Without a properly working power converter, RV appliances and electrical fixtures won’t run. The converter ensures that power is properly distributed throughout the RV, 12V is supplied to the DC systems when the RV is plugged in to shore power or running off a generator, and the house batteries are kept charged. It is one of those “out of sight, out of mind” devices. However, an alternative to a converter is an inverter. This article will compare the functions of the converter and inverter. While there are many different types and sizes of the inverter, we will focus on the larger, permanently installed types that also incorporate a battery charger.
Whether converters are stand-alone or modular, they all perform the same three primary functions. First, the device converts some of the incoming 120V AC to 12V DC power for the house system when the RV is connected to shore power or generator. This prevents the house batteries from being drained when the RV has 120V power, and is the function for which the converter is named. An inverter does the opposite and connects directly to the RV batteries to invert (and rectify) the 12V DC to create 120V AC output. Unlike a converter, an inverter creates AC power without the need for shore power or a generator.
Converters also provide a means to distribute power to the different AC and DC circuits in the RV. This power distribution system takes the main power coming from the shore line or generator and distributes it to different branch circuits through individual breaker switches. There is a separate fuse panel for the various 12V house systems. Inverters do not have a distribution system built-in, so require separate fuse panels and breaker boxes to be installed. If you find that you are missing some AC or DC power in your RV, inspecting the circuit breakers and fuses first is suggested.
Finally, both converters and inverter/chargers keep the house batteries charged whenever the RV is plugged in to shore power or the generator is running. It should be noted that while converters incorporate a battery charging feature, the charging current available is often quite low. This means that these converters are not able to properly charge house batteries that are at a low state of charge. Stand-alone high-output battery chargers are required for this purpose. Inverter/chargers usually have much higher battery charging capability, often up to 100 Amps, and charge the batteries by simply reversing the inversion process when the RV is plugged in.
The most important thing to be aware of with an inverter is capacity. Because the inverter must produce ten times the voltage when inverting from 12V to 120V, it also pulls ten times more current from the batteries. For example, if you are watching a TV that requires a 5 Amp AC draw, the inverter is drawing 50 Amps from the batteries.
Although having an inverter installed in your RV is highly recommended, there are a few things to consider. First, due to the large current load required, inverters are unable to power large appliances such as air-conditioners, as the batteries would drain quickly. Generators or shore power are still required for this. Second, invest in a pure sine wave inverter, as regular inverters produce a square wave that can easily damage sensitive electronics. Finally, it is a good idea to incorporate a solar panel array with the inverter system. This provides for some battery voltage recovery while dry camping.
About the Author:
Coach-Net is pleased to welcome Steve Froese to our team of writers. Steve, an avid RV owner, traveler, and Coach-Net member since 2013, is the principal of “A Word to the Wise Technical Communications”, a published RV author, certified RV technician, and licensed Professional Engineer. He frequently collaborates with the “RV Doctor”, Gary Bunzer, and has worked with the RVIA/RVDA as a technical and training writer and consultant. Professionally, he works as a quality engineer and musician. Watch for more of Steve’s work in upcoming Coach-Net publications.
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