There are many fancy battery powered Bluetooth speakers on the market. Not all of them are loud enough for every occasion. The SoundBoks 2 is a 122dB Bluetooth speaker that runs for 40 hours on a full charge. It has a shockproof case and weighs 33lbs, so you can move it around without breaking your back.
The SoundBoks 2 measures 26 x 17 x 13 inches. It comes with a military grade battery.