Love that dynamo! Your idea to hook it up to a bike makes me think of the old machines we used to have which were powered by pedals. I almost wrote a post about this a few months ago because back in the day it seems this was a very popular kind of machine. Perhaps, as is the way of the cycle, such ideas will become popular again with our current rise in electricity prices.
I would be very interested to see how you get on converting that bike!
Get your exercise and charge the battery at the same time. 😀