question

Hi @Adam Martin

There are a few mistakes with your diagram.

I have done a rough correction,

1) you had the shunt the wrong way around - this picture makes it clearer which terminal needs to be connected to the battery (the one closes to the VBatt+ socket, and which to the system (loads/charger) (the one closes to the VE.Direct port).

This wouldn't have caused any damage but the count would be backwards.

2)

You had the Aux connection connected to the battery negative of the starter battery. Now I am presuming that you want to use this as the 2nd battery voltage monitor, like in this example;

So it needs to be connected to the positive terminal.

3) You also had the positive Vbatt+ connected to the positive of the 2nd battery, this should be connected to the positive of the main battery that you wish to monitor state of charge (your lithium battery).

I've made a few assumptions in there so I could be wrong, but this is how I think your system should be wired;