Fibaro door/windows sensor 2 draining battery

I’m new to smartthings and z-wav. But I got my smartthingshub and some light bulbs and now I added two fibaro door/window sensor 2. Smartthings founded the sensors but I had tochange the device handler to be a door/window sensor. Then the devices worked correctly. I installed both these sensors on friday 19 januari. Yesterday I saw that the battery on one of the sensor was 70%. And today it was 50%. So in less then 48 hours the battery has drained down to 50%. The other sensor is still on 100%?

Does anyone have some ideas why I have this problem? And is there anything I can do?

Ah I see. Thanks. I Will relax then and see if it slows down.