Topic: AV Electricity for RVers
Presenter: Steve Savage (motorhomereviewonline.org)
Presenter is certified RV technician, and publishes the above website.
All troubleshooting is done with the power off. However basic tools and parts are necessary to make repairs. Parts are found more inexpensively via the internet, rather than going to Camping World.
Appliance troubleshooting is done with the appliance in the RV. It should not be taken out until all other tests (proper continuity, ground, etc.) have been checked. 80% of the problems are due to loose connections. If you take an appliance in for repair and the service tech's proposed first step is to remove the appliance for bench testing (without doing the intial tests just mentioned), run -- don't walk -- to another service shop.
Voltage is how hard the electrons are being pushed. It's a measurement of pressure. When voltage drops, there's not enough pressure to supply the amperage.
Amperage is the quantity, or amount, of elecrons that are being pushed.
RVs are typically are 30 or 50 amps.
Switch (breaker) should be off before you plug in. First check the polarity to make sure the plug is wired correctly. Hot is hot, neutral is neutral, and ground is ground. Plug the polarity checker into the campground outlet, and it will confirm proper polarity. Then okay to plug in shorepower and turn breaker switch on. Reason for checking polarity is that metal surfaces in your RV may get "hot" of the polarity is not correct at the pedestal.
When buying a rig, get the biggest service possible. 50 amps is best, as it will let you use two air conditioners, etc. Two A/Cs are essential to cool a large motorhome.
Circuit breakers protect wiring and reduce the chance of fires. It does not protect humans -- just wires. Breakers are sized to the load (amps). If too many amps try to pass through circuit breaker, it heats up and opens (shutting off the current).
GFI -- ground fault circuit interrupters protect people. These are the plugs that have tester and reset buttons. You find them wherever they are within three feet of water source (e.g. sink) and any outdoor outlet.
How large of a generator or inverter do I need? This depends on the total number of watts of power that will be necessary.
100 watt light bulb needs 100 wats
13,500 BTU AC requires 1700 watts.
Power equation: watts = amps x volts
Operating range is approx 103-126 volts. Outside of that range you'll have a problem with your appliances.
Generators in RVs typically supply between 2,800 and 10,000 watts. All types work the same. An opinion: If you buy a diesel motorhome, buy a diesel generator. If you save few bucks on initial price, you'll lose it on resale. There is almost nothing to adjust on newer model generators. Typically they are operated through circuit boards. Often the will have a data port to report on history.
Generators need to work at least 2 hours per month under load. It needs to be continuous use. It's not okay to have 4 half hour sessions per month. If you purchase a used generator, don't look for one with very low hours, as it will likely not be in as good shape as one which has actually been used.
Generators won't run if there's less than 1/4 tank of fuel; if oil is low; if plugs are dirty; or if fuel is old.
Tip: After running under full load, generator should be allowed to run on low or no load for several minutes before shutting down.
Winterizing generator: Fill fuel tank and add fuel preservative. Run for 10 minutes under 1/2 load. Disconnect load, then stop generator. Spray fogger into carburetor. Change engine oil. Disconnect and store battery. Shut off fuel supply and plug tailpipe.
Inverters. In reality, if you're going campground to campground where there are hookups, there may be no reason to have an inverter. Needed to boondock, go to rallies where there are no hookups, etc. It doesn't take the place of a generator -- it's a purely optional device. It changes 12V DC from your batteries to 120V AC current from your AC outlets.
Xantrex will not manufacture modified sine wave inverters after next year. The "new" inverters will all be pure sine wave inverters. They are more expensive. Modified sine wave current can destroy laser printers, and will be problematic for microwaves, flourescent lights, and other small loads such as recharging devices. The latter may become hot.
Inverters work best with resistive loads such as lights. They are not good for heavy loads such as refrigertors and air conditioners.
Some inverters have three stage ("smart") chargers. If you don't have one, you cannot fully charge your batteries. The old style standard chargers will result in shorter battery life.
AC Electric Accessories for RVs:
Surge Protectors: These protect against high or low voltage. If you have a high end inverter, very likely it's built into that unit. If voltage is too high or low, it will shut off the electrcity. Need to be wired to the output side of the transfer switch, so that it will protect both from errant shore power and from errant generator power.
Autoformers -- can make up for a 10% drop in voltage.