Nichia GS direct drive discharge graph?

Buck91

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Well, while considering throwing together an ultra mini-BOB, I came up with a question that, with any luck, somebody on the boards here has an answer to.

What would the output discharge graph look like of a GS led directly driven off two normal AA batts (and/or two lithium AA batts)? I have one I dropped in a minimag light, and while not terribly bright its comparable to my fauxtons. Besides the alkaline voltage drop of curve, my DMM readings with fresh batts are nonsensical making even just a baseline difficult (0.7vdc @ 10mA
wtf.gif
).
 

Jarl

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IIRC, 2 fresh alkie AA's in a MM with a GS draws 10ma. HTH.
 
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Buck91

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No kidding? Well, still doesn't explain the .7vdc, but I've seem my DMM do that before.

So, at 10ma draw, figure a good 20-30hrs until half; anyone disagree?
 

jupello

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Yeah, at least those 30 hours.. if the current is only 10mA, the runtime could be a lot more too.. with 1700+ mAh in the alkaline it should run for 170+ hours in theory, if the voltage does not drop too much. But since the led most likely would like to get little ligher voltage from the start than the 3- volts, it could be that it refuses to light up when the batteries are half-used or something, if the voltage have dropped too much.

I'm just making guesses, but surely someone has experience from this? :)
I only have some common white 3.5mm led in my minimag and no experience from the runtime since it's not used much.. :whistle:
 

Buck91

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I know the GS doesn't mind a slightly lower vf, but thats my concern too, that it will fail to light up when the batt's are only partially used. I have considered throwing L91's in, but at that point I might as well just use my SMJLED minimag.
 

Buck91

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Just bringing this to the top to see if anyone knows of a proper runtime test... I could do an ad hoc, but would much rather somebody with the proper equipment provide real numbers.
 
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