Originally Posted by
RomansFiveEight
My other thought, was to mount a USB-chargeable battery in line with the generator. I.E., one of those smaller battery paks, that can charge from a USB source (as opposed to a 110V source), attached to one of these generators. And then the external battery, attached to my iPhone. My thought process is, the external battery pak becomes a buffer. And prevents the issue of potentially charging starting and stopping as I start and stop (or even slow down to a point potentially too slow for the generator to work).
There's a few out there that don't work well, and some that do. I hear good things about sinewave. It will deliver 5W from a dynamo hub. Yes charging a battery pack is the safest bet. You can also get battery packs that will charge while powering your device at the same time (a lot don't do this).
Sinewave Cycles Revolution | Sinewave Cycles