Last weekend the trams had their first real run and not unsurprisingly the fleischmann coupling proved it wasn't the one for my application, nothing wrong with the coupling it's just not what I need.
So some looking around and I found Piko do a similar coupling with electrical contacts, why didn't I find this coupling before was my first thought.
Roco also do a coupling with electrical contacts so a pair of both were ordered.
Bottom is the coupling I'm using just now and doesn't stay coupled.
Middle is the Piko one with electrical contacts, I suspect it could have similar problems staying coupled to the bottom one, but being slightly bigger I can tweak something to stop it un-coupling.
The top one needs to be forced to couple and is a real pig to uncouple, not really what I am looking for .
Using my simple electrical circuit I can get away with 2 wires between powered tram and trailer, so all trams will be fitted with the piko coupling and that has the added bonus of not needing to fit jumpers between trams.
Slowly this adventure is coming together.