them with a simple 555 based pwm driver circuit the design of which is readily available online, or build a very robust constant current circuit such as the one Commanda posted on this site and still achieve reasonable efficiencies.

I made a batch of LED lights for a project last year with Cree LED's and Commanda's circuit and was very satisfied with the results.  As of the last report I had the ones we mounted are still performing well in a marine environment.  I have more recently made some with the 555 based pwm circuit, which are more efficient, and dimmable, although likely not as robust as the ones with Commanda's circuit.  Rich

[dnix71]

Heat is the killer for LEDs. In the shop were I work we have literally thousands of 4 foot fluorescent (T8 and T12) tubes, as well as a couple hundred 8 foot fluorescent tubes and a bunch of halogen high hats.

The ceiling in the shop and warehouse is 2 stories high, unfortunately. Even if we could afford the T8 LED replacements, they would melt in the summer. The area in sales, creative and corporate with standard drop ceilings would be the only place where the teperature is kept controlled well enough to get the rated life on LEDs.

Just before Christmas we got a letter from the county waste management tellings us not to put compact fluorescents in the trash. We are supposed to get in line on a weekend at one of the 3 official hazardous disposal facilities. Thats such a stupid rule that they have to know it won't happen (I live in Broward County Florida). The letter also said to evacuate the home and call hazmat if you break one.

The only way I see to make everyone happy is if LEDs get cheap enough for the average person and compact fluorescents and simply banned because of the mercury in them.

[dnix71]

'compact flourescents are simply banned for the mercury in them.'

[Simen]

Yes, when serching a bit i see that cold white leds are easily available in the 100+ lumens range, but only a few warm/neutral white.

I guess it's a matter of taste, but i really hate that cold white light... :-o (Maybe a result of living above 58N; one really appreciates the warm light of summer more... )

Anyway, the good thing is that there's now increasingly better availability of led-lamps that are actually useable replacements for standard low-voltage lightbulbs. (I'm currently using an average of 25Ah/day (12V) for lights in my livingroom and kitchen. (Sun rises at 9am and sets at 3pm midwinter here in southern Norway.)

[Tritium]

A neat trick is to add some red 3 watt as well as the cool white. Maximum lumens and down shifted apparent spectrum as well.

Thurmond

[independent]

I was hinting at that efficiency too. The thing is Q5 (100lm/w)) and higher rated Cree and Lumiled LEDs is that they are expensive. I have bought some warm white (the highest rated warm white at the time 87lm/w) Cree's and the best price I could find was nearly $US15 each or so..

So, there is a trade off between efficiency and cost and that's why I mentioned these generic 1w LEDs. From memory they weren't much more than $US1 or 2 dollars each.

Here is the guys store, http://stores.ebay.com/OT-Electronics , I have no affiliation with him or with his products. The price seems to have gone up and so I don't know how they compare these days with other generic products.

He has other stuff building things like Tesla coils if anyone is interested.