Battery automatically recharges during mains operation and then stops in the display is off and volume about three-quarters of the maximum long time through. Approximately 12 sins continuous operation I've done, the display then showed indeed "battery low", but the machine was still running.
Recommended for those who do not want to run from outlet to outlet. For Internet radios, which are moved, very practical, because these devices usually lengthy boot after each change of location.
