Yes, a wireless Bluetooth device does need batteries to function. Luckily for us, they are usually provided by the manufacturers. For example, most showerheads with Bluetooth speakers come equipped with batteries. All you need to do is charge it up before using it. Since these are built-in batteries, you don't have to worry about installing or replacing them. This further cuts down on maintenance costs. Such devices commonly use Lithium-ION batteries to power them.  The Bluetooth showerhead will be supplied with a basic USB cord. You can use this cord to charge the Bluetooth speaker. If there is no cord, you probably already own one or can purchase it easily from the market. The cord can be connected to a charging brick and plugged in. Alternatively, you can also connect it directly to your laptop to charge the speaker.