According to the RC-20 specs, expected battery life under continuous use with alkaline batteries is 25 hours, qualified by: figures will vary depending on actual conditions. I have me doubts about that 25 hours. :-) I have never tried to run it on batteries til they drain. My experience with other types of pedal/fx is that the batteries usually tend to run out after about 4 hours. BobC The Thumb Piano Project www.mp3.com/thumbpianoproject http://trundlebox.iuma.com http://brokenaxe.iuma.com