"Tom Del Rosso" wrote in message
...

John Larkin wrote:

How many switches do you want? What do they do?

The bike dynamos I've seen have a mechanical disconnect that moves it away
from the wheel, so you don't need a switch on that. Just one on the
lights.

The original topic relates specifically to hub 'dynamo'.

Rubwheel 'dynamos' have huge drag when engaged and obviously won't be
topping off the battery when disengaged.