I think it is time to update this speaker with a 3S2P battery pack for a voltage of about 11.1v which should give it the longevity it deserves. The upper voltage would be 12.6v while the low voltage would be 6v.

Power Consumption

Idle	19 mA
Running	260 mA

Bluetooth Module

【Upgraded Bluetooth Adapter】: High Bluetooth V5.0 makes your non-Bluetooth devices Bluetooth-Enabled, easily transmit audio wirelessly. It's compatible with a variety of Bluetooth devices.
【Low Delay】: With aptX lantency technology, this adapter provides fast, stable and smooth transmision without audio delay. You will get a rich and clear sound experience and enjoy comfortable audio-video synchronization.
【2-in-1 Function】: Transmitter Mode: Plug into your non-Bluetooth device like TV, PC, CD player, MP3/MP4 and pair to your Bluetooth speakers and headphones. Receiver Mode: Plug into your non-Bluetooth Home/Vehicle Sound Systems and pair to your smart phone.
【Plug & Play】: Mini Bluetooth adapter, no need any drivers, plug in the USB port to use. One-button switching mode, red light for transmitting mode, blue light for receiver mode.
【USB Power Supply】: Charge it on the USB port, never worry about running out of power when you use it. Enjoy 1 year warranty.