First Top Charge

Well, if the shunt is a 500 amper with two 3/8" bolts, it should be wired with no less than 4ga; but I recommend 2ga after seeing the difference it made on mine. And if the mega watt can't handle the large wire, the OP can do as I did, and modify a couple of heavy duty 5/16" ring terminals to fit in the power supply's screw connectors. Just hacksaw off all but a piece about 3/16" wide by 3/4" long, and stick it in the terminal and tighten down good and solid. I hooked up my pm4b-45 this way. And if the power supply is mounted to some wood, the wires can be stress relieved by simply clamping the wires down with wire clamps.

http://www.victronenergy.com/upload/documents/Datasheet-Battery-monitoring-EN.pdf

http://www.ebay.ca/itm/Quick-Cable-Starter-Ground-Lugs-1-2-ga-5-16-Eye-p-n-6401E/251699406837?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140620075055%26meid%3D12f246ee4e7045f99fab57cf970a91ec%26pid%3D100011%26prg%3D20140620075055%26rk%3D1%26rkt%3D10%26sd%3D251664140661

http://www.elecdirect.com/catalog/cable-clamps-p-clips/steel-clamps-w-vinyl-cushion