It's okay. When the battery box of the Bluetooth headset is charging, put the headset inside, and the battery box will also charge the headset, playing a role of transmission.
A Bluetooth headphone case holds two separate headphones, divided into the left ear and the right ear. It's all individually powered. When the headphones are charging in the battery compartment. Charge the battery first, and then charge the earphones. If you just charge the battery compartment, it will fill up. When there is no electricity to the headset, it can be put into the battery compartment for charging.