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  1. #1
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    Battery options for DIY lights

    I was just looking into options for batteries for my light project (3xCree XR-E driven by Fatman) and saw that you can get replacement camcorder batteries for fairly low prices. These are 7.2V Li-Ion packs that are about 1.5"x2.25"x2.5" and capacities from 3000mAh to 4900mAh. Any reason why I shouldn't consider them? I'm not up to speed on the Li-Ion batteries and their potential problems, so I guess the question is would these packs have issues with high current draw applications (750-1000mA). If not, then I think they'd make an ideal setup for a DIY battery...

  2. #2
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    It may depend on the specific battery but overall, I tend to think you'd be fine. The LCD displays and motors used in video cameras are fairly high drain devices as well. If you go this route, please share your experience.

  3. #3
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    I've got a dead camera that I've ripped the mount out of, so I may just "test" an older battery to see if it burns up or something. My LED kit is on its way (next week some time) and I haven't made the housing yet, but I'll definitely post some info if/when I get something working. I guess my biggest worry is destroying stuff. I don't really want a Li-Ion fireball while bombing down the trail...

  4. #4
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    I am thinking about the same kit (Cutter mr-11?) for a Marwi housing. The Marwi light is a 12v 12watt. The open question is fatman vs. bflex or the new driver which I think is a fatman/blfex "hybrid". Any suggestions? I will be using the Marwi battery for now.

  5. #5
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    Bear,
    If you're running a 12V battery, you may be in a bit of a dilemma. The Fatman is a boost driver, meaning that it needs less voltage than the Vf of the LEDs. In the case of the Cutter kit, that's approx. 11.1V. The bFlex driver is a buck driver, and needs 1.5V MORE than the Vf, which puts you at 12.6V. The Fatman will work with any voltage from 2.7V up to the Vf of the LEDs, but if you supply more than the Vf, the voltage will basically bypass the driver and go straight to the LEDs, losing the current control.

    HTH

  6. #6
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    It sounds like the bFlex is the way to go?

    I need an electronics for dummies book... :-)

  7. #7
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    Looking at TaskLED's site, yes. It says that the bFlex v2 only needs 1V more than the Vf (forward voltage) of the LEDs. So in your case that's probably the best option. I'm using a 7.2V or 8.4V battery for mine, so the Fatman is the one I needed.

  8. #8
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    Thanks for the info, time to order a kit!

    Electronics for Dummies - I should have known there would be one :-)

    http://www.dummies.com/WileyCDA/Dumm...764576607.html

  9. #9
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    Quote Originally Posted by dnlwthrn
    Looking at TaskLED's site, yes. It says that the bFlex v2 only needs 1V more than the Vf (forward voltage) of the LEDs. So in your case that's probably the best option. I'm using a 7.2V or 8.4V battery for mine, so the Fatman is the one I needed.
    No, it's not.

    When his batteries are depleting, the total battery voltage (-1V for the bFlex additionally) goes below the Vf of the LEDs, thus going into direct drive.
    The bFlex cant keep the LEDs in regulation for the full duration of his accupack.

    A buck-boost driver would be best here.

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