Originally Posted by
Mark Hoaglund
Aren't dynamo hubs in the 6 volt, 1.5 to 3.0 watt range? Whats a good one for charging phones? Do LBS charge much to install one?
It is complicated, I will try to be brief.
Yes, dynohubs are in the 6v 3 watt range, but it is an alternator, fast downhills can push that higher. And if you are not using much power, the voltage can climb quite high. It produces alternating current of variable voltage and amperage depending on speed and how much current is being drawn out of it. It is not like a car alternator that has a voltage regulator, there is no regulator.
Son, SP and Shimano are the common ones.
You also need a USB charger than can convert the alternating current to direct current of a nearly constant 5 v. There are several out there, I mostly use a Sinewave Revolution. There are a couple that are also combined with headlights.
Some phones and other electronic devices are quite picky about their power supply. While you can directly plug some phones into a USB charger on a dynohub, some phones and other devices require a pass through cache batter (or buffer battery) to keep the voltage and amperage more steady when you speed up, slow down, occasionally stop, etc. Some USB chargers include such a battery, some do not.
Some people use a dynohub and USB charger to put power in a powerbank while rolling, then later in the campsite plug their phone or whatever into the powerbank to charge it. That can be the simplest way to do it.
It is most cost effective to include a dynohub in a newly built bike. Adding a dynohub later costs a lot more.