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  1. #1
    Senior Member sonnetg's Avatar
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    Dynamo Powered LED lights and USB charger.

    Guys,
    I thought you'll might find this useful for touring. I put up a step by step instructions on Instructables.com. I certainly benefit from the USB charger and powerful lights. I hope you find it useful as well.

    http://www.instructables.com/id/Volt...amo-Light-USB/

    Any comments or suggestion would be welcome.

    Cheers.

  2. #2
    coprolite fietsbob's Avatar
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    Seems overly complicated.. I run a wired B&M topmount taillight on my rack,and a headlight .
    and a SON dynamo hub , but I don't own a cellphone and
    buy paper maps and Have a compass to find my way.

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    That's a lot of lights man, sweet!
    I don't think I'd like to ride just behind your rig at full power though

    I'm considering adding an Android smartphone for navigation on the bike, power supplied by my hub dynamo would be needed for longer rides. You have any idea what the output of your system is? The Minimal-Lader described at Fahrradzukunft (http://fahrradzukunft.de/12/minimal-lader/) is a bit different and does 707 mA at 20km/h (5,08 V).

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    It's OK to belong to the "old school", fietsbob, but I have an MP3 player that also can do videos; I have a mobile phone; and I have a camera that uses rechargeable batteries -- all things that are useful on a tour.

    The key will be hooking up a device to charge through the USB connection -- if it doesn't bzzt-die, then this could be very useful.

    Personally, I think it's worth investigating. Not that I am very good at soldering small components and circuits.

    Thanks sonnet.
    Dream. Dare. Do.

  5. #5
    Senior Member gregw's Avatar
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    I have been interested in the Dahon - Biologic Reecharge unit which I think essentially uses it's battery as the voltage regulator. How does your design compare to this?

  6. #6
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by fietsbob View Post
    Seems overly complicated.. I run a wired B&M topmount taillight on my rack,and a headlight .
    and a SON dynamo hub , but I don't own a cellphone and
    buy paper maps and Have a compass to find my way.
    If it works for you, fine. But, I absolutely need to stay connected and need my Smartphone. The supplementary LED flashlights and modded taillights were done more because it was fun, but is not needed (I also have a B&M frontlight and Toplight permanently mounted).

    The CREE flashlight can be a cheap solution for LED lights and is very powerful. I use it in a similar way one would use "high-beam" and to view far objects. The detachable taillight adds added visibility.

    Cheers.

  7. #7
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by gregw View Post
    I have been interested in the Dahon - Biologic Reecharge unit which I think essentially uses it's battery as the voltage regulator. How does your design compare to this?
    Hello,
    I am not familiar to Dhaons product. Can you point me to the product page or documentation.

    My gaddet is very simple. It can take an input anywhere from 6v-35v, and the output is always 5v (USB standard). With this 5 volts, I can power up CREE LED rated 4.5v charge my BlackBerry or MP3 player as well. Time permitting, i will add more features to it (eg add a rechargeable battery and current blocking diode).

    Regards,


    Note: I found the product, it seems it is depended on batteries. http://www.gizmag.com/dahons-biologi...rge-usb/15407/

    The main difference between my device and the Biologic Recharge is mine's does not use any batteries. Also, it only cost me less than $20 to built my device. However, down the line, I am planning to add a backup battery feature to power my devices when my bike comes at a complete halt.
    Last edited by sonnetg; 09-15-11 at 02:46 PM.

  8. #8
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by Lasse View Post
    That's a lot of lights man, sweet!
    I don't think I'd like to ride just behind your rig at full power though

    I'm considering adding an Android smartphone for navigation on the bike, power supplied by my hub dynamo would be needed for longer rides. You have any idea what the output of your system is? The Minimal-Lader described at Fahrradzukunft (http://fahrradzukunft.de/12/minimal-lader/) is a bit different and does 707 mA at 20km/h (5,08 V).
    You really brought up some interesting concerns. I am not really an expert in electronics, but let me do some further research on this. As far as I am concerned, the current drawn is depended on the device, but i could be wrong. I guess it's time to do some further testing using a MultiMeter. I will see what I can find out.

    Why not built this device and give it a try? I really hope Google/HTC is not as anal as Apple products (For most Apple devices to work, you will need the USB data pins to be a certain voltage. I am not able to charge my Ipod Touch with it, just yet. Damn Apple.).

    Good luck with HTC. I am sure they follow the USB 2.0 standard. Let us know hot it goes for you.

    PS: The output of this device will always be 5v (USB standard, no matter how fast or slow you go. [The input can be anywherefrom 6v-35v], but the current drawn may be depended on the dynamo and the device. You may have to refer to the manufacturer specification for the Dynamo/Device.
    Last edited by sonnetg; 09-15-11 at 10:41 AM.

  9. #9
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by Rowan View Post
    It's OK to belong to the "old school", fietsbob, but I have an MP3 player that also can do videos; I have a mobile phone; and I have a camera that uses rechargeable batteries -- all things that are useful on a tour.

    The key will be hooking up a device to charge through the USB connection -- if it doesn't bzzt-die, then this could be very useful.

    Personally, I think it's worth investigating. Not that I am very good at soldering small components and circuits.

    Thanks sonnet.
    You nailed it. Let me know if you need any help with soldering. I would be glad to help you out. It's very easy to build and solder, and I am sure you will be very happy with the end result. You can find almost any component from RadioShack or http://www.digikey.com/.

    Cheers.
    Last edited by sonnetg; 09-15-11 at 10:37 AM.

  10. #10
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    With only 3 watts out of most bike generators (alternators), it does not matter how much soldering you do, you are still only going to get 3 watts.

    I saw this bike in a bike rack a few months ago and had to take a photo of it. I think it takes the record for lights.

    reIMGP6868.jpgreIMGP6870.jpg

    I will continue to use the outlets at campsites and motels to charge my rechargeable batteries. And, if lucky occasionally find an unused plug in a restaurant.

  11. #11
    Senior Member sonnetg's Avatar
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    Yes. I agree with you. If you have access to hotels or power outlets, there is no need to use this USB device. There are always other alternatives and other ways to achieve the same goal. Whatever fits your bill. As for me, my phone battery can drain pretty fast when I use GPS, have phone conversations or web browsing. The USB device is more like a piece of mind rather than anything else, and it's always good to be self sufficient. You never know when you need it, emergencies and whatnot.

    As for 3 watts (6v x 500mA = 3 watt), you can stretch it quite a bit. It depends on the current rating of the bulb or LEDs. Most electronic devices depend on current (Amperes). While most LED's drain only 10-20mA of current, a bicycle Dynamo can provide up to 300mA-500mA of current (depends on the quality of the dynamo). (so in theory, you can easily light up 25-30 LEDs with a dynamo)

    An Iphone, Droid or Ipod can draw up to 600mA when the battery is completely drained, so if i plug an Ipod touch to the dynamo USB charger, the battery may charge at a slightly slower rate (Assuming the dynamo provides full 500mA).

    Here's an excellent article on USB devices and current: http://www.girr.org/mac_stuff/usb_stuff.html

    And another thing to keep in mind, which confused me as well, is Voltage vs Current. From what I understand:

    Voltage: you have to be careful with voltage rating because volts gets forced to the device (USB host will always push 5v to the device, regardless of the voltage rating of the device).

    Current: This is dependent on the device. If a devices is rated 10mA, it will only draw 10mA. If a device is rated 500 mA, it will draw that much current.
    Last edited by sonnetg; 09-16-11 at 01:25 PM.

  12. #12
    Senior Member sonnetg's Avatar
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    By the way....the bike in the picture that is insane amount of lights Better hope those are not battery powered.

  13. #13
    jaywbee3 jaywbee3's Avatar
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    I am about to start a 10 day self supported tour using a biologic to keep my Droid X charged. I have used it for short trips for the last two months and 4-5 hours of riding seems to give it a full charge which in turn gives me 1+ charges on the Droid. Or I can use it to power the droid while I ride and keep it topped off. I will let you know how it works on a longer tour in a couple of weeks.

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    I see two problems-

    If you aren't peddling fast enough, depending on the load, then the primary will sag, which will cause the output to go out of regulation. So the light will pulse- not a big deal, but some electronic devices that require 5V aren't so good with something that varies between 3V and 5V rapidly.

    If you're peddling too fast, then the regulator IC dissipates a bunch of power itself, which is inefficient. I'd rather not use up my hard-earned lunch making heat.

    But, a good first effort. Next would be a switching boost/buck regulator that uses 90% of the input power, and has a backup rechargable battery (that it charges while going faster) to hold the power up while going slower. That would be a product I would buy in a heartbeat.

  15. #15
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by cycle_maven View Post
    I see two problems-

    If you aren't peddling fast enough, depending on the load, then the primary will sag, which will cause the output to go out of regulation. So the light will pulse- not a big deal, but some electronic devices that require 5V aren't so good with something that varies between 3V and 5V rapidly.

    But, a good first effort. Next would be a switching boost/buck regulator that uses 90% of the input power, and has a backup rechargable battery (that it charges while going faster) to hold the power up while going slower. That would be a product I would buy in a heartbeat.

    Very good observation. I am actually debating between a super capacitor and rechargeable batteries for backup power. The problem is when i climb uphill, the LED's flicker quite a bit, and when i stop, i am pretty much in the dark :-)

    I need to configure two diodes and probably a rechargeable battery or two for backup power. That would be the next update.


    If you're peddling too fast, then the regulator IC dissipates a bunch of power itself, which is inefficient. I'd rather not use up my hard-earned lunch making heat.
    I haven't really measured the voltage output when pedaling fast. I only needed a regulator that wouldn't blow my LEDs. 5V regulator fit the bill. Even commercial Dynamo lights have some sort of voltage regulator built into them. I wouldn't necessary say the "heat" generated is a bad thing. It's only the access power that the LEDs dont need gets converted to heat, else the LEDs would be burning out. That's what I understand.

    Thanks for the suggestions. I can really see the demand for such a unit in Europe, India or other parts of the world. I would be surprised if there isn't anything out there already. (i guess most dont have much use for USB phone chargers

    I will work on the 2nd prototype, and see how that turns out.

    Regards,
    Last edited by sonnetg; 09-16-11 at 05:53 PM.

  16. #16
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by jaywbee3 View Post
    I am about to start a 10 day self supported tour using a biologic to keep my Droid X charged. I have used it for short trips for the last two months and 4-5 hours of riding seems to give it a full charge which in turn gives me 1+ charges on the Droid. Or I can use it to power the droid while I ride and keep it topped off. I will let you know how it works on a longer tour in a couple of weeks.
    I actually own a Dahon bike, yet i wasn't aware about the Biologic Reecharge. I am not sure how they set the price to $120. That's a bit too much to pay for a USB charger, not to mention the price of the Dynamo.

    Anyways, I am glad it works out for you. Good luck with your tour. I plan to do some touring in remote borders of India and south America, and I can see how critical a USB charger will be for me.

  17. #17
    Senior Member SweetLou's Avatar
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    Quote Originally Posted by Tourist in MSN View Post
    With only 3 watts out of most bike generators (alternators), it does not matter how much soldering you do, you are still only going to get 3 watts.
    This in not correct. Hub dynamos are a constant current source, not a constant voltage source. You can get much more than 3 watts from a dynamo. LEDs are also current driven, not voltage driven. This means if you are using LEDs that can draw the 500mA, like a Cree XLamp and connect them in series, then it doesn't matter how many you have. 500mA will pass through each one. The power (the watts) to do this will go up and must be supplied by the rider.
    Learn what's a platform pedal.

  18. #18
    Senior Member SweetLou's Avatar
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    Quote Originally Posted by sonnetg View Post
    As for 3 watts (6v x 500mA = 3 watt), you can stretch it quite a bit. It depends on the current rating of the bulb or LEDs. Most electronic devices depend on current (Amperes). While most LED's drain only 10-20mA of current, a bicycle Dynamo can provide up to 300mA-500mA of current (depends on the quality of the dynamo). (so in theory, you can easily light up 25-30 LEDs with a dynamo)
    Yes and no. It depends on how you have the LEDs connected. If they are in series, it doesn't matter how many you have. You could have 1000 LEDs and 500mA will pass through each of them. If you have the LEDs connected in parallel then each one will only get a portion of the 500mA.

    Think of it like a pipe of water (a series circuit) with two little turbines in the pipe. If you pour 500ml of water (the amps) down the pipe, then 500ml of water will pass through each turbine (the LEDs).

    Now, instead of just one straight pipe, you have a pipe that branches into two identical pipes (parallel circuit) with one turbine in each pipe. Since the water will flow equally through each pipe, then each turbine will only get 250ml to pass through them.


    And another thing to keep in mind, which confused me as well, is Voltage vs Current. From what I understand:

    Voltage: you have to be careful with voltage rating because volts gets forced to the device (USB host will always push 5v to the device, regardless of the voltage rating of the device).

    Current: This is dependent on the device. If a devices is rated 10mA, it will only draw 10mA. If a device is rated 500 mA, it will draw that much current.
    Volts don't get forced through a device. A volt is not an object. It is the measurement of voltage. Voltage is the pressure, it is what pushes the electrons (current) through the circuit. Using our analogy, it is how hard you push the water through the pipes. If you push too hard, you could break the turbines. If you don't push hard enough, the turbines won't spin and no water will pass through.
    Learn what's a platform pedal.

  19. #19
    Je pose, donc je suis.
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    Quote Originally Posted by SweetLou View Post
    This in not correct. Hub dynamos are a constant current source, not a constant voltage source. You can get much more than 3 watts from a dynamo. LEDs are also current driven, not voltage driven. This means if you are using LEDs that can draw the 500mA, like a Cree XLamp and connect them in series, then it doesn't matter how many you have. 500mA will pass through each one. The power (the watts) to do this will go up and must be supplied by the rider.
    Exactly. I had three CREE in series (700-1000mA) without much difficulty, probably using 8-10W by my calculations. I once calculated the voltage curve, resistance and internal inductance of my Shimano dynamo, and made my students calculate the lighting power -- then decided that it's self-regulating enough that I didn't need a voltage regulator (yes, lazy, but so far so good).

    [Edit: voltage regulator for the lights. Obviously, you need regulation if you're going to power things via USB.]

    The trade off is that you lose light at the low end, though.

    OP, if you really want to go DIY, find a place that will let you use their rapid prototype printer and design your own shell. I'd bet Johns Hopkins or UMBC has one the public can use, if you talk to the right person.

  20. #20
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by SweetLou View Post
    If you have the LEDs connected in parallel then each one will only get a portion of the 500mA.
    I am sorry, i would have to disagree with you. As far as I understand, the LEDs will draw whatever current it is rated for. In this case, a regular 5mm LED will draw 20mA, and a High Power CREE LED could draw 350mA-600mA (or more if the dynamo can provide). However, connecting the LEDs in series vs parallel will make a huge difference on how much volt will pass through them.

    Here are few useful articles on LEDs:

    http://www.instructables.com/id/LEDs-for-Beginners/
    http://www.talkingelectronics.com/pr...0Projects.html


    Volts don't get forced through a device. A volt is not an object. It is the measurement of voltage.
    Yes. That is correct. Volt it is a unit of measurement to measure voltage. I actaully meant voltage. And of course, voltage doesn't get shoved to the device either. I was giving an analogy. The links below will somewhat help understand what is voltage and what is current:

    Voltage: http://en.wikipedia.org/wiki/Voltage
    Current: http://en.wikipedia.org/wiki/Ampere
    Last edited by sonnetg; 09-17-11 at 11:05 AM.

  21. #21
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by Pedaleur View Post
    Exactly. I had three CREE in series (700-1000mA) without much difficulty, probably using 8-10W by my calculations. I once calculated the voltage curve, resistance and internal inductance of my Shimano dynamo, and made my students calculate the lighting power -- then decided that it's self-regulating enough that I didn't need a voltage regulator (yes, lazy, but so far so good).

    [Edit: voltage regulator for the lights. Obviously, you need regulation if you're going to power things via USB.]

    The trade off is that you lose light at the low end, though.

    OP, if you really want to go DIY, find a place that will let you use their rapid prototype printer and design your own shell. I'd bet Johns Hopkins or UMBC has one the public can use, if you talk to the right person.
    Very interesting. I noticed my CREE flashlight connected to the dynamo is much dimmer than when it's powered by a battery. The CREE LED is rated 4.5v-6v @ 1.0 Amp. Do you think my USB voltage regulator (LM7895) limits the current (< 500mA)? The brightness does not change when i pedal fast. I am guessing i need to lower the Amperage rating for the CREE LED. Probably any LED rated for 500mA-600mA would give me best results, when connected in series?

    I am glad you posted in this thread. I have a question. What is the most voltage that a dynamo (rated 6v) can generate? 12v @ 20 mph? It seems you don't use a regulator for the LEDs connected in series. I have burned out so many incandescent bulbs before, hence the 5v regulator idea.

    Regards,
    Last edited by sonnetg; 09-17-11 at 10:17 AM.

  22. #22
    Senior Member SweetLou's Avatar
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    Quote Originally Posted by sonnetg View Post
    I am sorry, i would have to disagree with you. As far as I understand, the LEDs will draw whatever current it is rated for. In this case, a regular 5mm LED will draw 20mA, and a High Power CREE LED could draw 350mA-600mA (or more if the dynamo can provide). However, connecting the LEDs in series vs parallel will make a huge difference on how much volt will pass through them.
    If you have enough current, the LEDs will use as much as they can use. In series, the current remains the same across all loads. You can't have more water going through one turbine than another. If you have a device that can handle 30mA and one that can handle 20mA, then only 20mA will pass through both. You can't push more current through the one and not the other. Think of the water analogy. If you have two valves, one that will allow 1 gallon of water pass per minute and one that will allow 2 gallons of water per minute. They are connected in series. There is a bottleneck at the 1 gallon valve and only 1 gallon will pass through the 2 gallon valve.

    In parallel, if the turbines are the same, they will both have the same amount of water (current) go through them. Let's say you have a 1000mA LED and a 20mA LED wired in parallel, then the current will be different. Again with the water analogy. The pipes branch into 2 pipes. With the same valves as above, if you pour 3 gallons of water into the pipes, then the 2 gallon valve will get the two gallons it can handle and the one gallon valve will get the other gallon.

    If you connect 10 20mA LEDs in series with a 100 mA source, you will get 20mA across each LED. If you hooked them up in parallel, you will only get 5mA across each one. There is only so many electrons, you can't magically make more.
    .

    Yes. That is correct. Volt it is a unit of measurement to measure voltage. I actaully meant voltage. And of course, voltage doesn't get shoved to the device either. I was giving an analogy. The links below will somewhat help understand what is voltage and what is current:

    Voltage: http://en.wikipedia.org/wiki/Voltage
    Current: http://en.wikipedia.org/wiki/Ampere
    Here's a very helpful article on LEDs: http://www.instructables.com/id/LEDs-for-Beginners/Sorry, but you are wrong. Again, voltage does not go through anything. It is the force that pushes what goes through it. Think of it as gravity pulling the water through the pipes. You wouldn't say that the gravity went through the valves.

    Quote Originally Posted by sonnetg View Post
    Very interesting. I noticed my CREE flashlight connected to the dynamo is much dimmer than when it's powered by a battery. The CREE LED is rated 4.5v-6v @ 1.0 Amp. Do you think my USB voltage regulator (LM7895) limits the current (< 500mA)? The brightness does not change when i pedal fast. I am guessing i need to lower the Amperage rating for the CREE LED. Probably any LED rated for 500mA-600mA would give me best results, when connected in series?

    I am glad you posted in this thread. I have a question. What is the most voltage that a dynamo (rated 6v) can generate? 12v @ 20 mph? It seems you don't use a regulator for the LEDs connected in series. I have burned out so many incandescent bulbs before, hence the 5v regulator idea.

    Regards,
    Of course your light won't get brighter. You hub can only produce 500mA, it can't produce any more. Hub dynamos are a constant current source. No matter how fast you pedal, the maximum it can produce is 500mA. When powered by the battery, a constant voltage source, you can get more amps through your LED.

    You can't lower the amperage rating for the Cree, it is what it is. Since LEDs are current driven, the more current you put through them, the brighter they will be. You can limit how much current gets there, but all this will do is lower the brightness.
    Learn what's a platform pedal.

  23. #23
    Senior Member sonnetg's Avatar
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    Quote Originally Posted by SweetLou View Post
    If you have enough current, the LEDs will use as much as they can use. In series, the current remains the same across all loads. You can't have more water going through one turbine than another. If you have a device that can handle 30mA and one that can handle 20mA, then only 20mA will pass through both.
    So, is it safe to light 20mA LEDs with a dynamo? Or is it drawing 500mA? (To keep things simple, lets say we only want to light one LED rated 20 mA). According to you, the LED will try and use up all 500 mA. if that is the case, shouldn't it burn out immediately?

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    Quote Originally Posted by sonnetg View Post
    Very interesting. I noticed my CREE flashlight connected to the dynamo is much dimmer than when it's powered by a battery. The CREE LED is rated 4.5v-6v @ 1.0 Amp. Do you think my USB voltage regulator (LM7895) limits the current (< 500mA)? The brightness does not change when i pedal fast. I am guessing i need to lower the Amperage rating for the CREE LED. Probably any LED rated for 500mA-600mA would give me best results, when connected in series?

    I am glad you posted in this thread. I have a question. What is the most voltage that a dynamo (rated 6v) can generate? 12v @ 20 mph? It seems you don't use a regulator for the LEDs connected in series. I have burned out so many incandescent bulbs before, hence the 5v regulator idea.

    Regards,
    It can actually generate quite a lot of voltage, because what SweetLou says is accurate. The dynamo is "trying" to push a certain current, so if there is a high resistance load, voltage will keep building up until the current is pushed. In my tests, I reached hundreds of volts, if I remember correctly (and burnt my finger on the resistor).

    Also, my calculations for a 3W/6V Shimano showed the limit to be about 1000mA, at which point the inductance limits the current. This is at odds with SweetLou's statement of 500mA -- I could certainly be off in my measurements. Nevertheless, I use two CREE's rated to 1000mA just to be safe.

    If you understand the math (second-order differential equation), I can dig up the numbers. If you don't care for math, we can just talk in generalities.

    LEDs are very sensitive to voltage, if powered with a constant voltage source (battery). If you look at the brightness curves for an LED, the difference between 3V and 3.5V can be huge. By limiting the voltage with your regulator, you _are_ limiting the current through the LEDs. The math gets a little complicated (or not).

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    Quote Originally Posted by Pedaleur View Post
    Also, my calculations for a 3W/6V Shimano showed the limit to be about 1000mA, at which point the inductance limits the current. This is at odds with SweetLou's statement of 500mA -- I could certainly be off in my measurements. Nevertheless, I use two CREE's rated to 1000mA just to be safe.
    Interesting, what hub was this? I haven't done any testing myself but if there is a hub that can produce 1000mA, I would be very interested in it. This would simplify some lighting systems I am thinking of making.
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