Sunseeker House Batteries not charging

13.6 volts with converter charging battery is normal maintenance level for older chargers. With converter not charging, voltage at battery terminals should settle down to 13.2 volts over a few hours and with interior lights, etc., on it may drop to 12.6 or so. Old chargers will often overcharge batteries if rig is left plugged into shore power for long periods. Electrolyte levels will need to checked and replenished with distilled water often to keep electrolyte level above the plates. A rubber bulb type filler from an auto supply store allows accurate filling of cells without overfilling. RV converter/ chargers were designed for the rig being plugged into RV park power for a day or two and then the rig is driven for a number of hours and battery is charged by the engine's alternator, then you plug into shore power again at the next RV park. When you get home, you shut off the auxiliary battery switch to disconnect alarms and other things that continue to draw battery current and discharge the house battery. That's the theory anyway!