The newer Lexon II , III and K2 have some impressive lumens now. They're still within the 3.3Vdc range and even the newest one will hold a steady 3.6V 350ma with bliding light output. With I'd say, a 20 degree beam, that green one I took a picture of will put a light on my ceiling 12 feet up and when using a defusser will cast a nice glow on my office.
Digital camera seems to have problems with some of the different light colors but I can certainly try taking more if you wish.

50Ah of NiCd? that's it, do I need to ship more;_)?

 I agree with the fact that the bigger, or more intergrated, you put on the RE the better the numbers look, but what fun is that?

Are you looking to use a dump controller in reverse to keep the LEDs lit?