Magnic Light: contactless bicycle dynamo light

[Martin]

Today, I tried my MagnicLight-like rotor on a STEEL RIM.
Neither the N-S-N-S-N-S-type nor the N-N-N-N-N-N-type rotor did spin.
It seems, the ferromagnetic effect holds the rotor in one position !

I suspect the real Magnic Light shows the same behavior. However, Dirk's FAQ says that the Magnic works with ALL standard wheels except full-carbon wheels. Shouldn't that include steel rims ?

2_i, do you have means to test out a steel rim ?


To Steve: Shower Headlight with Twofish mount. Lights the trail and washes the bike after the ride.

 

[2_i]

Martin, I was planning to try out the steel rim tonight, but have now a major panic at my job. Come to think of it, a uniform ferromagnetic can only work through hysterisis and the nonuniformity in the ferromagnetic properties should be essential in providing the jolt to the rotor. The Eddy should still remain and the reason you get your rotor stuck is likely that the ferromagnetic pull is so strong that the enhanced friction on your rotor's axle prevents it from rotating. A stainless steel bearing in Magnic could do the trick.

 

[lampeDépêche]

To Steve: Shower Headlight with Twofish mount. Lights the trail and washes the bike after the ride.

Oh, man--that is *too* funny! I love it!

Actually, there have been many rides in the summer when I would have paid anything to have a nice spray-head pointing backwards at me as I rode.

 

[2_i]

2_i, do you have means to test out a steel rim ?

Martin: quick testing trying to rotate a steel rim, using a round magnet on a Dremel tool, produced a very vigorous rotation. Even if nonuniformity in the ferromagnetic properties were required, there is no problem with it being there. The rim is not perfectly true and, in addition, the strong magnet pull makes the rim vibrate. The numbers will have to wait until tomorrow, after I stabilize my work situation.

 

[Steve K]

To Steve: Shower Headlight with Twofish mount. Lights the trail and washes the bike after the ride.

Now that is worthy of a Kickstarter project!
Love it.

 

[Martin]

Tried that again with the STEEL RIM: What happens is that my 6-magnet rotor (N-S-N-S-N-S) points one of its poles towards the rim and is hard to rotate away from this position. It takes some force to "step" it to the adjacent magnet. This force clearly has to overcome the magnet-rim attraction, not the bearing friction.
A position between two poles is not stable, the rotor will immediately adjust so that one magnet pole points directly at the rim.

If rotating the steel rim, a close magnet is still being pulled towards the rim but not in the direction of rotation. Rotating or not rotating the rim, there's no difference. A nearby rotor remains stationary.
I tried the rotor at different distances to the steel rim and it never spun.

By now I'm pretty much convinced that the Magnic Light doesn't work on steel rims, though it works nicely on Al rims.


Just today, Dirk updated his Kickstarter page: He sais that some pieces will only arrive early January, so shipping of lights will happen later in January. He also shows the product packaging. And he mentions a protection box for storage of the light.

 

[2_i]

I could not get a rotation of the rotor with a spinning steel rim either. I.e. occasionally I got half a rotation, but it was as often in the direction of the rim's spin, as against.

 

[conrad52]

Just tested now using a 6p (p-n-p-n-p-n) magnet, as soon as the rim rotates the 6p magnet rotates as well.
Here below the magnet detail:

... and here below how it rotates ...


CONCLUSION:
"Eddy components" definitely prevail on "Magnetic attraction"

 

[EnabLED]

of the order of 58% of power from the Magnic device is produced by the ferromagnetic effect and about 42% by Eddy currents. The error in my measurements can be easily 5-10%.

Even with 10% error, this suggests Magnic light users could get significantly more power by using the right combination of parts.

Further, it suggests with only a little weight penalty, one could make an aluminum/aluminium rim with steel inserts that have little added weight but significant increase in power output. Notably, if the goal is more light than the current Magnic light, the choice between a few grams of steel in the rim or some much heavier generator might favor a few grams of steel in the rim.

If so, what is the ideal distribution of steel? For example, it might be possible to place a light steel wire in the rim's hollow cavity. For a given weight of steel, would it be best to have a round wire, a flat strip, a wavy "snake", or...? Or would it be better to have a series of short segments, or ...?

(For anybody reading this who wonders "why not just use a steel rim?", it turns out there's a couple good things about aluminum rims -- wet rim brakes work much better on aluminum rims, and it is much easier to make an aluminum rim which is light, stiff and strong. So even though an aluminum rim with steel inserts sounds silly, if it helps to increase Magnic light output, it might have advantages over an all-steel or all-aluminum rim for some common uses.)

 

[conrad52]

...just tested now using a 6p (p-n-p-n-p-n) magnet, as soon as the rim rotates the 6p magnet rotates as well...

...and here below some follow-up:

THE NEW "ROTOR":

THE TEST SET-UP:

THE VIDEO:

 

[burt68]

With the Magnic Light generator being nothing more than a magnet-fitted rotor inside a coil (not a clawpole arrangement), I wondered if such a thing hasn't been made before. I've been looking around for a few days and actually found such a generator inside a Chinese-made LED shower head !

I opened the head to access the generator+LED assembly, took it out and removed its turbine cage, then stripped the turbine wheel.
Holding the little generator close to a spinning Al rim indeed does light the LED (!), see the video !

I have to admit, my wheel must spin at 40 km/h to light up the LED nicely, but then this generator device hasn't really been optimized for use as a bike light. However it works, and it has been there before the Magnic Light. Is there anyone deep enough into patent law as to say if this is then "prior art" and anyone can use this dynamo concept ?

The LED shower head cost me EUR 11.50 (bought in Germany). Now it's not just a generator-LED thing but a SEALED generator-LED thing plus a whole shower head too. Gives an indication of the cost we can expect when China mass-produces bike lights (or phone chargers, ..) based on this principle !

Thinking of what could be possible in the future, I imagine wheel sensors for wireless bike computers where the sensor is completely battery-free and works without a spoke magnet, detecting the wheel rpm through the rim joint. Another cool product would be bike computers with permanently backlit displays, the backlight powered by energy from the wheel sensor (wired one, in this case). And wireless shifting, where the generator assists a battery in the actuator-electronics, extending battery life dramatically....



To 2_i: My wheel's eyelets are ferromagnetic, but there's no noticeable force b/w magnets and eyelets if the wheel is stationary. So the eyelets shouldn't be a big contributor. And yes, the rim joint is noticable, but this only exists once per rotation and is not so pronounced that the light flickers much. So without being very scientific there, I feel that a wheel with no eyelets and no rim joint produces more or less the same amount of power. But of course, one has to test it to be very sure.
I perfectly agree, when you say that the progress in LED efficiency is a critical contributor to the success of this dynamo concept. The LED revolution has had a lot of impact in the last few years. It also made CPF grow tremendously.

I wonder if you could have put magnets in between the turbine blades ! .there are lots of water powered led lights on the net for kitchen taps and showers ,i wonder if Mr Magnic light has one on his bath tap and had a eureka moment

 

[burt68]

Well looks like it's real ,i was wrong to be skeptical and i am glad i was wrong.
http://www.magniclight.com/magniclight/index.php/en/startseite/8-magnic-light-homepage-english

 

[2_i]

I did not believe in the sufficient strength of Eddy effect either and was wrong. I wonder, thought, about the long-term future of Magnic Light, after the novelty aspect wears off. It has to be expensive, because the strong magnets are needed. It cannot be as efficient as hub dynamos - in my experimentation trying out the force on an alu strip, the strip was heating up quite a bit. Obviously over the rim it spreads out, but the substantial loss of energy to heat is there. It should be very convenient as a quick add-on on a bike without illumination provisions, but so is any battery operated light. The strong magnets may create problems in handling the Magnic Light outside of a bike. When I tried to mount my magnets in the N-N-N configuration, I had to use assistance of a second person and still cut my fingers so badly that they took 3 weeks to heal.

 

[Martin]

This type of dynamo is just perfect for certain applications where dynohubs don't fit:

1) Pedelec, front motor: The motor leaves no space for a dynohub, but German law requires an independent, dynamo-driven light system. Today, such bikes can only use traditional sidewall dynamos.

2) Travel bike: When riding during the rainy season, there's always some flooding of roads. Mud and water get into wheel bearings. They need to be opened up, cleaned and relubricated from time to time. Impossible with a dynohub. So it's either sidewall dynamo or Magnic Light.

3) Mobile device supply: A USB power bank enhanced with a Magnic Light generator. Attaches near the rim and charges the internal battery. Is removed after the ride and provides USB-power to charge phone or GPS. Any regular dynamo would be impossible to integrate into such a power bank. Flexible and scalable: Several power banks can be charged together. Can be put on front wheel or rear wheel.



I wonder how the power output of the Magnic Light compares to a Reelight SL-500.

 

[burt68]

found this
http://translate.google.co.uk/trans...a=X&ei=XgVnUZuHBYeZ0AXB-IHIBA&ved=0CDMQ7gEwAA

 

[Julian Holtz]

application for utility models

http://worldwide.espacenet.com/publ...cale=en_EP&CC=DE&NR=202011107060U1&KC=U1&ND=9

 

[write2dgray]

Hi Julez, good to see you here , we have overlapping interests.

 

[Savvas]

Hi Magnic-Light Fans ;-),

It may be a too-obvious question, but I would appreciate it if someone could tell me what the point of this new generator might be, or rather, what's the point of trying to develop it as a marketable product? I can see the novelty of exploring the eddy-current effect (if that's what it is). However I run dynamo hubs with what are now more-or-less conventional led lights and they seem to work exceptionally well with no drag worth mentioning and a capacity for light output that still has plenty of room it seems for further development. So what's the point of trying to make a generator that is potentially flimsy and easily damaged, will probably have to be adjusted 'just right' (we all know how easily things can get 'bumped' on a bike) and from what I can see involves a pretty basic light with an unshaped and inefficient beam?

I don't intend criticism - just trying to ask what I hope is a reasonable question, and remembering of course the fate of the rather nice 'LightSpin'...

Savvas

 

[Steve K]

hi Sam...
That's a fair question, and I don't know if there's an answer. I suppose the Magnic site would be the best source for what they thought their marketing advantage is. Myself.. I suppose I see these advantages:
1. goes on and off easy, so it's good for the fast bike or a bike that gets parked in public.
2. A single piece. No wiring. Similar to the old mono-block bottle dynamo. I had/have a couple, and liked it a lot. It also could be put on and off with just one bolt.
3. Minimal loss is the drive system. Not as good as a hub dynamo, but better than a bottle dynamo (I hope).

If it ends up being as cheap as the old mono-block bottle dynamo, then it could be a success. Otherwise??

 

[keys]

I think it can be better (cheaper?) than any dynamo but not in its current form. Some OEM should build the dynamo-function only into a front fork. I think retrofitting such a product is compromising its potential. I'm still a bit skeptical about power output though, but we'll see .