Recommend all RV owners buy a cheap multi-meter, read the directions, and learn how to use it to check 12 volt DC voltages as well as electrical continuity, (to see if a fuse is burnt) Be verrry careful checking any 120 volt AC voltages,danger of electrocution!! If you can, get an electrical schematic for your rig from the maker and spend some time understanding the schematic symbols and connections. Take a look at how your RV generator is grounded and connected to the 120 volt system. Learn how the emergeny start system works. Understand how the shore cable plugs into the generator (or) how the automatic transfer switch provides 120 volt AC shore or generator power into the RV. Learn how the roof AC unit needs to "rest" for 10 minutes when shutting it down and turning it back on as when switching from generator to shore power.
Next find your converter/charger and note the heavy guage wires are securely connected to it with allen type set screws, these go toward your house battery(s) through a solenoid relay and which is connected to your house battery disconnect switch. There may be some automotive type fuses and circuit breakers in the circuits, on a power distribution panel and also some more fuses located near the battery(s. Look at your house batteries and the cables and connectors clamped to the terminals. There may also be some smaller guage wires attached to the battery connectors with ring terminals make note of their colors and what terminals etc., they are connected to for future reference. The connectors will need to be removed from battery terminals and cleaned with a wire brush. Electrolyte levels need to be checked once every two months and distilled water may need to be added to keep electrolyte levels above the plates. Find your fresh water pump and it's wiring including a small Intellitec device that connects to remote water pump switches. There are a lot more 12 volt wires and connections to things like the furnace, and electronic controls on appliances that must make good contact for them to work and work properly. Having a good general understanding of 12 and 120 volt electrical systems, and where components are located, will/may help you when electrical problems arise out on the trail. Have a good selection of fuses and spare 12 volt light bulbs, maybe some electrical tape and some crimp type connectors and splices, a crimping tool, wire stripper, wire cutters and some wire will come in handy for repairs on the road.
Note: Fully charged house batteries read around 12.6 "resting" volts some hours after being charged by the converter charger While being charged from the converter charger , batteries should read around 13.6 volts. With engine running and being charged by the engine's alternator, batteries may read around 14 volts.
Having some understanding of how to troubleshoot and fix 12 volt electrical system problems or at least being able to describe problems to a technician will come in handy.