I've been using Ultimate Lithiums in my DR-44WL. Too many times I've found that one cell suddenly, it seems, drops to ~1v and the recorder shuts down. I could excuse a rare bad cell, but this has happened five or six times over maybe six months. I no longer trust them, so I've begun using an external USB supply and will probably revert to alkalines. Has anyone also found Energizer Ultimate Lithium AAs unreliable?