Charging the charger and the Eargo devices
[With the Eargo devices inside the charger] Connect the smaller end of the micro USB cord to the white charging base, and the larger end of the cord to the USB plug. Plug the USB plug into a powered wall outlet. Place the charger, with lights and logo facing up, on top of the white charging base.
Make sure the charger is centered on the charging base. When the charger is properly seated on the charging base, a light on the charging base will briefly turn on, and you will hear a tone. On the charger itself, all indicator lights will briefly glow. When this happens, the charger (and the Eargo devices inside) will begin to charge via inductive charging.
Keywords: charger, charging, charging base, light, tone
Source: Charger Guide
User Guide Part #: LBL0025