Adding a battery

[Supervstech]

According to the following, 8mm2 is about 8 gauge, and 10mm2 is almost 4/0:

MyElectricalWorld - AWG To MM Conversion Guide

We Look At How to Work Out American & UK Cable Diameter Sizes, And Create a Handy Reference Table for Our International Customers to convert AWG To MM

my.electricalworld.com

Not quite correct.
107mm² in your post is 4/0 8.36mm² is 8, so 10mm² would be closer to 7awg...