Since mr.jb.swes project Multicharger is all over my feed, hackaday.com (congrats!) and this page too, I'm thinking far ahead of my timeline. To keep it simple I want a single cell setup, boosting the voltage up to 5V. The hall effect sensors are only working with 5V so I started my first compromise, which turned out to be good, because this way I can monitor the power from the cell with an analog in pin of the arduino and everything gets more tinkerer-friendly. Now I need a way to get the dynamo voltages down to 3.5V to charge the LiFePo accordingly. Sounds overly complicated to convert from 6V to 3.5V to 5V but a battery comes in handy when you are standing because of a traffic light in the nights and you don't want your lights (or computer) to go off.