Have been researching how to get USB charger from a hub dynamo such as the SON28. There are a number of options available albeit at some expense. I was really interested in the new Bush & Muller headlight with and integrated charger and cache battery. But after some research and re-thinking I have some doubts that is what I really want to do. First availability is unknown for the new headlight. Then I am not sure I need or want that awesome illumination. Further it only has a cache battery that is not useful for static charging devices when not riding.
I think what I want is to use the dynamo to run lights when needed and otherwise use the dynamo to maintain a battery pack that can be used to re-charge the Garmin 500, eneLoop AA – AAA batteries and a smartphone. To do this I need something like the LightCharge device which is about the least expensive alternative. Still need a battery pack like the Sanyo Mobile Booster.
The problem I have with the LightCharge device is I am not sure how robust it is and if it will handle the battery pack. I am inclined to do some experimenting and build my own dynamo USB charger. It should be fairly straight forward.
- a full wave bridge rectifier
- a 5v Voltage Regulator (Low Drop Out)
- heat sink
- three capacitors
Maybe $20.00 worth of parts (Ordered from Jameco parts for 2 devices $24.00)
Update found this article on this idea.