So a little update
Thanks to frank and andy (enuo) pointing out the obvious to me last night that my 80amp fuse was surviving 150+ amp cold crank amperage there's something not quite right
Sometimes the hardest things to spot are the most obvious
So I set about this morning testing my wiring and my set up
Battery came out @: 12.45v which isn't bad considering it hardly ever gets used
Then I tested the cca of my starter which came out at a measly 59/60amps. Starter turns over like the battery is almost flat. Which I assumed it was so thought nothing more
No picture here its hard enough holding the two multimeter prongs
Traced all wires and the starter isn't getting the full 12.45v from the battery.
I changed some terminals over tightened some connection and cleaned up others.
Tested the starter this time and a full 12.45v at the starter.
Engine start button pressed pop went the fuse.
Now defused my battery wire and it cranks over sweet...
I guess we call that problem solved 
