Wired the 4 wires at the bottom to a spare same amp fusible link on dual battery. VSR between batteries.
Worked very well as could leave key on and run radio, lights etc and never run start battery flat.
Because the VSR takes 15seconds to kick in and the voltage difference between the two batteries will the alternator be supplied low volts and then open voltage on the main battery. I was going to install a dual volt meter but haven't yet. I love having it like this so a interior light or anything makes no difference to being able to start the car.