Lose time despite the integrated backup battery ... Definitely a shortage!

I ordered 2 pieces of this clock radio. Unfortunately, one of the devices for the first time has lost the time during the day after a few days - despite inserted fresh buffer batteries (2x AAA). This was then regularly again. Although it should have acted as a manufacturing defect - may indeed times - I have decided to return both units.

Because: An alarm clock must be reliable. So he comes in my opinion just as Radio in question.

Why still two stars? The radio works fine and the alarm clock looks nice.