Originally Posted by
RomansFiveEight
The OP just wants to learn. I'm curious, new to this, and intrigued by the prospect of charging devices while riding. The reality is, an external battery pak is all I can imagine I'll ever need. But I was intrigued when I saw those and thought "I wonder how well those would work if I rigged something up like that".
When I mentioned a dedicated bike computer; I was referring to something like a Garmin 810. Something that will record rides, offer routing, keep track of altitude, distance, speed, etc. And log everything nicely. Although that's all down the road. My iPhone will do most of that anyway, for now.
I actually did find a few cheapie bottle dynamos that reviews said (slowly) charged smartphones, or at least staved off battery loss. Although it seems like more trouble than it's worth; I think it's a cool concept. Which is why I asked! That way I might learn something.
Yeah, you can get a dynamo hub that will produce electricity. It's output is fairly limited - it can charge a phone no problem, but some tablets require to much power.
Usually dynamo's are used for generating power for a bike light at night, if you spend all the money on a dynamo I'd also buy a light to go with it. 15 years ago dynamo light was crap, but then they invented LED's which required far less power and made shaped-beam lights which use the light efficiently (among a number of other things).
Ixon Iq Premium - good light, $110 or so.
Schmidt Edelux II - same light at the iq premium, but slightly brighter and with an led with a nicer color temperature.
Luxos U - both a light and has a built in usb charger. Can only realistically run one or the other, but it's all in one unit. Drawbacks are it's size (it's kinda huge), some people feel it has a slightly worse beam pattern than the previous 2 lights, and it's expensive, though the cost is the same as buying a light + charger accesory.
I mean it all gets pretty expensive, an external battery pack is much cheaper. I have a dynamo light though because the freedom of always have a light on my bike and never ever worrying about headlight battery life was worth it for me.