AirCard 785S auto shut down

Hi community...

I bought this router because of its ability to start automatically, when power is being provided via USB. This works fine, but when I come back to my car several days later, the battery is always empty. The only options I can see (in the settings via browser and/or Android app) are "Display off" and "Automatic Wi-Fi standby" (translated from German, may be named a little different).  I can set this values (e.g. standby to 5 minutes) and this works fine (the display is off and Wi-Fi is in standby) - but this won't prevent the battery from running empty. Is there a possibility to automatic shut down the card completely after no Wi-Fi connection is used for specific time?

Best regards