This time I use these with 12 pins
In the Grünstern it is the 12 poles version from here:
https://www.bulgin.com/us/products/range/circular-power-connectors/400-series.html
plus a QS-8 for the main power lines.
The new one is much bigger (more than double the size, looks like a electric car charger connector in small) but it is capable for 10A in the 12pin version. This battery is so huge I’ll never need the expansion pack, which was the reason for the big QS-8 on Grünstern, so I can use one connector for charging this time 
The WF28 has a rubber cap but I’m planning to make a cap thats making use for the threads on the connector from the screw ring on the side (I’ll post pictures when I did that :))