Kickstarter Light technology
#76
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How well is the Magnic sealed? It contains an electronic circuit board, so water ingress could damage circuit boards unless they are waterproofed. And in mass production it's difficult to conformal coat all surfaces except the ones that provide electrical contact and maintain optical integrity. Or does it have a good drip control system?
#77
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Now on sale https://clevercycles.com/magnic-light-complete-set,, buy and try..
https://clevercycles.com/blog/2013/08...-magnic-light/
https://clevercycles.com/blog/2013/08...-magnic-light/
#78
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Because a bottle generator will have bearing friction, the magnets or coil spinning on an axis. It will also have some loss in the rolling surface interfacing with the tire. In this kickstarter generator it's the magnetic eddies that are moving, the flux lines cutting across fixed coils, so there is no mechanical friction. When I visualize this, all of the drag is directly related to the power generated, so I expect it to be more efficient in that sense than bottle generators. A hub generator, maybe not much difference but depending on the engineering.
We already know that the drag is greater than the ultimate power consumed by the light and we've got some pretty good data, here and there, on drag from various dynamos so that side doesn't really need any proving. The actual drag from this tech, yes I agree that we need some measurements to put the question to rest. That may be a little tricky for DIY tests though, since a coast-down doesn't get precise enough for that small amount of rolling drag and simply spinning the wheel unloaded doesn't actually translate to the drag on a loaded wheel. So we may have to wait for someone with more sophisticated equipment and a little time on their hands.
We already know that the drag is greater than the ultimate power consumed by the light and we've got some pretty good data, here and there, on drag from various dynamos so that side doesn't really need any proving. The actual drag from this tech, yes I agree that we need some measurements to put the question to rest. That may be a little tricky for DIY tests though, since a coast-down doesn't get precise enough for that small amount of rolling drag and simply spinning the wheel unloaded doesn't actually translate to the drag on a loaded wheel. So we may have to wait for someone with more sophisticated equipment and a little time on their hands.
As for weather sealing, the Magnic is completely sealed as there are no external moving parts or switches. Whether it is entirely waterproofed down to 50 feet is something else.
I have Canti's on my bike and it worked using their simple bracket that attaches to the brake pad holder. I think the bigger problem is disk brakes as there is nothing at the rim.
I agree that the position of the iight is a bit awkward. I mounted my taillight on the right side as you ride on the left on NYC's one-way streets. It is the accepted practice here even if it isn't a universal one. Buses are on the right. If you were close enough behind me on my left you may not see it, but by then its already too late!
#79
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Well, in one sense of 'better', the answer is clear: A SON or similar hub dynamo will drive a 90 lux (no expert here! but if I'm reading the numbers right, @15kph) Edelux II. The Magnic folks have claimed 16 lux* (@20kph).
*'Very bright' - Clever Cycles blog.
*'Very bright' - Clever Cycles blog.
#80
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Now on sale https://clevercycles.com/magnic-light-complete-set,, buy and try..
https://clevercycles.com/blog/2013/08...-magnic-light/
https://clevercycles.com/blog/2013/08...-magnic-light/
I wish the full set on the new kickstarter was 1 front 2 rear, but I went in on it and added a 2nd rear -- I was tempted by the old version, but the lack of a standlight was a deal-killer. I'm tired of batteries running out on my beater bike, but am not ready to go dynamo on a very old bike with a wheel size that doesn't match any of my others -- this way, if I upgrade the bike I can just move the lights.
#81
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Blog says they sold the 1st batch, maybe the next one has been upgraded
Yea Calhoun bike in MN sent me a B&M Lyt it had no standlighjt either
sadly this will be the stock Brompton thing..
they burned me bad when I returned it , and stuff like gouging me $20 for a short piece of wire to hook up the taillight .. that they omitted even sending in the 1st place..
a place to avoid ..
Yea Calhoun bike in MN sent me a B&M Lyt it had no standlighjt either
sadly this will be the stock Brompton thing..
they burned me bad when I returned it , and stuff like gouging me $20 for a short piece of wire to hook up the taillight .. that they omitted even sending in the 1st place..
a place to avoid ..
#82
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https://www.kickstarter.com/projects/...ess-bicycle-dy
This is the new one we've been talking about. Adds a standlight and is aiming to hit the German StVZO standard, which the first one didn't.
#83
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While bottle generators are another thing entirely, and have lots of drag due to friction, hub dynamos may or may not perform better than the Magnic. I don't really know myself yet. I don't have any capability to perform the measurements either. I will have both a Magnic light and a dynamo light available to me in April so I'll at least be able to do a test of perceived drag, if I can feel either.
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Added my Magnic review
Um, no. In actual real life usage, I can tell you unequivocally that the Magnic light is far more efficient than my Schmidt SON/IQ Cyo setup.
In any case, I wrote up a review of the Magnics that will hopefully answer provide some useful information as there seem to be plenty of questions and misinformation about them: https://www.bikeforums.net/showthread...-Magnic-Lights
In any case, I wrote up a review of the Magnics that will hopefully answer provide some useful information as there seem to be plenty of questions and misinformation about them: https://www.bikeforums.net/showthread...-Magnic-Lights
#85
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Ultimately, you could compare watts to drag or lumens to drag -- take your pick, but you're going to have to get quantitative data on at least two variables here.
You've given some quantitative data for the two lights in your other thread (i.e. you can feel the drag from one but not the other), but you haven't actually measured it that I can tell. And while you've talked about how bright they are -- 30 lux vs 60 lux -- note that lux doesn't tell how much light the light emits, only how much light reaches one particular point (the brightest area) or the average over an area that they consider to be "the" important area -- "lux" is quite vague and not suited to comparisons regarding efficiency.
Comparing average lumens (average, because many dynamo lights have a visible flicker) would be ideal, and if you want to compare beam patterns you could count only the lumens that go where you want them, but then it becomes subjective.
As for typical values, I've heard that hub dynamos are around 50% efficient (so a hub generating 3 watts of power would generate about 6 watts of drag if it was 50% efficient), and modern LEDs tend to put out about 100 lumens/watt. I don't really have any idea how efficient the magnic light's electrical generation would be, but I wouldn't expect their LEDs to be particularly unusual.
Last edited by dougmc; 01-15-14 at 07:58 PM.
#86
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The new kickstarter version (rather than the retail version) has a standlight, though. That's why this has bubbled back up.
I wish the full set on the new kickstarter was 1 front 2 rear, but I went in on it and added a 2nd rear -- I was tempted by the old version, but the lack of a standlight was a deal-killer. I'm tired of batteries running out on my beater bike, but am not ready to go dynamo on a very old bike with a wheel size that doesn't match any of my others -- this way, if I upgrade the bike I can just move the lights.
I wish the full set on the new kickstarter was 1 front 2 rear, but I went in on it and added a 2nd rear -- I was tempted by the old version, but the lack of a standlight was a deal-killer. I'm tired of batteries running out on my beater bike, but am not ready to go dynamo on a very old bike with a wheel size that doesn't match any of my others -- this way, if I upgrade the bike I can just move the lights.
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#87
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From what I gather people have been "overpledging" somehow and having it noted that they want a second rear light, to be followed up on upon delivery. There are more than a few messages about it on the Kickstarter project.
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I don't see how you can say that "X is far more efficient than Y" if you haven't 1) measured the electricity produced by X and Y and 2) measured the drag produced by X and Y. Since we're talking about lights, we probably should also 3) calculate the lumens/watt for their emitters as well. ...
AFAIK Dirk has investigated the actual system efficiencies. IANA electrical engineer so I can't pretend to follow it in great detail. There is some info here: https://www.kickstarter.com/projects/...ess-bicycle-dy (under What's new in Magnic Light iC?) regarding the LED efficienty but I'd love to hear him explain it in greater detail. I can ping him and see if he can provide something more substantial if you're interested.
#89
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Look at the comments/Q&A -- they're allowing people to overpledge and then in your "shipping info" ask for the other rear light. Not sure they'll allow an infinite number of different overpledge options, but this was a request of a lot of people. (I mostly want 1 front and 2 rear -- the bike I'm planning to put them on is a city commuter, and these will be additional visibility/running lights to the battery ones it already has.)
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Look at the comments/Q&A -- they're allowing people to overpledge and then in your "shipping info" ask for the other rear light. Not sure they'll allow an infinite number of different overpledge options, but this was a request of a lot of people. (I mostly want 1 front and 2 rear -- the bike I'm planning to put them on is a city commuter, and these will be additional visibility/running lights to the battery ones it already has.)
#91
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OK, I'll admit it was a mistake to say "unequivocally". The overall drag of the Magnics compared to the Cyo/SON is significantly lower.. a simple wheelspin test confirms that easily enough. Of course, the light output is a fair bit lower as well, so it gets a lot murkier in terms of overall system efficiency. Personally I haven't performed any tests that are anywhere close to scientific, so I can only tell you my conclusions based on my observations, namely that (and yes, I understand Lux is highly dependent on beam pattern) in my estimation the Magnics are roughly 1/2 as bright as the dyno setup but have far less than 1/2 the drag.
AFAIK Dirk has investigated the actual system efficiencies. IANA electrical engineer so I can't pretend to follow it in great detail. There is some info here: https://www.kickstarter.com/projects/...ess-bicycle-dy (under What's new in Magnic Light iC?) regarding the LED efficienty but I'd love to hear him explain it in greater detail. I can ping him and see if he can provide something more substantial if you're interested.
AFAIK Dirk has investigated the actual system efficiencies. IANA electrical engineer so I can't pretend to follow it in great detail. There is some info here: https://www.kickstarter.com/projects/...ess-bicycle-dy (under What's new in Magnic Light iC?) regarding the LED efficienty but I'd love to hear him explain it in greater detail. I can ping him and see if he can provide something more substantial if you're interested.
@dougmc: I applaud your rigor. I also support seeing some measurements. But on the optical side I think the ideal is to measure the ability to illuminate that which is useful to see, not to measure total light output, or electrical to optical energy conversion (lumens/watt). Depending on lumens to characterize optical output gives a product positive marks for spraying light where it isn't needed or might not be wanted.
A focus on lumens rather than illumination means that the best light is one with no light distribution control system - no light guides, lenses, reflectors, Fresnels, blackouts, et cetera. LEDs without lenses do not radiate full intensity into a 2pi space and the distribution is predictable, but it places a lot of its light where it might not be wanted or needed. Clearly one can use 10 degree (or narrower) factory-lensed LEDs to approximate spotlight functions. But that isn't what some of the better generator lights are doing (i.e. Lumos and Edelux 2), they are using sophisticated light distribution controls to approach the behavior of European automotive lights. For those of us who think that's the best model for bicycle light performance, illumination needs to be the target metric.
#92
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OK, I'll admit it was a mistake to say "unequivocally". The overall drag of the Magnics compared to the Cyo/SON is significantly lower.. a simple wheelspin test confirms that easily enough. Of course, the light output is a fair bit lower as well, so it gets a lot murkier in terms of overall system efficiency. Personally I haven't performed any tests that are anywhere close to scientific, so I can only tell you my conclusions based on my observations, namely that (and yes, I understand Lux is highly dependent on beam pattern) in my estimation the Magnics are roughly 1/2 as bright as the dyno setup but have far less than 1/2 the drag.
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FWIW, I'm a huge supporter of dyno light systems in general so I'm not trying to denigrate them at all. Just trying to convey my observations about the Magnics to an obviously skeptical crowd. I'd love to see an independent reviewer (Peter White or Jan Heine perhaps) do more rigorous testing when the iC lights are ready so we can get some true apples to apples results.
#94
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Because a bottle generator will have bearing friction, the magnets or coil spinning on an axis. It will also have some loss in the rolling surface interfacing with the tire. In this kickstarter generator it's the magnetic eddies that are moving, the flux lines cutting across fixed coils, so there is no mechanical friction. When I visualize this, all of the drag is directly related to the power generated, so I expect it to be more efficient in that sense than bottle generators. A hub generator, maybe not much difference but depending on the engineering.
We already know that the drag is greater than the ultimate power consumed by the light and we've got some pretty good data, here and there, on drag from various dynamos so that side doesn't really need any proving. The actual drag from this tech, yes I agree that we need some measurements to put the question to rest. That may be a little tricky for DIY tests though, since a coast-down doesn't get precise enough for that small amount of rolling drag and simply spinning the wheel unloaded doesn't actually translate to the drag on a loaded wheel. So we may have to wait for someone with more sophisticated equipment and a little time on their hands.
We already know that the drag is greater than the ultimate power consumed by the light and we've got some pretty good data, here and there, on drag from various dynamos so that side doesn't really need any proving. The actual drag from this tech, yes I agree that we need some measurements to put the question to rest. That may be a little tricky for DIY tests though, since a coast-down doesn't get precise enough for that small amount of rolling drag and simply spinning the wheel unloaded doesn't actually translate to the drag on a loaded wheel. So we may have to wait for someone with more sophisticated equipment and a little time on their hands.
I can easily agree with Zacster that the drag is imperceptible.
#95
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The Magnic cannot compete with a hub dynamo in terms of efficiency, because all it does is to replace the action of friction for a bottle dynamo, with Eddy current action, in transferring the rotation of the wheel to the rotation of the rotor in a dynamo. That transfer, necessarily lossy, is absent in a hub dynamo, since its rotor is rigidly attached to the wheel. The Magnic can have an advantage over a hub dynamo in terms of movability of the dynamo from one bike to another. However, wheels build over a reasonable dynohub can be had for about 60 euro in Germany - I am not sure about the US market. The price and the practical need to keep a dedicated Magnic mount on a bike really tame the incentive to use one. Still, I think it may be fun to employ a new technology just for the sake of it.
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Um, no. In actual real life usage, I can tell you unequivocally that the Magnic light is far more efficient than my Schmidt SON/IQ Cyo setup.
In any case, I wrote up a review of the Magnics that will hopefully answer provide some useful information as there seem to be plenty of questions and misinformation about them: https://www.bikeforums.net/showthread...-Magnic-Lights
In any case, I wrote up a review of the Magnics that will hopefully answer provide some useful information as there seem to be plenty of questions and misinformation about them: https://www.bikeforums.net/showthread...-Magnic-Lights
Last edited by Road Fan; 01-17-14 at 11:39 AM.
#97
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It seems that people have a hard time detecting the drag of a (good) generator while riding. So this doesn't seem right either.
Last edited by njkayaker; 01-17-14 at 12:06 PM.
#98
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This was one of my thoughts, too, earlier in this discussion. But while that loss of energy transfer is a down check to efficiency, it might be compensated by high intensity magnetic fields, lack of mechanical drag, possibly more efficient LEDs and possibly better LED drive strategy (i.e. lower current, more advantageous operating point). I still think it needs a test. I can't do it, however.
I suspect that the energy obtainable from the eddy currents is very limited (much lower than what is available from a generator hub). One issue is whether you can get enough light from the energy that can be produced.
We don't have any idea whether ratio of usable energy to drag is better than a hub generator. (Ideally, we'd want 100% usable energy to drag.)
Last edited by njkayaker; 01-17-14 at 12:17 PM.
#99
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You don't need the Magnic to take advantage of these. I'm skeptical that the LED's being used in the Magnic are any more efficient than what are being used in good generator lights.
I suspect that the energy obtainable from the eddy currents is very limited (much lower than what is available from a generator hub). One issue is whether you can get enough light from the energy that can be produced.
We don't have any idea whether ratio of usable energy to drag is better than a hub generator. (Ideally, we'd want 100% usable energy to drag.)
I suspect that the energy obtainable from the eddy currents is very limited (much lower than what is available from a generator hub). One issue is whether you can get enough light from the energy that can be produced.
We don't have any idea whether ratio of usable energy to drag is better than a hub generator. (Ideally, we'd want 100% usable energy to drag.)
Here is some detail on the magnets and LEDs he's using: https://www.magniclight.com/magniclig...rtseite/techno
Apparently something in the Cree Xb-D family.
Here is a chart about the LED efficiency, with accompanying text. Take from it what you will: https://s3.amazonaws.com/ksr/assets/...jpg?1387147866
2.Leds with 160 lumen per watt
The Magnic Light generator is tailored to the LEDs used, which reach almost 50% of the theoretically possible values- while good old standard systems barely attain 10-25 %:
Theoretically, the maximum white light you can obtain from 1 watt is appr. 350 lumen.However, good-quality LEDs only deliver about 40 lumen per watt (as used in many bicycle lights), which represents only 11% of the maximum. Light bulbs, on the other hand, only put out 10-15 lumen per watt, while theoretical maximum light possible is 685 lumen per watt (for green light). .
With high power LEDs one can reach appr. 80 lm/W, while the Cree LEDs used in Magnic Light deliver ~160 lumen per watt. This is possible because we feed each LED with less than 1 watt, which results in the ability to operate at temperatures below 35° C. This way, we harvest roughly 46% of the theoretical maximum white light, and hence 4 times more than standard LEDs.
Last edited by dhalbrook; 01-17-14 at 03:13 PM.
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As for whether or not other people could feel the difference, you're right, it's hard to say. The difference is pretty clear to me, but maybe others wouldn't notice it as much. That's why it was only a guess.
Last edited by dhalbrook; 01-17-14 at 03:14 PM.