motownrockwrote a review of Serfas SL-ONE Headlight - 1 Watt on February 23, 2011
In flashing mode you're clearly visible to cross traffic that may pull in front of you, or oncoming traffic that may be turning left. However, in the steady mode, this is not bright enough to illuminate your ride at any reasonable speed. Steady mode is more of a back-up system in case you're main light dies before you get home. Per willhuff's comment about the rapid decline after 15 hours, that's probably more a function of the battery type than the light. Without going too far off topic, traditional alkaline batteries tend to fade steadily over time, but some rechargables are more prone to deliver almost full power until they're spent, then they die out quickly. Either way, I like the fact that this uses standard batteries that can be replaced at a drugstore or gas station in a pinch.