Explaining converters, inverters and generators – Part 1


By Wolfe Rose
There is a lot of confusion for new RVers as to whether they need a converter, inverter or generator. What’s the purpose of each, and if one is needed, what type or size? How do inverters vary from the converters built into RVs, or are they the same thing? To answer all of that, we first have to understand that trailers have two complete power systems, and why.

Starting at your shore cord, you take in 120V Alternating Current (AC), similar to your 15A wall power at home. This is the 30A or 50A designation you may hear referenced. You can pull much more power through that cord than the outlets you’re used to at home, but it’s the same “type” of power – 120V provided as a sine wave. This type of power runs your RV’s outlets, air conditioner and microwave. These are normally allowed to go dead whenever you’re unplugged from shore power. When your water heater or refrigerator are in AC mode, those too may be powered by this – but remember each of those can also usually run just fine off propane as well.

The second power system your trailer contains are your batteries, which provide 12V DC – the same type of power as in your car, which has polarity (+ and – terminals). This power runs your lights, fans, furnace blower and the control electronics for your refrigerator and hot water even when they are primarily powered from propane. These are all run from your batteries because “camping” trailers were originally assumed to need to be independent from shore power, even if that capability is only used by some RVers while in transit these days. Those who still camp away from power use this power independence to “dry camp” at sites without electricity, or “boondock” without a designated campsite. The problem is that your battery quickly runs down since it’s not being replenished – especially with high-drain loads like your furnace blower. This is why boondockers often install solar or wind power to recharge their batteries.

Recharging the battery (and preventing it from running down in the first place) is the job of the converter, which can be thought of as a beefy AC-to-DC battery charger. Some folks replace or augment their converters with “smart” multi-stage automotive chargers. A 40A converter designation means the converter can compensate for up to 40A of DC draw, running your lights and furnace without pulling power from the battery. Think of this function as a “wall adapter” for your battery-powered trailer. In addition to carrying the load for your batteries, the converter also recharges your battery from prior drains. The converter is an important bridge between the AC and DC power systems, in order to maintain the DC battery charge.

That said, our boondocker in the woods still can’t use his microwave or air conditioning, because they exclusively gulp down AC, not the relatively meager DC that’s available. In the next installment, I’ll discuss how to create AC power without a shore connection.

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Charles Young


Thanks for the work and articles going into this series. When you get to generators, I hope you go into how they can impact a surge protector. I have a pair of Yamaha 2000 watt generators joined with the cable designed to join them for 30 amp service., and they trip the surge protector. I made a ground-neutral/Edison plug for the 20 amp plug on the generator,but still is tripping the surge protector. I am getting very little help from neither the generator manufacturer nor the surge protector manufacturer. Any help you can give would be appreciated. Surge protector works fine with shore power.

Thanks – Charles


I am seeing several comments about solar and these are great. But I would like to see the staff expand on some of the info provided, in particular the discussion about the refrigerators. An RV 12 Volt DC (battery powered) / LP frig as compared to the residential frig in many 5th wheels which is only 120VAC. And how this affects your battery / inverter system – if you have one.

I understand these systems, but it is obvious from many blogs that this is not clear to many people.

Just a suggestion

Ron B

We are new to RVing. We purchased a 2002 27-foot Fleetwood RV recently and decided to purchase a Dometic 40 us portable ref/freezer to enhance our regular ref/freezer. It will run on 120 AC or 12 volts.

We are planning to place it in our rear storage area.

We don’t have a wall plug in the compartment, but do have two lights powered by 12 volt DC. I turned on my battery power and checked a receptical in our sleeping area just above the compartment that works off generator or shore power and realized my receptacles in my RV will not work on 12v. I have a converter. Do I need to switch over to a inverter?

J Hamme

I prefer shade when I camp so for that very practical reason I carry portable solar panels. I have a generator and use the 200 watts to keep batteries charged. It saves me money on generator fuel and maintenance. I have Renogy kit.

Tommy Molnar

I think the roof is the best place to install solar. If you sit them on the ground they’re susceptible to theft. If installed properly on the roof you’ll have no issues with your roof. I’ve had solar on my roof for 16 years (on my old trailer) with no issues. I’ve had the panels on my 2012 trailer since a month after I bought it – again with no issues. Since the only warranty issue in question IS the roof, if the solar is done right, it won’t matter because you won’t have an issue.

Dr4Film ----- Richard

I have one solar panel on my one piece fiberglass roof. The wires do not go through the roof. They are fed down through the fridge vent opening. This method should not void any roof warranty whatsoever.

Bob Novak

Can you or one of the other readers elaborate on adding solar? Two of the vendors at the Hershey show said putting solar on the roof was a no no. It voids the warranty because of the TPO roof seal. We visited a local Grand Design dealer last weekend and the sales person said roof mounted solar would void the warranty. Is there a 5th wheel manufacturer that offers roof mounted photovoltaic panels as an option? I installed a 30W panel, wiring and charge controller on my 1998 Chinook with no issues. I use it mainly to maintain the batteries while it is in storage. The Chinook has a fiberglass roof. Only staying in campgrounds that provide electric hookups really limits the options. Do I need to “void the warranty” to install solar on the roof? Comments?