Does the extra battery have Bluetooth in it?

The additional B2 batteries do not include Bluetooth modules. Instead, their data is transmitted to the app through the host power station. For example, if you purchase a Mega 3 and two B2 batteries, the Mega 3 collects data from both the B2 batteries and its own system, then uploads it to the app via its built-in Bluetooth module over the parallel connection. B5 batteries also share this feature, relying on the host station for Bluetooth communication.