Installed the 500A/50mv shunt today. I didn't really plan for it when I installed the batteries so it was kinda kluged into place. I was also out of 0-gauge connectors so I had to make up a bus bar with two pieces of flattened 1/2" copper pipe. Still need to put a connector into the shunt sensor lines so it's easier to remove the board for s/w dev in the house rather than sitting outside in sub-zero weather with a notebook.
The main board is a TI CC3200 with WiFi. Here's a pic of what it looks like right now.
And a screen shot of the output that I can view in a browser.