What is the best way to maintain the charging contacts of the charging station and the robotic lawnmower?

It is best to clean the charging contacts of the robotic lawnmower and the charging station with fine sandpaper or steel wool. Then wet the charging contacts with a contact spray or commercially available machine or lubricating oil/grease (e.g. battery grease). The aim of this measure is to protect the charging contacts even better against environmental influences (corrosion).