Need help planning DIY Light- Mtbr.com
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  1. #1
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    Need help planning DIY Light

    I'm hoping to power either 2 Cree XR-E's or 2 Seoul SSC P4's.

    The battery I was thinking of was a Li-Ion pack thats 7.4V and 2000mAh

    I'm guessing that's not enough voltage to use with a bFlex if my understanding is correct?

    What if I used a power puck. Would there be any big draw backs except picking the current I want to run with and not having any modes?

    About how much runtime do you think there would be?

    Thanks
    www.mtbiker.ca

    My Rides:
    FSR XC -R7 Platinum - SRAM X7 (26.5lbs)
    Cervelo SLC - SRAM Rival - Reynolds DV46T (16.25 lbs)

  2. #2
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    hmmmm

    2 p4s will have about 7.4v drop at 1 amp. I estimate run time at about 1.5hours for 1A on that battery or 2.4 at 0.7A for this I would say you need a combined buck/boost if you are set on that battery. or settle for dimming later in the run.

    if it were me I would go up in bat voltage and keep the nflex. if you raise bat V you can proportionally lower capacity to get the same run time and similar battery weight. the puck will be cheaper and you should get constant brightness.

    the nflex has low voltage warning too...so your lithium battery doesn't get over discharged.

    I would want longer burn time though personally, so I would keep the capacity higher.

    Stu
    Last edited by Stuart B; 05-05-2007 at 06:29 AM. Reason: thought of something else
    What exactly is a rigid hard tail?

  3. #3
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    Thanks Stu,

    I was thinking of using that battery because those are the specs for the Canon SLR camera battery me and a few friends already have, and this would be sooo convenient. None of us do any serious trail riding at night and are looking for just over an hour of run time.

    We might have to go with an 11.1V 2000mAh battery on Batteryspace with a charger that's cheap as dirt!
    www.mtbiker.ca

    My Rides:
    FSR XC -R7 Platinum - SRAM X7 (26.5lbs)
    Cervelo SLC - SRAM Rival - Reynolds DV46T (16.25 lbs)

  4. #4
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    Quote Originally Posted by bbgobie
    Thanks Stu,

    I was thinking of using that battery because those are the specs for the Canon SLR camera battery me and a few friends already have, and this would be sooo convenient. None of us do any serious trail riding at night and are looking for just over an hour of run time.

    We might have to go with an 11.1V 2000mAh battery on Batteryspace with a charger that's cheap as dirt!
    in that case...you could run a puck for each led. this allows safe independent swiching and givesthe required voltage headroom.

    Stu
    What exactly is a rigid hard tail?

  5. #5
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    Quote Originally Posted by Stuart B
    in that case...you could run a puck for each led. this allows safe independent swiching and givesthe required voltage headroom.

    Stu
    That might be a good option, and keep the costs way down.
    www.mtbiker.ca

    My Rides:
    FSR XC -R7 Platinum - SRAM X7 (26.5lbs)
    Cervelo SLC - SRAM Rival - Reynolds DV46T (16.25 lbs)

  6. #6
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    yeah. system effiency is about the same too.

    it should make a nice light.

    post it up when you are/have doing/done it.

    what are doing housing wise?

    Stu
    What exactly is a rigid hard tail?

  7. #7
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    Quote Originally Posted by Stuart B
    yeah. system effiency is about the same too.

    it should make a nice light.

    post it up when you are/have doing/done it.

    what are doing housing wise?

    Stu
    I was leaning towards a Hammond Aluminum project box. A bit more than the square tubing, but I always like these little boxes.

    For me, its honestly more of a commuter light than anything. I might just end up sticking a Cree in a few inches of tubing and mounting it to my bike as that would be enough.

    I like to mess around with things, but the costs of this light are going up faster than I thought it would
    www.mtbiker.ca

    My Rides:
    FSR XC -R7 Platinum - SRAM X7 (26.5lbs)
    Cervelo SLC - SRAM Rival - Reynolds DV46T (16.25 lbs)

  8. #8
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    DO you guys think a 9.6V NiMH Battery has enough juice to power the 2 Crees + a bFlex?
    www.mtbiker.ca

    My Rides:
    FSR XC -R7 Platinum - SRAM X7 (26.5lbs)
    Cervelo SLC - SRAM Rival - Reynolds DV46T (16.25 lbs)

  9. #9
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    looking at the datasheet for the bflex I would say yes...just. It needs 1.1V overhead of the Led Vfs which means about 8.5V battery voltage before it drops out of regulation mode. Which is probaly about what that pack is at end of charge.

    Stu
    What exactly is a rigid hard tail?

  10. #10
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    Thanks Stuart,
    you've been most helpful, and most importantly I may have found a power source that will help keep costs down and put it in to a budget where I don't feel like I'm blowing a lot of money just coz I wanna play with some bright new LED's!
    www.mtbiker.ca

    My Rides:
    FSR XC -R7 Platinum - SRAM X7 (26.5lbs)
    Cervelo SLC - SRAM Rival - Reynolds DV46T (16.25 lbs)

  11. #11
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    Anytime,

    It gets addictive bright bike lights...so be warey

    Stu
    What exactly is a rigid hard tail?

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