On a Damon typically, the Intellitec Battery Control Center (BCC) does not send juice from the shore-power (via the converter/charger) to the chassis battery.
This is to protect the unused/parked chassis battery from the surging charge loads provided by the converter as you use the RV's 12VDC systems...which could cook the chassis battery.
Some models or owner modifications had an additional unit called an Intellitec "BIRD" (Bi-Directional Isolator Relay Delay) that had that function. The BIRD will control the juice to the both the chassis battery (to prevent cooking it) and house battery, charging from the engine alternator.
If an owner did not want to use the Intellitec BIRD, they could opt for a different brand device like a Trik-L-Start or similar. They do the same thing, but independent of the BCC...and being separate, it is not impacted by the salesman switch (battery cut-off). see:
Ultra TRIK-L-START Starting Battery Charger/Maintainer
Best luck