The universal microphone receiver can be charged while in use or while off, depending on the design and functionality of the device.
Some universal microphone receivers can be plugged directly into a charger or USB port while in use to charge while continuing to work. Other devices may need to be turned off or put into standby mode before charging. In addition, some universal microphone receivers are also equipped with wireless charging, which requires no cable to be plugged in after being placed on the charger. In short, the charging method may vary from device to device, and the user should operate the charging correctly according to the device manual or relevant instructions.
It is recommended to charge the battery when it is turned off to protect the battery.