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How do you get 220 lumens on a 800ma draw?

  • sic22 Thursday, January 1, 2009 1:22 PM Reply
    @0,8A Cree Q5 produces 205lm, these from newest batches even more. I think 150-180 out of the front lumens is possible. Of course current draw from the battery will be high (~2,5-3A from Ni-MH) and it will heat up quickly.
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  • MerkurMan Thursday, May 28, 2009 6:32 AM Reply
    Very easy...by drawing 2A from a NiMH! I measured the draw on my A10, and that's what it pulls from a fresh Eneloop. It's about on-par with my Nitecore D10 R2 running on 14500 when it comes to brightness as well. No saying how long it'll last pulling that kind of juice...
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  • James_C Tuesday, July 28, 2009 12:25 AM Reply
    If it actually draws 2.0A from the battery, it can't produce 800mA drive current because that input power, minus some inefficiency of the driver (often about 15%), is less than the output power needed to drive a XR-E at 800mA.

    However, we don't necessarily want so high as 800mA drive current on anything this small unless the flashlight will only be used for short periods (less than 10 minutes at a time). A flashlight this size with 800mA drive current, no matter how well or poorly heatsunk since heat will build up inside even if not heatsunk to the body well over several minutes, would get too hot to comfortably hold.

    The ideal drive current for max brightness flashlights is just below what the body can radiate before getting hot, meaning that if max brightness is important and it's a hand-held flashlight, best to get something proportionally larger.

    Then there's the other factor, to avoid substantial voltage droop during continuous running you wouldn't want battery discharge of a single AA much below 1C either.

    This light seems to strike a good balance, the only reasonable way to get a brighter flashlight is one with higher binned LED than Q5, larger, or using Li-Ion which it supposedly can do (I've not tried Li-Ion in it).
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  • fluke Wednesday, July 29, 2009 6:48 AM Reply
    220 lumens ???
    Mine is more like 80 on a lithium primary, one of the weakest flashlights I have, even my old MTE P4 is better.
    And being in the UK it is too much hassle to sort out.
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  • James_C Monday, August 3, 2009 2:55 PM Reply
    fluke, check the contacts in yours as you should be seeing better performance than that. Measure current consumption too, if it's being underdriven from bad electrical connection you should see this as lower than expected current.

    If you can get the driver pill out you might try holding the battery contact to it, and holding a jumper wire from bottom of battery to the other driver contact and compare that brightness (and remeasure current).
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  • DDN84 Friday, August 14, 2009 4:44 AM Reply
    Mine draws ~1.2A on 1x eneloop (around 80% full) and ~1.7-2.25A (starts off @1.7 then increases quickly) on 1x TF 14500 (open voltage of 3.92V). I don't know if the current draw is still accurate when I connected my multimeter but if it's actually 2.2A then that's crazy, I doubt the switch can actually sustain such current for long period of time.

    I did some ceiling bounce tests; When running off 1x Eneloop, it's actually brighter than my P3D 5C-Q3 modded on Hi (~105 LED lumens) and with 14500, it's brighter than my Quark AA 5A-Q3 on Max (also on 14500, ~140 OTF lumens). My guesstimates for UF A10 are 100 OTF lumens on 1x NiMH and 160+ OTF lumens on 1x 14500.

    Anyone got a runtime test on 14500? After seeing such extreme current draw with my multimeter, I'm scared to use my TF14500. Not only the current is too high for the battery to handle, it's only a matter of time before the switch dies if it lets ~2.2A continuously pass through.

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