Troubleshooting a Balmar 621 for my dad

[autumnbreeze27]

My dad’s boat has a Balmar 621-100-sr-ig
I’m pretty sure when we surveyed his boat we checked that the engine charged the battery, so at some point the alternator has stopped working.

I figured he had a switch wrong on the panel and fried it.
I traced the panel and it looks like the alternator should have had a path to the house batteries at all times.

I tried to find the controller but could not locate it. Is it possible to run these alternators without a controller? Is there any way to troubleshoot it or just bring it to an alternator shop?

Found this:
http://www.balmar.net/PDF/Alternator%20Manual.pdf

[DeepFrz]

The Balmar 6 series (621 etc) have internal regulators but can be regulated externally is desired.

How much current is the alternator putting out?
Are the batteries being charged by a shore power battery charger? If so turn off the shore powered charger and discharge the batteries some by turning on lights etc. for 15 minutes or so. Then start the engine and see what kind of current the alternator supplies to the batteries.

[autumnbreeze27]

It's not outputting any power. Turned the charger off, watch the heart 2000 display and the voltage just drops and drops.