For the tinkerers and DIY crowd...

[2dumb4gears]

I've been running a Shimano dynamo hub on my Crosscheck and have been super-psyched on it. I know of people doing things like rigging a capacitor with a 9v battery to store a charge. Has anyone ever thought of (or better yet, figured out how to) charge a cell phone, GPS, etc. off of a dynamo hub? I'm thinking about a 2 week tour later in the summer, and it would be awesome to charge as I ride.

[tryandgetme]

at 6 volts and 3 watts (which is 500mA), it'll be close, but it'll probably charge it if you keep the backlight off and don't do anything with it. You'll need a 5 volt voltage regulator though (assuming your phone trickle charges on 5 volts). This would probably work: http://www.solarbotics.com/products/index.php?search_id=114 though you should throw an ammeter between your phone and it's charger to make sure it's not going to draw more than 500mA. I made a car charger for my phone that's current limiting to 500mA (though it was 13.5v, 6.75 watts) , and it charges it fine, so you're probably fine with the LM2937-5.

You'll need one monster capacitor to keep that charge rate up when you stop, a better choice might be to go to an RC airplane shop and get a 4 cell (6v) 250mA nicad battery pack (small, fast to charge), and have that run the voltage regulator and the cellphone, while the dynamo charges the battery pack.

[rockhound]

I've been intrigued by this Dynamo hub as well.

Another alternative would be those flexible solar cells that Maurice or Shannon posted a month or so ago, especially if you are going to pull a trailer.

[myron]

.....you could also use that dynamo to charge a points capacitor. You know,30k volts right in the gooch. Just dont forget to disarm before you ride it.

[2dumb4gears]

I thought about the solar option, but the good ones (like the Brunton mats) run around $400; the lesser ones don't work as well, or charge a battery and then require you to trickle-charge to your device. I figure since I already have the hub (and don't really need the light on during the day), it might be worth the jury-rig.

[Family Guy]

I've been eying this thing:

Looks like it should do the trick, and only 8 oz.

http://www.rei.com/product/744355

http://www.rei.com/product/744355

[2dumb4gears]

I want something that specifically will run off of my hub. Just found this guy, though they've yet to post prices/distribution info:

http://www.copycatsolar.com/index_files/Page504.htm

[Spalls]

2dumb:

Do you have any electrical engineer friends who work at Boeing? These guys are a great resource and great tinkerers. My friend Jon builds his own power packs and battery chargers, he was building LED flashlights years ago, and he is currently in the process of rigging his house for power from a diesel engine running on used cooking oil from the Boeing cafeteria - he will run the extra power back into the grid and get a check for his efforts (legal since last year). Use your local resources!

[2dumb4gears]

Actually, I do have a couple of friends at Boeing. Unfortunately, one is a management consultant, and the other is a mechanical engineer. I might just pick up an "electricity for dummies" type of book this weekend, and see what I can't rig. I don't think there will be too much to it, since the dynamo hub is already there as a source and regulates its own power output.

...Of course, you could put me in touch with your buddy...and we really should ride together sometime.

[tryandgetme]

http://www.eidusa.com/KITS/7805_SCH_001.jpg

simple 5v voltage regulator using two capacitors and an LM7805. add in a simple small 6v battery pack on the source side, and you've got a simple charger.

Edit: oops, sorry the 7805 takes a 7v minimum input.