As with any battery powered device the batteries will eventually become discharged. Different use cases will cause the batteries to drain faster such as listening to music at high volume or using the display’s backlight at its full brightness for extended periods of time. We advise our customers to set the display at the lowest brightness to prolong the life of the batteries. To do this, press the HOUR/DISPLAY button while the radio is off to set the display brightness. This will set the brightness of the clock while the radio is on but not in use. Alternatively, you can purchase an AC adapter from Eton Corporation by calling 1-800-872-2228.