nerdgineer
Flashlight Enthusiast
Or at least, not anytime soon. That is, Lambda's has run considerable lumen maintenance testing on his SMJLED PR bulbs (which I hadn't heard about until he just told me) where it has demonstrated very good to excellent lumen maintenance - so I thought I'd just pass this on...
I had been concerned because Chimo's original lumen maintenance tests of the parent MJLED running at 105 mA showed it started fading after about 24 hrs and hit 50% at about 60 hours. This is not awful but it's shorter than I'd prefer for a long run time light.
When I asked him, Lambda reminded me that the SMJLED PR bulb uses the 4 die SMJLED rather than the single die MJLED, so current through each die is much less and lumen maintenance is corrrespondingly better.
At 75 mA, Chimo showed the original MJLED had no measurable falloff at all in his life testing. The SMJLED bulb is (according to Lambda) spec'd to drive the LED at 80 mA so it's life at 20 mA per die should be excellent - it may even reach the thousands and thousands of hours we so often see advertised for LEDs.
In one test, Lambda ran the SMJLED bulb on 2 D cells for 168 hours, after which he re-tested it and found no loss of output at all. He has also run the MJLED at constant 100 mA current for days in his testing.
So, I'm thrilled to learn this. It removes my last concern about these GREAT little bulbs (and I am a worrier by profession).
I've come to view the SMJLED PR bulb in the 84 cent Wal Mart 2xAA light (faceted reflector version) as one of the hidden gems of flashlight-ism. In a PT Tec-20 or Sport Flare (same as Tec-20 plus nose cone, still available for $7 plus $7 shipping per order from here), it is the bulletproof, waterproof, etc. survival light version of same.
I had been concerned because Chimo's original lumen maintenance tests of the parent MJLED running at 105 mA showed it started fading after about 24 hrs and hit 50% at about 60 hours. This is not awful but it's shorter than I'd prefer for a long run time light.
When I asked him, Lambda reminded me that the SMJLED PR bulb uses the 4 die SMJLED rather than the single die MJLED, so current through each die is much less and lumen maintenance is corrrespondingly better.
At 75 mA, Chimo showed the original MJLED had no measurable falloff at all in his life testing. The SMJLED bulb is (according to Lambda) spec'd to drive the LED at 80 mA so it's life at 20 mA per die should be excellent - it may even reach the thousands and thousands of hours we so often see advertised for LEDs.
In one test, Lambda ran the SMJLED bulb on 2 D cells for 168 hours, after which he re-tested it and found no loss of output at all. He has also run the MJLED at constant 100 mA current for days in his testing.
So, I'm thrilled to learn this. It removes my last concern about these GREAT little bulbs (and I am a worrier by profession).
I've come to view the SMJLED PR bulb in the 84 cent Wal Mart 2xAA light (faceted reflector version) as one of the hidden gems of flashlight-ism. In a PT Tec-20 or Sport Flare (same as Tec-20 plus nose cone, still available for $7 plus $7 shipping per order from here), it is the bulletproof, waterproof, etc. survival light version of same.
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