I am replacing a diode isolator with a Victron fet isolator. I have a duvac alternator on the coach and from the directions, can't figure out if I leave the alternator wired like it is and install the Victron as a direct replacement. There is a place on the Victron to hook up an ignition hot and a ground wire to another place. Any help would be greatly appreciated. Thanks Ron
Ron,
You can leave your DUVAC alternator hooked up (excite wire and sense wire) just as it is. The alternator will still adjust its output to "see" the proper charging voltage on the sense wire from the start battery. The only difference is that because there is no voltage loss between the ALT post and the ENG BAT post on the ArgoFET isolator, the alternator will be able to reduce its voltage output slightly compared to what it was putting out with the old diode isolator.
The GND terminal on the Victron isolator should be connected to a good chassis ground.
The IGN (energize) terminal on the Victron isolator is only needed if you swap from a DUVAC alternator over to a Delco alternator. If curious, see Peter's post linked below with links to his explanation of this subject.
Delco Remy replace for LN A0012670LC (https://www.foreforums.com/index.php?topic=40170.msg397594#msg397594)
Thank you for the help. I plan to install it tomorrow. I had to replace the battery ground and positive cables to the starter and boost solenoid. They had gotten hot at sometime and the insulation was coming off. Also had to replace the boost solenoid as the nut holding the battery cable was loose, tried to tighten and it was stripped. Major job trying to get it off. It was not moving on or off, only turning. This slowed down the process of getting the Victron installed.