I know this isn't scientifically accurate but here's what I did.
I just got a cateye EL500 and decided to compare the beam patterns of it against the lights I had with exposure lock. This was from about 10 ft away in a dark room.
I took the lights out and took some new pics here.
EL500 vs 5, 11, 16 watt halogen.
I think sign on the road is about 50 ft away.