Unreasonably Bright Bike Light Apparently Hunts Deer


[Jukka] wanted a bike light that wasn’t afraid to go into the woods during the dark winter. He put together a lamp that uses eight 3 Watt LEDs to pump out 1680 lumens (english translation). The high power LEDs were mounted on a large aluminum heat sink and use lenses to optimize the beam of light. The system uses a 2 amp driver board that he assembled himself. Power is provided by sixteen AA Nickel Metal Hydride batteries that are housed along with the driver circuit in a water bottle.

This more than doubles the output of the last bike light we thought was too bright. Where will this lumen-arms-race stop?

[Thanks Sami]

79 thoughts on “Unreasonably Bright Bike Light Apparently Hunts Deer

  1. granted they would need to be focused, but what’s the hold-up on replacing car headlights with these? they would be more reliable than a standard or xenon bulb and use less power.

  2. @Dan: he says 1.5hrs on his page. But he mentions 0.9A right after, so I’m not sure if that is at full power.

    If you do basic calculations it should be under 2hrs at 24W draw. 1.2V * 16 cells * 2600mAH * 90% = ~45W/hr

    @djrussell: they are just too expensive. If you googled you would find them on high end cars, or as an option.

  3. Yeah… I wanna make a flashlight like this with a lithium polymer battery!
    With the 6 AH cell from sparkfun, 8 Luxeon Rebel LEDs would last for half an hour. Not bad if I build a car charger into it and keep it in my car. It would be crazy bright too! about $90 in LEDS though!

  4. jproach: they don’t look prohibitively expensive. especially not with auto industry bulk rates.

    insipid melon: as head lights? cite models please. the only ones i’ve seen are the audis with the accent strip underneath the actual head light.

  5. I’ve seen some of the higher end porsches with them as well.

    Why not make a generator that is run off of the pedaling motion or the wheel to charge a battery. That’d at least make the light output constant for the life of the rechargeable battery.

  6. if that thing gets any brighter he’ll be able to peel paint with the damn thing. wouldn’t mind have a few mounted on my bumpers, some in back for tailgaters who leave their brights on and some in front for… well seeing stuff.

  7. Another alternative is using the SSC P7 leds that are 10w and 900 lumens each. Which might also be bright enough to be used as supplementary lights on a motorcycle, where you are still relatively limited in power.

  8. “insipid melon: as head lights? cite models please. the only ones i’ve seen are the audis with the accent strip underneath the actual head light.”
    I am not a car person and if I were I still don’t know why you’d expect me to be able to identify cars which I am complaining blind me at night when I look at them. :p

    But there are enough of them in Abq. that I usually run into at least a few on night outings, and the cop cars are switching over to LED headlights as well. (they also have LED siren strips).

  9. I think with a little work you could make a nice pair of rally-style lights, and if you design it right you could have an adjustable throw pattern. Never hurts to be able to see further driving on country roads this time of year.

  10. “”Why not make a generator that is run off of the pedaling motion or the wheel to charge a battery. That’d at least make the light output constant for the life of the rechargeable battery.””

    Hmm this would increase resistance which i think every bike ride tries to avoid.. how ever if there was a break system which returns energy to the rechargeable battery then you are onto a winner.. That way every time you use your brakes it would add charge to your battery. this way you will get back something from that hard earned energy you put in to get the bike moving in the first place.

  11. I work at a bike store and I know all the bike lights. Current LED Units are pumping 1200lumins out of their highend systems with a reasonable runtime. Previously they were chucking out around 900-1000 with HIDs however the new LED stuff they are working with brings the cost down and the efficiency up drastically. Most brands have discontinued use of halogen and HIDs.

  12. What an awesome project! This is so well done not to mention simple! This is the kind of project where necessity meets fun. You know you’ve got to feel like a bad ass when your driving down the street and your blinding oncoming cars with your bike light! GJ on this project!

  13. via this thread saw a link for a 900lux $85 bike light
    On a side note just found out my surefire L2 lumamax has been upgraded to put out twice the power, twice the runtime, in a smaller package, for the same $! L2’s aren’t even in surefire’s vocabulary anymore! Only dif is mine goes 33ft, the lx2 does 3ft. L2 = 6W, 100lux, 1hr, or 15L/18hr ~.
    I was thinking of running one from the bike motor (1000W ecospeed) battery (15A 38V), but will wait & see as I want a 12V jack regardless.

  14. nice for a ride though the woods or as brights, but not so much as lights on roads with oncoming traffic.

    round reflectors throw light in a circular pattern in all directions, not just down, also up –not a problem with a couple leds: if a car gets a surprise, fine with me.
    but at this brightness, and if you really want to use it as headlight, one should have a look at headlight patterns: if you shine your car lights on a wall you notice two things:
    1. the beam isn’t round but forms a bar
    2. there is a clear cutoff line just above this bar.
    this cutoff line is basically required everywhere, and the bar-shaped beam directs the light to where you need it. it’s not total lumen that makes the light, it’s lux on the road. and with a good design you can save about 1/3 and get the same brightness.

    here a couple links:
    how to measure it (german bicycling club, go half way down the page): http://www.fa-technik.adfc.de/Komponenten/Scheinwerfer/index.html

    a commercial reflector that can do that:

    a homemade attempt:
    http://www.enhydralutris.de/Fahrrad/LEDWerfer0402/p1130815_s.jpg (the led is actually not mounted in the reflector but on the aluminum sheet)
    – done by this guy:

    more here:

    one of course could also add an anti blinding shield and point some of the reflectors downward.
    personally, i like elliptical lenses on a couple leds combined with a led in a modified spot (led with aluminum shield on one side)

    the whole problem got extensively discussed in germany (more bikes there), but to some degree also at candlepowerforums

  15. @rob
    some guy did tests with dynamos and got surprisingly good results:
    go down to #5 to get the circuit
    by removing the zener-diodes (over-voltage protection) in his wheel dynamo, he could power 4 white and 1 red led at 280ma while going 11mph.
    the text in red on top is a warning: if you do this with a hub dynamo and your leds get disconnected while your supercaps are still charging, you have to discharge them before reconnecting the leds or they will be toast.
    what surprised me: dynamos are apparently very good current sources and can drive leds directly, he got this graph http://www.led-treiber.de/assets/images/Dynamo-LED.gif on his page

  16. I’m not convinced the (only) way forward is a lumen-arms-race – if you’re not looking for real-colour vision at night, would it not make more sense to run lower power red lighting to maintain night vision AND illuminate the trail effectively? The one thing I hate with super bright lighting on bikes (and I currently have it) is the fact that you need to carry stupid amounts of battery power and several lights to create a fake-sun system, yet you still can’t look to your sides, and more importantly if something is slightly out of the side of your beam pattern it’s basically invisible because teh white light is trashing your night vision. With red (or to some extent blue, which I’ve tested) you can still see where you’re going just fine but you can also see everything around you like you’ve been in a dark room with the lights off, it means you can have much longer runtimes and if your pack does go flat you can still see where you’re going without waiting 10 mins to adapt!
    Not for everyone though, I’m aware.

  17. @alex – you don’t use this sort of bike light in a place where there are cars – a) you’d dazzle the car driver b) you’d be risking being pulled by the cops and c) its totally overkill – this kind of light is off-road only! I get flashed by annoyed cars with my 50W halogens, let alone mental LEDs!

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