Volvo V70I battery constantly empty

Hello together, for some time now I have the problem that with my V70I TDI (automatic) the battery is constantly empty, although I drive 70km daily. During the week it is mostly just like this, but at the weekend the power is constantly empty – then only foreign start or charge with charger helps. The battery is about 3 years old, the alternator is about 1 year – I exclude these two things from the troubleshooting. Mass pole terminal on the battery I have renewed. Connections at the The battery and the starter are cleaned. After replacing the pole clamp, I thought the problem was fixed, as well as after cleaning contacts. What else can it be that I am constantly running out of juice? I read something about a central locking problem in older Volvos, can this occur with the V70I as well? I am grateful for every tip. Greeting, Anton