Homemade charger?
 

Hey guys,

Just wondering if it is possible to make a charger hooked up to the pedals that charges your phone as you bike. I just got a smartphone and it dies really fast. I am planning a charity ride across the country this summer (check out my other posts!) and I don't want to be sitting at gas stations waiting for my phone to charge. Any links or photos, especially prototypes would be nice!

You can get a dynamo hub and a phone charger that runs off of that.
eg
http://www.peterwhitecycles.com/ewerk.asp

Generator hubs and devices like the E-Werk are becoming increasingly popular for jobs like that. Or solar chargers, for that matter.

I'd probably go with solar, if you can get a big enough one on top of your cargo. Lighter and doesn't cause any drag.

Drag is effectively a non-issue with modern genhubs. They're efficient enough that losses are equivalent to climbing a couple of extra feet over the course of a mile, and thus not even remotely noticeable.

The only downside of my relatively inexpensive Shimano genhub is a slight vibration between 17 and 19 MPH. Slower and faster than that, the vibration disappears. And I very, very rarely go at that speed when touring. ;-)

What is a dynamo hub? I was looking at the ewerk and don't really want to pay hundreds of dollars lol. Is there any way to make my own?

This is what my husband and I are going to attempt making when he gets a few days off. :) A mini-wind generator that I can put on the back of my rack. :)

http://www.instructables.com/id/Camping-Wind-Turbine/

Making your own would probably not be that big of a deal. I would *GUESS* that you need a largish capacitor and a boost/buck power regulator, those are pretty cake to design.

The dynamo hub is where the power comes from. You need a generator somewhere, people usually build them into the hub of the front wheel.

I'm honestly trying to figure out why - the video says that "The units on the voltmeter are in thousandths of volts and in this video the turbine creates over 1/3 of a volt." Later he says that at 1000 RPM he gets 1.6 volts - which would be just barely sufficient for charging a NiMH battery, but depending on how many milliamps it puts out, could take days to charge,

Plus, you might want to consider what the wind speed would have to be to have it rotating at 1000RPM...

Yep, there are a number of designs floating around. The advantage of the commercial products is typically in the packaging, since they generally offer a very small, waterproof enclosure that would be challenging to replicate without your own molding shop. ;-)

3D printer FTW. They're getting common. I've printed a few bike specific brackets and such. Enclosures are pretty easy.

I haven't seen any robust looking designs to DIY. From all reports, it's not an easy thing to design.

Building your own wheel with a dynohub isn't that difficult. I did it as my first wheel and it's going great!
As for the buffer battery, use the Motorola P893 available from Verizon stores. It has the ability to be charged AND provide power at the same time. It's also very small, light, and easily fits into some top tube bags.

I just got another brand/model to try out because it's rated at 2200mah and provides 5.5V at 1000mA, only costs $17 and is available at Best Buy. I'll post up about it in a different thread.