I went for a nice, chilly (32F) early morning - starting out dark - ride this am.
I have installed two 53 LED lights on my bike, and they are bright.
I remember when I was using Vista nightsticks for a while. Big, heavy, bulky batteries, always having problems with them, mediocre light, etc.
These babies operate on 3 AA - I use rechargeables - but any AA will work. They are located right inside the light.
And - just $8.95 each (plus shipping) - see:
The downside. They are pretty cheaply made, you have to devise your own shim to get them to attach correctly and tightly to your bars (I used a piece of rubber from an old 700 tube), and you need to really tighten (and keep tightening) the single mounting knob. Also, rechargeable batteries vary in quality. I find the Radio Shack last a long time. Also, a jolt (like a curb) will cause the light to jiggle down just a bit - on the other hand, you can also adjust them up and down fairly easily.
BUT, all in all, they work great. Very bright. I get 2-3 hours from one charge, and I put them on blink when it is light enough for me to see, but I still want to be seen, and they last a loonngg time. If I need longer, I just put 3 small AA batteries in my pocket, and they are replaced easily. Plus, the light disconnects from the mounting bracket easily, so one could also use it to change a tire. If needed, one could operate very well on just one light, then switch to the other as the first one dimmed out - giving 4-6 hours of light.
It is always difficult to show how lights work in a photograph, but here goes. For the camera, the two lights blend into one, but actually one sees two lights.