I ended up deviating from the Aero Electric Connection drawings a bit and here is why. In my set up maybe yours the SD20 is a back up to the main alternator so only one should be operating at a time. You can put in two shunts and have two ammeters so you can see what each alternator puts out but only one should be making power at any given time.
My deal is Dynon 180 only supports one ammeter, now I could attach the two shunts to a switching system and I could toggle between the two shunts. I wanted to simplify things so this is what I did.
ANL protects main alternator B lead, Standby will be protected with a fusible link and attachs to the down stream side of the main ANL, this way if the main ANL blows, Standby can pick up the load. The shunt is down stream of them all so I will read on my single ammeter the power going to the main bus and battery from whatever is providing the power. I am also not using the hall effect sensor with the SD20, I have a load shed plan that I know will keep me at about 10 amps which should work. Note that the SD20 is only 20 amps at cruise RPM when you reduce power your load may start to lean on the battery.
I ran this by Bob Nuckoles and he said it would work, don't think he thought it was something he would publish though.
