Regarding hub dynos: Think about an e-bike, the thrust it provides, the time duration, and the battery size; Charging a similar battery size, over the same time duration, would impose about the same thrust in *drag* on the bike, an insurmountable amount on a manual bike. Half the battery, half the drag, but that's still a lot. Even a quarter the drag. I think a hub dyno *might* be able to keep up with the drain rate on a smallish phone or nav device, a constant display on bright is the biggest draw on that.

For my anticipated need of a multiday battery to power my CPAP, a hub dyno is not enough, and that's with running the CPAP with no humidifier (uses heat) or tube heat, as those both suck more E than just the blower motor. So my plan will be to 115VAC charge the battery every couple of days. Leaving it plugged in overnight at a campground bathroom is too susceptible to theft. I'm hoping to map out public libraries, coffeeshops, etc, to fast charge the battery, hopefully with multiple AC plug inputs. Or find people via that org that I forget, for scheduled backyard camping, with charging at an outside plug.