I have used the Fenix L2D/L1D and 4sevens Quark Turbo (with single AA body) as helmet lights and have not noticed any rattles from the batteries. Of course, having it mounted on your helmet will keep the vibration damped so that might have something to do with it. If you are having a rattle problem with the light you have now, take a piece of paper and wrap the batteries so they fit in the tube tighter. That should stop the rattles from the tube.