On 11/27/2011 1:03 PM, Ian Field wrote:
"John wrote in message
...
On Sun, 27 Nov 2011 14:56:00 -0000, "Ian Field"
wrote:

Tinkering with the old Sturmey archer bicycle dynamo, I was wondering
whether it would charge a 1.2Ah SLA any better if the loading was
modified.

The generator is rated 6V/3W, but off load at a decent rate of knots it
can
produce over a couple of hundred volts.

What I was wondering was whether its possible to get more energy into the
battery by letting the generator output voltage stretch its legs so to
speak
and convert the excessive voltage down with a buck converter.

I just saw a piece on tv about a health club that has all exercise
bikes fitted with a generator. They are all wired to a panel that has an
inverter. The energy is used in the healthclub. They have a display on
the wall showing current watts being produced. At one point it showed
2,400 watts, later I saw about 1,300 watts.
I suspect their payback will be long.
Mikek