Amazon.com: Synergy Digital Remote Control Battery, Works with Logitech Harmony 900 Pro Remote Control, (Li-Ion, 3.7V, 950 mAh) Ultra High Capacity Battery : Electronics
Amazon.com: Replacement for Logitech Harmony 900 Battery - Compatible with Logitech Universal Remote R-IG7 Battery (950mAh 3.7V Lithium-Ion) : Electronics
950mAh Li-ion Battery for Logitech Harmony 900, 190304-0004 – SMAVtronics
Logitech Harmony One Swollen Battery Removal - YouTube