When you say they don't work wired together 'so much', is that not much when you turn the wheel with your hand, or not much actually riding at 10mph minimum for a minute? Could it perhaps be something like the light capacitor need charging, if you haven't ridden it down the road properly yet? If not, I am no help, never used a power pack thingy.
I don't think the D1 needs switching. It will dim your light when charging so I charge a battery pack during the day and unplug stuff from D1 at night.
When you say they don't work wired together 'so much', is that not much when you turn the wheel with your hand, or not much actually riding at 10mph minimum for a minute? Could it perhaps be something like the light capacitor need charging, if you haven't ridden it down the road properly yet? If not, I am no help, never used a power pack thingy.