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Thread: HBFlex help..

  1. #1
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    HBFlex help..

    Hi all
    Not been on here for a while but after some help with an issue with my light set-up.

    HBFlex running a 4up XPL-Hi (in series) from a 7.4v3.6aH battery.
    After a couple of minutes the LED's flash then the light turns off.

    Any ideas?

    Thanks
    Steve

  2. #2
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    Quote Originally Posted by deesta View Post
    Hi all
    Not been on here for a while but after some help with an issue with my light set-up.

    HBFlex running a 4up XPL-Hi (in series) from a 7.4v3.6aH battery.
    After a couple of minutes the LED's flash then the light turns off.

    Any ideas?

    Thanks
    Steve
    I would say that means the battery voltage dropped below v.cut which defaults to 6V I believe. If you aren't using high quality batteries the voltage could be sagging significantly under load. In my experience LiPo batteries are usually the best solution to avoid this problem.

  3. #3
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    For starters, the HBflex is 7V minimum input voltage. George says it may do OK as low as 6.5V but no guarantees.

    Another thing that can cause the hbflex to register low battery voltage is trying to pull too much current through small wires. Boost drivers like the hbflex are tough on batteries. For a 4S XPL light I would not try to use anything smaller than a 4 cell battery in 7.4V configuration (2S2P). IMHO you'd be better served with an 11.1V 3 or 6 cell battery. The light will be more efficient and draw less current from the battery. Potential drawback might be that with the battery fresh off the charger your lower modes might not work as the light will be at or very near direct drive.
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

  4. #4
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    Thanks both.
    Would there be a better led to use with this setup?
    I like the small battery as I don't use a backpack and the battery straps to my helmet.
    I need to get some new LED's as I've toasted these plugging the wrong battery in..
    It's a helmet light so after good throw.
    Thanks
    Steve

  5. #5
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    The XPL-HI is the an excellent emitter for throw, particularly when used with optics or reflectors in the 20mm or so size. IME, the best I've used.

    What current level do you run them at? If you are driving them at high current (3A or so) then that is a tall order for any small battery to provide that much power. Even if you go to a LiPo (RC) battery that can deliver high current, it won't last long. The 7.4V 3.6Ah battery that you are trying to use would only power the light for ~30 minutes at best if your drive current is 3A and the pack able to provide that for long.

    If it were me, I'd stay with the XPL-HI emitters and wire them 2S2P then switch drivers to a B3flex and run it at 3A. Each emitter will see 1.5A and 4 of them will make plenty of light. You'll get about an hour runtime from your battery. If you really want to run max current, then an H6flex could do 3A to each emitter in the 2S2P configuration. Your battery may support that for a bit but I think you'll still have trouble with voltage sag trying to draw that much power from a 2 cell pack.
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

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    If you wired your array to 2S2P, you could also do a 6V modded QLite linear driver with your 2S battery - and add 8 7135 chips to increase the current to ~6A. You'd lose some features - especially Lo Voltage turn off, so protected cells would be recommended. QLITE 6V+ Zener Mod - For 6V MT-G2/XHP

    But the guppydrv UI would give you a lot of modes and output levels to work with. At least that way you could get to full output if you reallllly needed it, but could normally run around at 50% power for battery life.

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