I'd like to comment on the polywire to metal connection.  If you look at premier 1 fencing terminal connectors they are flat clips that provide about 1 sq. Inch of surface area when connected.  You have to replicate something like this when connecting polywire to _anything_.  If you look at the charger connection it's not a point but a flat washer the wire gets compressed to.  I had success using flat copper tags soldered to copper wire to make pigtails to connect polywire perimeter fence to itself and the power source.