I have a 1 Battery D-Cell adapter for Older Arc-LS's that can run on a 1.5 volt power source. I have never done a run down test for it. I wonder how much shorter an old Arc-LS would run compared to an Arc-AAA. But I would rather know how low a they will both pull a battery down. If they both pull the battery down to .9 volt, I will just Use the LS-Holder. If the Arc-AAA head will pull it down further yet, I might be inteersted in a D-Cell Arc-AAA