You state you are naïve about RV electrical systems. So, why would you state it seems wrong that Winne runs the slides from the Coach Batteries(Long Story)? MOST RV makers state to have the coach plugged into 120 or have the Genset running when operating the slide rooms. This is to make sure you have FULL 12 volt power to the slide room mechanism system. That means you will have either the Power Converter or Inverter/Charger(which ever you have) helping to get the full available power to operate the slide rooms. MOST Motorhome makers use the Coach Batteries to power the slide rooms. When plugged in and the Chassis engine running, BOTH are charging the Coach batteries. This is true of the majority of motorhome makers. There are a few exceptions, but those are very rare. Since you got the Low Voltage error indicator, that means you need to check the status and reliability of the Coach batteries. Are they low on water? Are the connections loose or corroded? Doug