It's been fascinating watching this whole project develop. If you don't mind, when you are all done, would give me an idea what it cost, assuming you don't charge for your time?

The reason I ask is that I just bought a NiteRider 7.2W halogen light as a closeout from Nashbar for $30. It was intended to run on 4 C-cells but I substituted a $10 Powersonic 2.9 amp-hour, 6V SLA battery. So for $40 I have an adequately bright rechargable light. Did your project approach that cost?