I've never known a DAB radio to eat batteries at the rate this one does.
Four fully charged rechargable AA batteries didn't last 24 hours despite my only listening to the radio for an hour or so before bed and the unit being on 'standby' (only displaying date and time) until the morning. When I checked later in the day, the batteries were exhausted and I've had to put them back on charge again.
It seems the unit will only function properly while attached to a mains electricity supply.