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  1. #1
    GATC
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    expensive headlight

    Is there a functional argument to be made for a generator hub plus lamp(s) rather than the brightest LED money can buy, or a HID, in the multi-hundred dollar price range of headlights?

    No batteries (no need to charge, no need to strap them to the frame) is excellent. No light when stopped in traffic, not great. No wheel swapping (I keep snow tires on a spare set of wheels right now) somewhat of a downer. Easy (enough) fork crown mounting is nice (if bar bag is taking up the handlebar real estate).

    I realize this might be an angels-dancing-on-pins kind of question, appreciate your patience...

  2. #2
    DNPAIMFB pinkrobe's Avatar
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    Quote Originally Posted by HardyWeinberg View Post
    Is there a functional argument to be made for a generator hub plus lamp(s) rather than the brightest LED money can buy, or a HID, in the multi-hundred dollar price range of headlights?
    Well, the function's the thing, isn't it? You can measure characteristics of a light system like lumens, width of beam, weight, battery life, etc., but the most important thing is whether it does what you want it to. It's subjective for the most part, although most would agree that more lumens = better. My personal preference is for a very bright light [comparable to 13W HID or better] with a bit of spill to the side that has at least a 4-hour runtime. It must be lightweight and rustproof, and should work equally well on handlebar or helmet. So, a generator-based system is not for me, since I know of no dynamo that would generate enough energy to pump out that much light.
    Proud Member of the HHCMF
    '06 Cervelo Soloist Carbon | '09 Titus El Guapo | '09 Misfit diSSent | '09 Wabi Lightning

  3. #3
    Zoom zoom zoom zoom bonk znomit's Avatar
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    I ran a 3w lumotec halogen off a shimano hub a few winters ago. Worked great as a commuter light. Super convienient.

    There is some discussion over on candlepowerforums about efficient circuits. I think they are getting 10w out of these things, which is plenty if you're using LEDs.

  4. #4
    Year-round cyclist
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    Quote Originally Posted by HardyWeinberg View Post
    Is there a functional argument to be made for a generator hub plus lamp(s)?

    No batteries (no need to charge, no need to strap them to the frame) is excellent. No light when stopped in traffic, not great. No wheel swapping somewhat of a downer. Easy (enough) fork crown mounting is nice...
    Those are all great considerations. My main ones were:

    – A set of decent headlights that provide good light on the road without blinding oncoming traffic. In that regard, I wish someone would manufacture a battery headlight with a beam pattern similar to that of a car headlight (which is more or less what you get with an E-6... albeit much narrower).

    – No need to time your ride. You get a strong headwind and ride more slowly? No problem! You won't run out of power!

    – Permanent installation on the bike, without ugly wires dangling all around.

    – If you go for a wired taillight (I didn't), you get single switch operation.

    As for the "no light when stopped" problem, I use a Planet Bike Beamer 5 or Blaze on my handlebars. This either provides redundancy, extra light when stopped or in steep hills, or a flasher for those heavily lit commercial districts. It's also for visibility and redundancy that I always run more than 1 taillight.
    Michel Gagnon
    Montréal (Québec, Canada)

  5. #5
    Scott n4zou's Avatar
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    I built a hybrid lighting system for my touring and commuting bike. This is its simplest form.



    The Ni-MH batteries were scrounged from a 9.6-volt R\C battery pack found on clearance sale at my local Wal-Mart. I cut the case open, separated the 8 cells and parallel connected the two 4-cell packs for about 5-volts at 2.4aH. This gives me hours of stand time so the lights never go out unless I open S1 to turn them off. The battery pack also works as a voltage and current regulator. The batteries will load the dynamo and automatically regulate the voltage just a few tenths of a volt above there rating. Bicycle dynamos are constant current devices. They force rated current into the circuit unless you have a current "sink" to absorb the unused current by the load connected to it. Hook up a 350mA LED to a dynamo without a battery and you'll measure 500mA across it no matter how many resistors or capacitors are in the circuit. This will eventually damage the LED's. Hooking up the battery pack provides a place for the extra current to go and be stored for later use by recharging the battery pack. A Luxeon 1-watt LED drawing 350mA with a 4.9-ohm resistor is used with the headlight. I put a 5000 MCD LED in the taillight. This 10mm LED was obtained at Radio Shack. It's rated at 1.9 volts and 36mA. With the 100 ohm resistor it's actually drawing 30mA @ 1.8 volts. When the dynamo is producing full power 120mA is recharging the battery pack. When riding the bicycle with dynamo engaged the battery pack would be draining into the LED's below 8 MPH. The amount of discharge is lowered as you approach 8 MPH. At 10 MPH the dynamo is supplying maximum voltage and current. The dynamo saturates above 10 MPH so it can't produce more voltage or current damaging the LED's and battery pack. If you don’t stop very often you must disengage the dynamo from the tire or if using a hub dynamo open S2 to prevent overcharging the battery pack. If you are in slow traffic or stopping a lot and discharge your battery pack to the point the LED's stop illuminating you must open S1. When you start moving again you can close S1 allowing the LED's to illuminate and provide slow recharging for the battery pack. During daylight hours you can open S1 and engage the dynamo with the tire or if using a hub dynamo close S2 and rapid charge the battery back with 500mA of current. This happens to be the suggested rapid recharge current for Ni-MH batteries! No battery charger control circuits required.

    You can include an LED driver chip and circuit if you would like automatic control of the headlight LED when the battery pack is depleted. Here is an example circuit.

    This circuit will automatically disconnect the batteries from the LED when the batteries are depleted. The Driver will turn the headlight LED back on when you start moving just like a typical no-battery dynamo lighting system. You can add a solar panel for effortless daytime recharging. Just connect it up to the battery pack with S1 open and the dynamo disengaged or S2 open.

    I built my headlight with a Luxeon LED and Fraen holder/lens system from http://www.luxeonstar.com/ . I ordered the elliptical pattern so it is like an automotive headlight.
    http://www.luxeonstar.com/item.php?i...HS-HEB1-LB01-H

    I have over 300 miles of nighttime riding on my system. My LED driver has never shutdown the LED at stops or when I disengage the dynamo for hill climbing. Whenever I check the battery pack I've never found it below 90%. Sometimes I need to disengage the dynamo to prevent overcharging!

  6. #6
    Senior Member
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    I had a really nice, quality, european generator light with a halogen headlamp for commuting
    and used that in the 1980s. I eventually moved on to other forms of light generation because
    the bike that the halogen generator light was on was stolen. When the bike was found and
    recovered, the bike had been vandalized and the light was trashed. Bummer.

    Let's just say this morning was a good argument for HID or decent halogen lighting. It was
    dark, cold, and motorists just can't see feeble little lights. You need a 100 ton gorilla and
    they definetely gave us a wide berth this morning.

  7. #7
    GATC
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    Wow Scott that is something!

    Can you hang 2 dyno-halo lamps off the fork crown or do they need to be mounted on the fork blade if you're going to put two down there somewhere? Can you squeeze them between a front rack and cantilever brake paraphernalia if fork blade mounting is required?

    ASB doesn't sound thrilled w/ 1 (or 2?) dyno halo lamps for fog vis. That would be an issue for me in the rainy season, due to start any day now. But my 15W NIMH halo I'm pretty happy w/ for that purpose at least, so I haven't felt the need to go HID yet.

  8. #8
    Scott n4zou's Avatar
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    Quote Originally Posted by aliensporebomb View Post

    Let's just say this morning was a good argument for HID or decent halogen lighting. It was
    dark, cold, and motorists just can't see feeble little lights. You need a 100 ton gorilla and
    they definetely gave us a wide berth this morning.
    If it's legal to run green lights in your state you can opt for a green LED. Green will get you noticed in traffic as the "sick" metallic green color produced by high power LED's appears extremely bright to the human eye as it's so sensitive to that color. Night vision phosphor screens are green for that reason. They could make phosphor screens for night vision equipment in any color but green is the best choice. I use a green LED in my headlight. Green can be hazardous to the eye due to the fact your pupils will not react to the green color and remain wide open. This is a distinct advantage, as you can't lose your night vision from the light being reflected from street signs and that sort of thing. On the other hand it's extremely harsh for oncoming traffic or other cyclists. I've seen cars give up and pull over to the side of 2-lane roads and wait for me to go by before continuing. Be advised some states have already made green LED lights illegal. Check your local traffic regulations before you "go green". Recently a policeman stopped me about my green headlight as it blinded him. I informed him that the Code of Alabama allowed green to be used front, side, and rear of vehicles. He looked it up and agreed but still said it was dangerous as it was so bright. He could not believe it was only a 1-watt LED and was "technically" 1/3 the power of 3-watt filament clearance or marker lights. He let me go but advised me to replace the green LED with a white light. No way am I doing that! Not until Alabama outlaws them like other states have.
    http://www.luxeonstar.com/item.php?i...rtno=LXHL-MM1C

  9. #9
    Scott n4zou's Avatar
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    Quote Originally Posted by HardyWeinberg View Post
    Wow Scott that is something!
    Thanks!
    I'm still in the design, test, and reliability stage so it's ugly right now.

    The switch, resistors, and diode board are exposed and a terminal strip allows connecting volt and current meters easily as I change configurations. I'll be adding battery control circuits soon so I cant overcharge my batteries. This will also make operating with hub dynamos automatic.

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