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  1. #26
    Seņior Member ItsJustMe's Avatar
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    Working through eddy currents is pretty neat. Using LEDs at half their rated output to increase efficiency is an interesting approach, and at the prices LEDs are at, it's not a bad decision if efficiency is paramount.

    160 lumens is significantly substandard front lighting these days though. I wouldn't ride with less than about 200, and I wouldn't be happy at that. I really want 300 to 400 lumens up front at least, and that's in the easy parts of my ride. On the challenging bits, I want 800 or more.
    Work: the 8 hours that separates bike rides.

  2. #27
    Senior Member dougmc's Avatar
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    Quote Originally Posted by ItsJustMe View Post
    I really want 300 to 400 lumens up front at least, and that's in the easy parts of my ride. On the challenging bits, I want 800 or more.
    ... then what you want really isn't offered by any current dynamo-only lights of any sort that I'm aware of. I don't know of any dynamos that put out more than 3 watts, and at 100 lumens/watt for good modern LEDs -- that's 300 lumens. I mean, somebody could make a more powerful dynamo, but too much more drag and people won't like it -- even 3 watts from a 50% efficient dynamo is six watts of drag, which is going to be definitely noticeable.

    And I imagine that you're aware of all of that.

    That said, 160 lumens is way more than the reelights I have -- if it's 160 lumens steady, then that's well into the "help me see" category of light, where the reelights I have are strictly "help me be seen" lights. I'd guess that the reelights I have are maybe 25 lumens (well, the white front light) while flashing, and they're only on like 20% of the time (they flash), so an average of 5 lumens or so? (Just a guess, I haven't measured it.)

  3. #28
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    Quote Originally Posted by zacster View Post
    The movement of ANY conductor generates eddy currents. In this case, the aluminum rim of your wheel is a rotating conductor and it generates the current. The magnets inside the light then move to generate the electricity that powers your lights. This works even though the rim is non-ferrous.

    The real engineering feat here isn't the "magic" of the eddy currents, it is harnessing them in something small and light enough to put on a bike.
    It is not quite like that. The rim ends up being partly ferrous because of a steel insert needed to close the circumference of the rim. The Magnic reacts both to the Eddy currents and to the insert. From my prototyping, the insert contributes both positive and negative effects. Negative is in making the positioning of Magnic difficult. Eddy currents repel while the insert attracts. If the Magnic were positioned too close to the rim, it might get stuck to the insert. Too far and the effects of Eddy currents could be too weak. I read a report of some owner claiming that it took him an hour to position the Magnic correctly. That could erase the convenience of moving the light from one bike to another, but I lack personal experience other than with a coarsely put together prototype.

  4. #29
    Senior Member JonnyHK's Avatar
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    Quote Originally Posted by 2_i View Post
    It is not quite like that. The rim ends up being partly ferrous because of a steel insert needed to close the circumference of the rim. The Magnic reacts both to the Eddy currents and to the insert. From my prototyping, the insert contributes both positive and negative effects. Negative is in making the positioning of Magnic difficult. Eddy currents repel while the insert attracts. If the Magnic were positioned too close to the rim, it might get stuck to the insert. Too far and the effects of Eddy currents could be too weak. I read a report of some owner claiming that it took him an hour to position the Magnic correctly. That could erase the convenience of moving the light from one bike to another, but I lack personal experience other than with a coarsely put together prototype.
    Pretty sure there is no steel in an alloy rim. The pinning section is alloy too. Many rims are welded now as well.

    Like most things, the initial set up might be hard - but once done all you do is click on and click off. I'd get two sets of mounts if I was swapping between bikes often.
    Last edited by JonnyHK; 01-03-14 at 06:58 AM.

  5. #30
    tcs
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    Quote Originally Posted by dougmc View Post
    I don't know of any dynamos that put out more than 3 watts...
    Alibaba, Amazon and ebay can fix you up with 12V, 6W dynamos in singles or by the ISO container - all you need is a charge card number (preferably your own).
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  6. #31
    tcs
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    So do Magnic lights work with steel rims with the available brackets?
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  7. #32
    tcs
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    Quote Originally Posted by 01 CAt Man Do View Post
    If I can buy one front light for less than $100 ( even if max output is about 160 lumen ) it sounds like the money spent may be well worth it if I never have to worry about having to run out of battery juice. For winter commutes it could be just the thing to give the dedicated battery lamp user some added peace of mind.
    For back up peace of mind, consider a std. front dynamo.

    golden cat.JPG

    I know, not so high zoot - but just $15 instead of ~$100. Put the money you save into better primary lighting.
    Last edited by tcs; 01-03-14 at 09:19 AM.
    "When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

    "Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

  8. #33
    rugged individualist wphamilton's Avatar
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    I think this technology is likely superior to the traditional dynamos, and I hope they succeed to the point of larger scale production. I'll buy one.

  9. #34
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    Quote Originally Posted by JonnyHK View Post
    Pretty sure there is no steel in an alloy rim. The pinning section is alloy too. Many rims are welded now as well.

    Like most things, the initial set up might be hard - but once done all you do is click on and click off. I'd get two sets of mounts if I was swapping between bikes often.
    OK, I checked different rims around the house with a magnet and indeed the situation depends on the rim. It so happened that the couple of rims I used for testing my prototype both had steel inserts but some rims around the house do not. Another factor emerged, though, as a source of potential trouble and these were the steel wire beads that want to cling to a magnet.

    Regarding the mounts, would that be one for the front, second for the rear and maybe still one more for the front for the other side??

  10. #35
    Senior Member no motor?'s Avatar
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    Quote Originally Posted by wphamilton View Post
    I think this technology is likely superior to the traditional dynamos, and I hope they succeed to the point of larger scale production. I'll buy one.
    I'd be tempted to do the same, but only for a backup system.

  11. #36
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    There is no difficulty in positioning the light once you have the mount on. The magnets in the light don't just clamp onto the nearest ferrous material. I only had problems getting the mount onto the brake caliper because I didn't have quite a long enough bolt. The light itself just clicks on and off the mount.

    As for the power/lumens/lux it generates, it does come in at the low end of what would be considered adequate. 30 lux is pretty low for a front, but you would want to use 2 so 60 lux would put it in the mid-range dynamo light category from B&M. I'm still in the process of building up a dynamo wheel and light set for my commuter to compare with the battery lights I currently use. My current lights are a Lezyne Super-drive and a cheap Chinese Keygos flashlight, both around 450 lumens. So, how do you compare lumens, the rating used for battery lights typically, with lux, the rating used on Stvzo compliant dynamo lights? That's a whole different argument.

    I think the problems you encountered were the types of things that Dirk had to surmount to make it viable, and that's what he has done. Yes, you can make a prototype, but he made it commercially available, although if you read his story he had lots of problems along the way and then was helped by some people in China in manufacturing. I don't envy him for what he is going through to make a product. He could easily go broke doing this, and I guess that's where the kickstarter campaign comes in.

  12. #37
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    Quote Originally Posted by no motor? View Post
    I'd be tempted to do the same, but only for a backup system.
    Why only as a backup? If it works it easily replaces a battery system. The battery would be the backup since this is always on.

  13. #38
    Senior Member no motor?'s Avatar
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    Because I need more light when I ride.

  14. #39
    rugged individualist wphamilton's Avatar
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    Quote Originally Posted by no motor? View Post
    Because I need more light when I ride.
    That, and I'm thinking primarily for the tail light.

  15. #40
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    Quote Originally Posted by no motor? View Post
    Because I need more light when I ride.
    That's what I'm testing with a dynamo setup. I'm happy enough with my battery lights (I only use one at a time). I get complaints though that they are blinding. So is 450 lumens of light that goes in all directions better than 70-90 lux of a directed non-blinding beam, even if the lumens are much less?

    Now that I have ordered all the parts, it snowed here in NYC so I'm done until the roads are clear and dry.

  16. #41
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    Quote Originally Posted by wphamilton View Post
    That, and I'm thinking primarily for the tail light.
    For a tail light, this thing is more than enough. It was clearly visible during the day.

    (And another disclaimer: I have nothing to do with Magnic Light. I just seem to be the only BF member that's ever tried one.)

  17. #42
    Senior Member no motor?'s Avatar
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    Quote Originally Posted by zacster View Post
    So is 450 lumens of light that goes in all directions better than 70-90 lux of a directed non-blinding beam, even if the lumens are much less?
    For me it is, but I ride with more lumens than that most of the time. Let me know when they come up with a dimmer light that will let me see up hills and around corners like my current lights will, as well as let me see when I'm riding in traffic with a lot of ambient lighting and we can compare lighting then.

  18. #43
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    Quote Originally Posted by no motor? View Post
    For me it is, but I ride with more lumens than that most of the time. Let me know when they come up with a dimmer light that will let me see up hills and around corners like my current lights will, as well as let me see when I'm riding in traffic with a lot of ambient lighting and we can compare lighting then.
    And that's what I'm going to do, compare. It'll be a real world test, with my new SJ1000 video camera to record it.

    When I'm out at night I'm only riding in Manhattan or Brooklyn. What I really want to see is if the directed beam is as visible to pedestrians as my blinding flashing light. Somehow I don't think it will be. But then the question is whether it is visible enough.

  19. #44
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    It seems like an interesting technology. Touring cyclists are often interested in charging devices via USB (phones, GPS, tablets, etc), and if camping, may not have outlets at their site, or have to compete for one in the restrooms, or libraries, or cafes, then sit and watch their gear to prevent its certain theft for the entire charging time.

    Can this be adapted to charge a lithium battery pack during the day? I could then see the pack being used to run extremely bright lights if necessary, or charge devices. It seems much less hassle then the currently troublesome solar charging solutions.

  20. #45
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    Quote Originally Posted by stevepusser View Post
    It seems like an interesting technology. Touring cyclists are often interested in charging devices via USB (phones, GPS, tablets, etc), and if camping, may not have outlets at their site, or have to compete for one in the restrooms, or libraries, or cafes, then sit and watch their gear to prevent its certain theft for the entire charging time.

    Can this be adapted to charge a lithium battery pack during the day?
    In principle yes, but according to the maker of it the output is less than 1 W at 30 km/h so the charging rate would be rather low.

    I haven't had a problem finding outlets to charge my batteries on tours. If there isn't a convenient one at a campsite I'll ask at a restaurant where I stop for breakfast. Since I use a cheap charger for my AA cells I haven't been concerned about the possibility of theft (devices with built-in batteries then get charged from an AA pack) and carrying a little multi-outlet plug eliminates the competition for a single outlet problem.

  21. #46
    rugged individualist wphamilton's Avatar
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    Quote Originally Posted by zacster View Post
    For a tail light, this thing is more than enough. It was clearly visible during the day.

    (And another disclaimer: I have nothing to do with Magnic Light. I just seem to be the only BF member that's ever tried one.)
    That's what I meant. I'd love to have one for the tail light. I'm waiting for second generation though, because that's a general habit with me.

  22. #47
    Senior Member 01 CAt Man Do's Avatar
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    Quote Originally Posted by ItsJustMe View Post
    ...160 lumens is significantly substandard front lighting these days though. I wouldn't ride with less than about 200, and I wouldn't be happy at that. I really want 300 to 400 lumens up front at least, and that's in the easy parts of my ride. On the challenging bits, I want 800 or more.
    Yeah, I can agree with that. One thing that battery lights do is spoil you.
    I know that 160 lumen is not a lot of light but 160 lumen can be quite useful depending on the type of beam pattern. With a more narrow beam pattern in mind I could probably ride without too much problem. That doesn't mean I wouldn't want more light only that I could ride and not have a major problem. I have various lamps and torches that have modes close to 160 lumen. There was a time I used to ride with that level of light a lot. Not so anymore.

    My Gloworm X2 has a sub-mode "low" that is listed as 150 lumen. The Gloworm people are pretty careful about how they rate their lamps so I'll take their word that it's a true 150 lumen. That said it puts out a very usable beam pattern and comes in handy for those long slow climbs. Of course with 1500 lumen at my disposal rarely do I run only the sub-low mode.

    After some consideration I don't know that I'll buy one. Since I rarely ride longer that three hours at night I really don't have the need for such a lamp. However if I ever planned on some kind of epic all night adventure ( which I'm not ) having a lamp like this could be very useful.

  23. #48
    Senior Member JonnyHK's Avatar
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    Quote Originally Posted by wphamilton View Post
    That's what I meant. I'd love to have one for the tail light. I'm waiting for second generation though, because that's a general habit with me.
    This one is the second generation and the addition of the stand light function seems to have been a factor in the success of the Kickstarter campaign. It is at 150% already.

    I'm in to equip my audax/touring bike. I might get a second set of mounts for my other bikes if all goes well.

  24. #49
    Senior Member 01 CAt Man Do's Avatar
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    I got thinking about this again. Nice little light it is but I can't help but wonder it you added a couple ( or more ) of the magnet/coil assemblies together in series connected to a single lamp if you might get a brighter more useable output. Give me an output ( from one lamp ) in the 500 lumen range and I'm in.

    I think someone else mentioned that is would be nice to be able to mount the lamp head "over" the front wheel ( like a standard dynamo lamp ). I like that idea. Perhaps if these smaller units become popular it will lead to something like I am suggesting.

  25. #50
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by unterhausen View Post
    I don't think the name was intended to imply magic, unless it's in a different language. I have to say I was a skeptic, but a lot of us didn't think about the spokes playing in the physics of it. It's really a pretty amazing invention
    I agree that it is an amazing invention. Spoke current is an interesting thought, that there is an electric circuit that involves the spokes. So a potential is created, current flows through the spokes, fork blade, brake caliper, and the body of the Magnic. In order to close the circuit across the gap between the Magnic and the rim, the current would have to be an AC current, not a DC current.

    I don't know if I agree, but it's an interesting hypothesis, not implausible. It could easily be tested by making sure the mount of the Magnic is not conductive. If it isn't conductive, current cannot flow and the light won't work. If the mount is already non-conductive and the light does work, then Unter's spoke circuit hypothesis would be disproven. There is a plastic element in the mounting system, the little snap-bracket that looks like the one that holds a Planet Bike taillight to a seat stay bracket. If anyone with a Magnic can measure the resistance (with an ohmmeter or DMM with this function) from the Magnic to the hub, we could test this hypothesis.

    Another hypothesis is that the passage of the rim through the magnetic field creates a potential along the rim, spanning the width of the assembly of magnets. A current should then be present in the rim, circulating through its circumference and spokes. Impedance of the spokes should be a lot higher than that of the rim, so rim current should be the dominant effect. But unless that current is AC and the magnet and windings serve as a sort of gapped transformer sensing the current in the rim, I don't see how energy represented by rim current is transferred to the Magnic, to power a small dynamo that actually runs the LEDs.

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