KC8QVO

Thanks for the thoughts. And yes, a ring of magnets around the wheel is what I had envisioned.

As to the voltage varying and the dynamo being a "current" source, you are correct. That is the exact same principal a wind turbine runs on.

I suppose I should ground my comment on "wind turbine" principal though. I am referring to small alternative energy systems that use battery banks to store energy, then run inverters to convert the battery power to AC power. In this case the wind turbine is pushing current in to the battery bank. The battery bank will govern the voltage, not the wind turbine.

The above having been said, in either the bike generator case I am thinking through or the wind turbine example, the voltage ability of the alternator has to be simply "higher" than that of the battery. With a protection diode to only allow current flow from the generator to the battery there will be no current flow until the voltage of the generator surpasses that of the battery.

It is like a bicycle tire pump. When you hook up the nozzle to the tire the pressure gauge will read the system pressure (tire and air hose up to the gauge). When you push on the pump you are overcoming the pressure of the system to put more pressure in. When you pull up on the handle to reset the pump the pressure doesn't leak out - it stays put because of a check valve. If you put light pressure on the handle and don't overcome the pressure already there - no air goes in to the tire.

When I came up with the 24mA yesterday - that was actual charge current pushing in to a battery that was under 13 volts (the SLA battery the dynamo is sitting next to on the table). For what it is worth, the voltage of the battery did increase so it was working - just the equivalent of a gnat fart compared to the draw of even just my cell phone charging.