I’m taking over your questions with quite a bit of delay…
The top layer surface is not made of aluminium anymore, we chosen ENIG instead which is more resistant to oxidation and corrosion.
The system detects what is the right polarity…"
"Interesting project! At Skysense (http://www.skysense.de) we developed a charging station for drones for professional use. We will shortly come up with a more convenient edition which price point will be around 100$."