I see an external USB plug for 5 volts-in to charge the batteries. The manual seems to say that the radio can be operated with this port powered.
Special note: Using the USB 5V cord to connect
the external power sources for supplying power
to play this radio.
The smart battery charger function can be toggled on or off. There is lengthy instructions and warnings about using chargeable and non-chargeable batteries.
Manual here: http://butik.limmared.nu/sv/index.php?controller=attachment&id_attachment=281