I have 2 matrice 300 battery station, we havent flown for a while, do the stations automatically discharge and recharge the battires?  Or do I need to power off and power on the battery again ?

Hi there, thank you for reaching out. You could follow the following path [UAV Health Management System] - [Battery Station Mgmt] - [Self-Discharge Settings], to charge or discharge the battery to 40% ~ 60% if NOT intended to be used for 10 days or more.

This can greatly extend the battery's overall life span. It takes approximately 6 days to discharge the battery to 60%. It is normal that you may feel moderate heat emitting from the battery during the discharge process. You can set the discharging thresholds in the DJI Pilot app.

Notes: For safety reasons, in firmware v4 and later versions, if the product is not used within 12 hours of being fully charged, the battery level will be discharged from full battery level to 95%.