I run a hyd winch on the front and a warn 15000lb on the rear via a big 200a/h battery, so the second unit is set up to pump the juice into the winch, plus my coffee machine! I run the driving light circuit off it as well as the LED bars run at 30V. The alternator supplied as standard with the Chev conversion is rated at 100a, and it struggles with voltage supply also - constant winge to brunswick diesels hasn't fixed the issue, so i went the second unit as it means I don't need to upgrade wiring for the existing circuits as well.
There is a 170a unit avail, @
MB has one fitted and it works well, but still requires some mods to fit. Lastly it also gives me some redundancy if one alternator fails - and yes it has happened to me on a trip, middle of winter, back of Omeo and miles from nowhere, very uncomfortable feeling, especially when some of the drive home would be in the dark.