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
Logitech Harmony One Swollen Battery Removal - YouTube
950mAh R-IG7 LOH880 Remote Control Battery and LED Charger for Logitech Harmony One, 900, 720, 850, 880, 885, 890 Pro, H880 - AliExpress