I found the owner's manual for the converter, with troubleshooting steps included.
https://www.hayseed.net/~jpk5lad/RV%20Information/MagnaTek%20Pwr%20Converter/RV%20Binder1.pdf
It has a diagram for testing the converter output, so I'll do that in a minute. I can't shut off the shore power without losing our Starlink, so I'm waiting for a better time.
I just tested my battery and the voltage is 13.8 when the converter is On, and 13.3 when the converter is Off. As I stood there with the multimeter attached, the voltage slowly dropped from 13.3 to 13.1 in about a minute, with the converter off, slowly losing voltage.
