A good rule of thumb could be the larger the speaker, the longer the battery life. But this isn’t always real, matters like much more updated Bluetooth firmware versions can tremendously effect power performance, and a large Bluetooth 4.0 speaker may not last as long as you’d assume relative https://www.bluetoothspeaker.top/bluetooth-white-noise-sleep-aid-music-player-rotary-button-red-blue-black-fabric-wireless-speaker/