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Thread: DIY Helmet LED

  1. #1
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    DIY Helmet LED

    I'm looking to build a powerful helmet mounted LED.

    What are some of the more powerful LEDs that I should be looking at?

    I'm going to use a 5S 8Ah Li-Po battery for this and was wondering what you use as a LVC?

    Also wheres a good place to buy this stuff?

    Thanks!

  2. #2
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    The new MCE series from Cree are just out and produce tons of lumens,optics are limited right now, however u could get a P7 from Seoul and get more light, getting a good driver though seems to be an issue-2800ma full power.
    You could go the easy route and order a unit from Cutter.au and get over 1000 lumens in small package, they run about $250 without a battery.
    Cutter is one of the better suppliers, but it's in Australia so shipping takes a bit longer, they are prompt though and are very good.
    Many people use DealExtreme.com which is cheaper, free shipping but slow and unpredictable and quality is iffy on certain items-backordered and wrong item sent are the usual complaints.
    Good luck
    Eric S

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    I'm looking at those sites right now.

    I would like to keep this whole project under $200, but I already have the battery and charger, soldering stuff etc. I just need the light.

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    This http://www.cutter.com.au/proddetail.php?prod=cut757 one looks good, I'm still trying to figure out if I want to spend the extra $130 on the case or if I want to make my own. . .

    Would that driver work ok with a 18.5v (nominal) battery? I calculated that it would last 4 hours with 4 leds at 1000ma, does that sound right to you?

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    That should work, one thing to check though-if you're running a taskled driver, last years models are only good up to 20 volts max, this years are 25v. An 18 volt battery fully charged will be well above the 20 volt limit of last years driver. Mine is a 16.6v, fully charged it is 19.8v, that's 14 AA cells@ 2650mah
    I know this because I have 20 volt max driver on a homebuilt 4 Cree light and I can't add extra AA's to get me more burn time. I get about 3h 20m max @700ma-less @1000ma obviously.
    I do get some serious light with the Q5's though and 3:20 is usually enough time for me to get a ride in unless something happens...

    Eric S

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    How would the one I linked compare to 1 (or2) P7 LEDs? I'm more concerned about light output than anything else.

    Also what would a good light to use as a tail light? Would I be better off getting red LEDs or a normal LED with a filter?

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    Quote Originally Posted by bensf
    ... Also what would a good light to use as a tail light? Would I be better off getting red LEDs or a normal LED with a filter?
    Regarding tail lights, both options would be doable. But to be truthful, I'd recommend purchasing one (or preferably >1) of the better off-the-shelf tail lights instead. Something like 3 Basta SuperFlash units (say 1 on helmet, 2 on the bike) would make you highly visible for small $$$. The rationale is that COTS tailights are so light, cheap & effective that it's tough to match them with a DIY job. Much better to focus your creativity on building a badass helmet light I reckon.
    Brisbane, AU

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    Quote Originally Posted by bensf
    ... I'm going to use a 5S 8Ah Li-Po battery for this and was wondering what you use as a LVC?
    Thanks!
    OK, you really means business with that Li-Po battery-pack!

    I understand Li-Po offers very high energy density, but how much does that battery weigh?
    And were you planning to mount the battery on the helmet, or carry it in your pocket or backpack?

    One more consideration; unlike Li-Ion cells, Li-Po cells are easily damaged by over-discharging them, since they're generally not protected because R/C modellers don't care about battery life. Therefore you'll need to select a LED controller that can be programmed to shutdown when Vin (battery voltage) falls below some safe threshold. I believe some of the TaskLED controllers would do nicely.
    Brisbane, AU

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    Quote Originally Posted by hootsmon
    OK, you really means business with that Li-Po battery-pack!

    I understand Li-Po offers very high energy density, but how much does that battery weigh?
    And were you planning to mount the battery on the helmet, or carry it in your pocket or backpack?

    One more consideration; unlike Li-Ion cells, Li-Po cells are easily damaged by over-discharging them, since they're generally not protected because R/C modellers don't care about battery life. Therefore you'll need to select a LED controller that can be programmed to shutdown when Vin (battery voltage) falls below some safe threshold. I believe some of the TaskLED controllers would do nicely.
    What do you mean by RC guys don't care about battery life. I don't have a $200 battery lying around just because. I care about battery life. Hint Hint

    I was planning on using it in my backpack. I don't want it to get damaged either. Its 900grams, so its pretty heavy. It has the same amount of energy as a 20000mah 7.4v Battery.

    I have some GP3300s that I'm using to run my Halogen bar mounted light which I would like to use for the taillight as well. I already have one of the 5 LED CatEye ones, but i want more.

    The GP3300s are wired 7.2 in parallel. and have a capacity are 5500mah. (their old)

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    Just realized you meant built in LVC. heh. I've always thought of it as a controller based function.

    I like the one from cutter because of the high input voltage and the high level of programability. Also why don't more people use deans plugs on their lights. They have worked great for me.

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    Yep, I agree with you about Dean's plugs; they're robust, cheap and have good current-carrying capacity. In fact I've just built a cheap 'n cheerful battery-pack, consisting of 10x2500mAh NiMH cells, and it has a Dean's connector for compatibility with my balance charger. My thinking was this was the most economical way to get a battery-pack that'll support the new helmet-light project I'm planning, and it won't stop me getting in a Li-Po (most likely) pack with better energy density, a bit later once I have a clearer idea how much capacity is really needed.

    BTW, wasn't knocking R/C modellers at all, just pointing out that Li-Pos need some extra design precautions, to stop 'em getting damaged by over-discharging.
    Brisbane, AU

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    Yea I know, I read it again and i get what you were saying.

    that is the battery. It weighs less than my 12 NiMH cells with 4x the power.

    I'm thinking of using the bflex with the 4 LEDs. Anyone know what a good case for it would be?

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    Well in a helmet-light design that I'm currently hatching, I'm planning to use a remote battery-pack (like the one you've pictured), that just slips inside the jersey pocket (or Camelbak if I'm carrying one). Ideally it'd be nice to weatherproof your battery-pack, either with a layer of heatshrink plastic, or by rubber-dipping the whole pack. I couldn't find any heatshrink large enough at my local electronics-supply shop, so I have no idea where you'd obtain that stuff. Likewise, I don't know where you get the rubber-dip stuff from either.

    Regarding a housing for your helmet-light, the only limit is your imagination! There are numerous of off-the-shelf and DIY options available, depending on your skills, and what parts you can scrounge from other lights, etc. Just troll through earlier postings on this forum (as well as Candlepower forums) and you'll surely find something that fits your needs. For example, Znomit, troutie, dinnotte-style etc, etc... For my new light, I'm planning how to build a 'Znomit' inspired housing, but modified to take 2x MC-Es, and with a removable back-panel made from a cut-down Pentium heatsink.
    Last edited by hootsmon; 10-09-2008 at 10:04 PM.
    Brisbane, AU

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    My skills are high, just I'm lacking in tools. I'm trying to save up for a mill.

    You can get large size heatshrink from maxamps.com (although their batteries are overspeced and overpriced) The heatshrink and connectors are pretty reasonably priced.

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