Have been riding with a Shimano hub generator and the B&M Luxos U charging 3 X AA eneloop batteries. At the end of a 35 mile ride the batteries are charged and then I can recharge the Garmin 500 using the PortaPow.
The Garmin 500 will only charge to 99%.
While touring will take 5 X AA , 2 in the GPS, 3 in charger. Also 3 X AAA in the the head lamp along with three AAA to AA adapters. Will also take a USB A to micro USB and USB A to mini USB cords. Will not be taking the Garmin 500.
While riding I will probably keep the Garmin Vista turned off.