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Thread: Remora problem?

  1. #1
    Flashaholic* Techjunkie's Avatar
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    Shrug Remora problem?

    Just tested the three blue sharks I ordered from the shoppe and they all passed. I measured 970mA from a single IMR 16340 (4.2V in) delivered to an MC-E emitter wired as 2s2p (7.2Vf). The same battery in direct drive would not even light the 2s2p config. The sharks had the pots removed and no pads bridged.

    After adding the Remora to one of them, the same test yielded 110mA on low, ~340mA on medium (I forget the exact measurement) and only 840mA on high. Where'd my 970mA go?

    I tesed with a 7.2v 6xAAA battery carrier that drives the same 2p2s at > 1.5A and still the shark with Remora only delivered 840mA to the emitter. I also noted in this configuration that Low and Med. modes both pushed 760mA to the emitter. What happened to my nice low and med. modes when Vin was almost = Vout?

    Is my Remora not functioning properly, or is all the above the expected behavior?

    (I have since removed the Remora and un-bridged the 2 pads again to return to single/high mode 970mA output. Simply disconnecting the Remora V+, but leaving the pad bridged and the Remora PWM and Gnd. connected yielded a single mode 920mA output.)

  2. #2
    Flashaholic* LED Zeppelin's Avatar
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    Default Re: Remora problem?

    I've also noticed a drop in max current when a Remora is wired. I don't know why, but I would consider it typical. The numerical difference is much more than the perceptible anyway.

    For lo and med modes to regulate properly Vin must be below Vf at those drive currents. If Vin is near Vf on hi, then lo and med will be direct drive since the Shark is boost only.

  3. #3
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    Default Re: Remora problem?

    Quote Originally Posted by LED Zeppelin View Post
    If Vin is near Vf on hi, then lo and med will be direct drive since the Shark is boost only.
    I suspected as much. I had hoped that the Remora behavior would be like PWM dimming, where a PWM turns power to the LED on and off very rapidly to give the appearance of dimming when on a low duty cycle. Apparently that's not the case with the Remora where the PWM regulates the boost circuit activity, not the final output itself.

    Quote Originally Posted by LED Zeppelin View Post
    I've also noticed a drop in max current when a Remora is wired. I don't know why, but I would consider it typical. The numerical difference is much more than the perceptible anyway.
    Having seen what my XX-Ray torch performs like at only 1.54A draw (DD mode), I suppose I would still be very pleased with 2.52A on high instead of 2.92A single mode.

    I've got plenty of time to rethink the Remora decision now that I've completely fried all three blue sharks. I accidentally reveresed input polarity and bye bye money. I really don't have the pockets for this and this was to be my last hoorah. I'm pretty bummed about my grand finale ending in disaster.

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