How well do underdriven Luxeons work?

paulr

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I mean if you power a Luxeon at waaay under the rated current, let's say 70 mA or so. Does the color change much? How is the efficiency of a high flux Luxeon at that current, compared with a high class 5mm Nichia?

I'm wondering whether a Luxeon would be a good alterative to a 5mm LED in a low powered light, since Luxeons seem to have much smoother color these days, and you don't have to worry that they're getting overdriven at 50-100 mA.
 

PhotonBoy

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My impression is that the efficiency improves immensely. I think Arc's new LS4? model will do well since it will be able to sip power on demand.

For short distances, using a tail cap in a small light with low output power, Luxeons will prove to be highly useful and long-lived. High power bursts will be available too. Arc is on a good path.
 

vcal

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[ QUOTE ]
paulr said:
I mean if you power a Luxeon at waaay under the rated current, let's say 70 mA or so. Does the color change much? How is the efficiency of a high flux Luxeon at that current, compared with a high class 5mm Nichia?

I'm wondering whether a Luxeon would be a good alterative to a 5mm LED in a low powered light, since Luxeons seem to have much smoother color these days, and you don't have to worry that they're getting overdriven at 50-100 mA.

[/ QUOTE ]
I've powered up both my White and Royal Blue Luxeon 1W units on as little as 5mA. -No color change either.
 

georges80

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Colour will still be fine - PWM is the correct way to dim and retain a constant colour temp, but I've driven Luxeons down to around 10mA and they still are white enough. I run them that low for nightlight mode - you can still read with a Luxeon running at 10mA (once your eyes are night adjusted). The nice thing with the Luxeon is you still get a nice wide beam (depending on your optics), while a 5mm LED has a 'narrow' beam. At 70mA you will get a LOT of light - MORE than enough to read with. I'm pretty sure you'll have a lot more light coming out of a Luxeon underdriven at 70mA than a nichia or two driven to 70mA.

I run my 1W Luxeons from about 10mA through to rated current on my adjustable driver and it is a GREAT feature for a reading light. Extends battery time enormously and still provides plenty of good wide angle reading light.

george.
 

Chop

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I've gone through about a dozen Q3J's when I was first getting into modding. You know, dinging them with the soldering iron, etc. They still worked, but didn't want to put them into flashlights. I took them and re vamped all of the tap lights I had in the house. I used 20 ohms of resistance and drove them with 4XAA's. If I remember correctly I'm driving them at around 150mA. The color of the light is nice and white. Great for reading and the batteries last forever.
 

LED_ASAP

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I've taken an Arc AAA circuit and used it to drive a Q2J HD. It's driven at 40mA and the color and brightness is waaaaay better than the stock 5mm Nichia.
 

McGizmo

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Another advantage I haven't seen mentioned is the lack of thermal build up when the Luxeon is underdriven. The Arc AAA mod that I did with one of ArcMania's MC's I think is putting out around 150 mA to the LED and after 5 minutes, the little Arc is just noticibly warm. In other words, Cool!

- Don
 
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