Re: UPDATE LED Life Test at 2 Months

From: Watson A.Name \ (NOSPAM_at_dslextreme.com)
Date: 07/07/04 

Date: Wed, 07 Jul 2004 07:22:07 -0700

Kevin McMurtrie wrote:

> In article <10ejul0jvd4ok4c@corp.supernews.com>,
> "Watson A.Name - \"Watt Sun, the Dark Remover\""
> <NOSPAM@dslextreme.com> wrote:

>>I I've had the 4 LEDs operating at 25 mA for all of May and June, and
>>the first few days of July. This is about 1500 hours so far. The LEDs
>>are two Nichia NSPW500BS white LEDs, and two white LEDs from Hong Kong
>>that I got off Ebay. All four are in series so there is no doubt that
>>they are all running at exactly the same current.

>>The two Nichias are going strong, with no noticeable signs of dimming.
>>The two Hong Kong LEDs, sad to say, are so dim that they wouldn't make
>>good panel lights, so can't even consider them suitable for
>>illumination. They're really quite dim.

>>Of the hundred Hong Kong LEDs I bought, all I've used have had this
>>dimming problem after a few hundredds of hours, so I decided to put the
>>four on a PS to control the conditions and verify that I'm not imagining
>>things. I think one problem might be that the Hong Kong LEDs use an
>>organic phosphor that degrades faster than Nichia's, and might
>>contaminate the LED chip. But I'm not an expert on this at all, so I'm
>>open to any other ideas.

>>I posted an update of the progress of the dimming at the beginning of
>>last month, and now this one shows that the hong kong LEDs are so dim
>>that it's probably not worth continuing the test. I may solder two more
>>unused hong kong LEDs into the circuit, and start the test again, just
>>for the halibut.

> I've had problems with several white LEDs from Fry's Electronics failing
> too. They dimmed after a few months of use then they started blinking.
> It sucks because some are inside a night hiking flashlight to keep it
> glowing while switched off. It's hand crafted inside a tough acrylic
> tube like a ship in a bottle. The LEDs can't be removed. I didn't
> think I'd need to make LEDs replacable.

> I'm going back to green LEDs for the next flashlight.

What color are they? I bought some cheap blue LEDs, and they were just
like that atraight out of the package. After five minutes on the PS,
they started to get erratic.

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