testing with multimeter
I’ve tested the ground areas with a multi meter,
The meter itself reads 0.4 – 0.8 ohm when touching itself.
The starting battery negative to it’s own ground reads 0.6 – 1.2 ohm (it’s slightly dirty)
The areas I want to connect the grounds of aux battery and switch as well as inverter read from 0.8 to 1.8 ohm from the starter battery negative.