Amazon.com: FITHOOD Replacement Battery for LOGITECH MX-880 MX-890 Harmony One F12440023 NTA2340 One Harmony 900 Harmony 880 Harmony 890 Harmony 720 R-IG7 Harmony 900 Remote : Electronics
Amazon.com: Synergy Digital Remote Control Battery, Compatible with Logitech Harmony One Remote Control, (Li-Ion, 3.7V, 950 mAh) Ultra High Capacity Battery : Electronics
Amazon.com: Logitech Li-ion Battery for Harmony Remote ONE 880 890 720 : Electronics
My mouse works with only one battery. It's been over a year. : r/mildlyinteresting
Logitech Replacement Harmony One Remote Battery Door Cover
Harmony Ultimate One Battery - Logitech Harmony Ultimate One Battery - Spare Module Type Logitech Harmony Ultimate One Replacement Lithium Ion (Li-Ion) Remote Control Battery – CutRateBatteries.com
UltraLast Rechargable Lithium-Ion Replacement Battery for Logitech Harmony 1000 Remote Control URC-LOG1000 - Best Buy