Il problema dell'alimentazione elettrica per chi usa la bicicletta, sia nell'uso quotidiano che per viaggi di più giorni, sta diventando sempre più impegnativo. Serve sempre più energia elettrica non solo per illuminare la strada nelle buie ore della notte ma anche per alimentare il sempre crescente numero di dispositivi elettronici a cui non sappiamo più rinunciare. Questo sito vuole essere un primo passo per provare ad orientarsi nella non sempre facile scelta degli strumenti necessari per gestire in modo possibilmente autonomo le proprie necessità.

The electric power supply problem for people who like to cycle either in everyday use and along trips of several days, it's becoming increasingly challenging. More and more electricity is indeed required not only to illuminate the road in the dark hours of the night but also to feed the ever growing number of electronic devices that we can't live without. This site aims to be just a first step in the attempt to orientate the user in the not always easy commitment to choose the most appropriate tools.

Tuesday, 12 November 2019

Dynamo Eddy Currents

Talking about “eddies” I think that they are exactly the same either at lights-on or off. Eddy currents indeed entirely belong to the magnetic circuit and arise due to the reciprocal interaction existing between moving magnets and the steady laminations steel. 
Lights-off dragging is basically due to mechanical losses and core or iron losses, they in turn being composed of eddy and hysteresis losses. 
To arrive to lights-on dragging you must add: 

 1. Copper losses that for a 3.5 Ohm coil of a hub dynamo at 0.5 A account for an additional 0.9 W approx (based on a nominal 3 W output, i.e. 6V-500mA) 

 2. Actual active output power delivered to lights, or whatsoever connected load. 

So I can’t understand how is possible to have lights-off dragging bigger than lights-on dragging ( ? )