For me it goes for about 1-1.5 hours, mostly I leave my PS4 in sleep mode, let it charge and then use it for the whole week without having to charge it.

Did you know how to solve the problem back then? I also bought the headphones today and the first bar has still been flashing for 2 hours. I'm starting to have the queasy feeling that something might be defective...

You must make sure that the bars "flash". The small headphone symbol lights up orange for me during the charging process. If it is red, they are not charging. You have to move the headphones back and forth a little on the charging station... unfortunately, this is not done optimally...