1980 Shasta Motorhome Electrical System
storage battery -vs- electrical generator
The Shasta Mini Motorhome gets electrical power in one of three ways. When the motorhome is parked and the engine is turned off, power can be supplied by either the Shoreline connection (see diagram), a 12 volt power storage battery (which is recharged as the motor is running), or a gasoline powered electrical generator (see diagram) stored in a locked, outside compartment. What the motorhome is doing at any given time determines which of these systems is used as the primary power supply.
The gasoline generator is an optional feature on this particular model of motorhome. It draws fuel directly from the motorhome's gas tank and can supply 120-volt electricity whether the motorhome is in motion or not. The generator can be turned on by a remote control starter located on the main monitoring panel (see diagram). It is, in my opinion, the best way to go in terms of reserve power if you need a constant, uninterrupted supply. it'll run as long as there's gas in the motorhome itself and is more reliable than the 12-volt storage battery (which has a limited life between chargings, at best).
The motorhome I bought doesn't have the factory gas generator and relies instead on a 12-volt storage battery for reserve power. 12-volt power is supplied to the motorhome in three ways, by the motorhome's own 12-volt battery, the reserve, 12-volt storage battery, or the 120-volt power converter, which, as the name implies, converts 120-volt AC electricity into 12-volt DC power. The storage battery supplies power to the refrigerator, furnace blower, monitoring panel, water pump (see diagram), power vents, range hood fan and light, interior lights and 12-volt receptacles (see diagram). Recharging this battery is done in one of two ways, either by the motorhome's alternator (when the engine is running), or the 120-volt power converter (when the engine is idle and using an outside source for 120-volt current). An isolator allows interaction between the engine's battery and the reserve battery, yet prevents the motorhome's 12-volt system from drawing power directly from the engine's battery when the motor is off, which, and it is in all sincerity when I say this, is a real good thing to have. The isolator, I mean.
When supplied by a 120-volt power source, the 120 volt power converter (see diagram) supplies power to each of the motorhome's 12-volt systems. Fuses in the converter protect each 12-volt circuit and are accessed by opening the converter cover. You can find a listing of all the circuits on the inside of this cover. The refrigerator and water pump are on separate fuses and some fuses protect circuits with more than one function.