I got a 12.5 watt dual beam job that runs 6.2 on flood and 6.3 on spot and with both beams on it would burn continously for 2.5 hours or 5 hours on one. I use the flood only for commuting then when I head for the pitch dark bike path I use both for extra safety though even then one is enough, either way I cannot out ride the light even at 42mph (that's not my average in case any of you are wondering). The 6-D battery pack attaches to the frame and can get those D bats anywhere and I'm not tied to a wall. The cost was only $45 and the unit is a Cygo Metro.