Magnic Light claims new form of no-contact bicycle dynamo lighting
By Ben Coxworth
February 16, 2012
Despite the continuous advances being made in lithium-ion battery technology, many cyclists still prefer to use dynamo-powered lights on their bikes - there's no having to remember to recharge the batteries, no subsequent forgetting to put the light back on the bike, and no worrying about the batteries unexpectedly giving out mid-ride. Dynamos, however, have their own drawbacks. Friction-powered sidewall units slow the bike down and wear out the tire, while dynamo hubs must be built into the wheel, and add to the bike's revolving weight. Now, however, German inventor Dirk Strothmann has created what he claims is a better alternative - a small, no-contact, self-contained dynamo bike light.
According to Strothmann, his fork- or brake caliper-mounted Magnic Light works with any type of metallic wheel rims. While other contactless dynamos do exist, those incorporate wheel-mounted magnets. Dirk's product, however, has the magnets in the dynamo, and utilizes eddy currents. In a nutshell, these are electrical currents that are induced in a conductor, when that conductor is exposed to a changing magnetic field.
"Relative movements of magnets and neighbored conductive material induce eddy currents in the conductive material - in our case the metallic rim," Dirk explains on his Kickstarter fund-raising site. "These eddy currents have their own magnetic fields which are absorbed by the Magnic Light generator kernel and by this way produce electric energy."
This phenomenon apparently even works with aluminum and magnesium rims, as the rim material only needs to be conductive, not magnetic. He states that there is a slight braking effect on the wheel, but that it is less pronounced than that caused by traditional sidewall dynamos. As can be seen in his pitch video below, the light output does appear to warble slightly, in time with the spinning of the wheel.
The light itself is produced by dual CREE LEDs, which at approximately 16 mph (26 km/h) are said to kick out a respectable 150 lumens. In its present prototype state, the Magnic Light simply turns off when the wheel stops turning. If there's sufficient consumer interest, however, a future version might include a capacitor to keep the bulbs burning while the bicycle is stopped.
It all perhaps sounds a little fishy, but Strothmann says that the public can come check the system out for themselves, when his light is on display at the FAHRRAD bicycle trade show in Essen, Germany, from February 24th to 26th - potential investors might want to wait until after then before sending in their money!
For people who are interested in funding the project, a pledge of US$199 will get them a front and rear light, when and if the funding goal is reached, and the light goes into production. A pledge of $130 will get them a front light only.