You should be able to run everything in your trailer when your plugged in, you don't need batteries, your running through your converter. (if it's working)
Check your main grounds (frame and converter) and power connections at converter panel look for looseness, corrosion etc.
2018 Black Rock 24kts, 300 watts Solar, 4-230ah gc2’s
2008 Dodge 3500 4x4, 6.7 Cummins, full delete, 6 spd man. Firestone bags.