Originally Posted by
JohnJ80
I’d agree with that.
They work well for lights only. Dynamos are at the limit of their capability for that since there isn’t much left over for charging They really don’t work all that well if you have even modest battery needs by today’s standards. There is no real room left to add more charging capability in the design of dynamos because it’s going to eat into your rolling resistance pretty significantly if charging were to go to, say, 20W which would be reasonable but that would likely require 30-35W at the cranks (which would be a problem). 20W would be pretty reasonable and would be enough to support a single 5V/1A plus a single 5V/2.4A USB ports.
I see dynamos as useful if you’re completely off grid and have no access to an outlet. I also see them as being overtaken by solar panels pretty quickly.
Just so you know, pretty well everything you've said here is not well informed.
The efficiency of conversion for most dynamo to USB chargers is now in the mid to high 90s percentage wise. So even if you did want to extract 20W it's not going to take 30-35W watts at the crank.
But 10W is what you'll get from a dyno hub at touring speeds, that's 2A. Over a days riding, if you have that going into a battery it's plenty to keep a phone going and have spare for other things. Over a 6 hour day of riding you'll get around 45-50WH into a battery and/or device. I can't imagine why you'd need 120WH a day when you're travelling.
Solar panels are pretty well useless touring unless you're in a desert or Antarctica because you're often in shade or not riding in the right orientation. Having once carried a fairly decent sized one it was ineffective for the room it took up. Also, the guys who we watched getting their panel, battery and gear stolen when they had to put it in a sunny spot slightly away from their campsite ( because you know, trees) probably don't think solar is such a good idea any more. By the time they jumped up to chase the homeless dude running off with their gear, he had way too much of a head start.