RV Inverter: How to Choose the Best Option

So, you want to start dry camping? or perhaps just feel more comfortable “off the grid”?  That doesn’t mean you have to give up your TV, microwave oven, hair dryer, or some of your other 120 VAC (traditional items you plug into a wall socket) equipment. You could of course buy a generator to power your gear, or even just to keep your batteries charged. However, there are often limitations on how long you can run one and the expense of doing so. You might consider installing a RV inverter to compliment your power system.

Virtually every RV comes equipped with a converter. Not to be confused with the “RV inverter”, the RV converter as the name implies, converts 120 VAC electricity into 12 VDC(think 12V cigarette lighter receptacle). It charges your batteries and powers your lights, water pump, and all the rest of your 12 volt equipment. The RV’s inverter does just the opposite. It converts 12 VDC from your battery into 120 VAC, standard household type electricity.

Before you buy your RV inverter, you need to decide what kind is most appropriate for you. Inverters come in two flavors and in a wide variety of sizes. The first  flavor utilizes a modified sine wave (MSW) output. The other has a true sine wave (TSW) output. Which one you need will depend on what equipment you will want to run off your RV inverter. The output of the TSW inverter is indistinguishable from normal household current and, if sufficiently large, will run anything you connect to it. The down side, is that they (especially the big ones) get rather pricy in comparison.

RV Inverter: Sine Wave Type Diagram

Not all Modified Sine Wave (MSW) inverters are created equal. A true sine wave is illustrated above (red line). Also shown are two different modified sine waves (blue and green). The modified (blue line) wave is much closer to the true sine wave (red line), and is less likely to cause problems with your electrical powered items. For anyone not formally trained in electrical engineering it may be simpler to know that a traditional power grid, like the one you enjoy when you plug in at a hotel or at your sticks and bricks house, would look like the red line. If you choose to purchase a MSW (blue or green line) RV inverter, the output you receive could cause intermittent issues with your sensitive electronics such as televisions and computers as described below. The trade off, as with anything, is cost. TSW inverters tend to be significantly more expensive than their MSW counterparts .

The MSW RV inverter will run most of your gear, but not everything. Anything with a power brick, such as a laptop computer, will work fine. All of your battery chargers will work, as will your hair dryer and small power tools. The TV will work, but depending on the particular TV and particular inverter, there be some lines running through the picture. I have operated two different microwaves with two different MSW inverters, but I have heard of problems with some combinations. With one exception, modern electric blankets with digital controls absolutely will be destroyed. If you can still find a blanket with the old analog control, it will work. The one exception is the Soft Heat blanket from Perfect Fit. It uses an 18 volt power brick and will work with a MSW. It is a little more expensive than most, but is a very nice blanket.

Inverters are available in almost any size, but unless you have a huge battery bank, anything over about 3000 watts will use too much battery power to be practical. To decide what size you need, check the wattage requirements of what you want to power, and get an inverter that is a little bit larger. Forget about running the air conditioner, but almost anything else is reasonable. Each RV inverter will have a continuous rating and a peak rating. Mostly, you want to look at the continuous rating, but microwaves, power tools, air compressors, and some other devices will require a higher peak rating.

The typical power power consumption of devices that you might want to be running are listed below. Simply add up the wattage of everything that you might want to be operating at the same time.

RV Inverter: Power Consumption Diagram

Device
Power (Watts)
12 vdc Current (Amps)
Microwave Oven
1200 -1500
100 - 125
Queen electric blanket
250
21
Coffee pot
1200
100
TV
180
15
DVD
60
5
Computer
100
8
Hair Dryer
1200 - 1600
100 - 133
Cell phone charger
20
2
Table 1

A more robust list of RV appliances and their power requirements.

You also want to determine if you have enough battery power available. There isn’t much point in installing a 3000 watt inverter if the 250 amps needed to supply it will run down your batteries in half an hour. To estimate your anticipated power consumption, take the current (from column 3), multiply by the number of hours per day that you expect to use it. Add up that figure for each device, and compare the total to the Amp-Hour rating of your battery bank.

You will also want to check the efficiency of the RV inverter that you are selecting. Because the process of converting from 12 VDC to 120 VAC generates heat, the inverter will always draw more watts from the batteries than it putts out. Some brands have greater losses than others. Read the specifications carefully.

Be aware that a RV inverter uses some battery power whenever it is turned on, even if nothing is connected to it. You want to be able turn it off whenever it is not being used. Some large inverters have an optional remote on/off switch. I bought my remote after the first time I had to go outside to turn it on in the middle of a cold night, while bare footed and in my underwear. If you will be installing your inverter in an outside battery compartment, or anyplace else that is not easy to reach, you will definitely want one with this feature.

The bells and whistles on the different models vary considerably. Some may have digital displays to indicate the battery voltage and power output. Others display the same information with bar graphs. Some keep cool with fans that run continuously. Others save a little power by switching the fan on and off with a thermostat.

Most Recommended Brands for the Best RV Inverter :

Magnum-energy-rv-inverter-best

MAGNUM – 3 Year warranty and made in the U.S.A.  They manufacturer both TSW and MSW inverters along with combo units with chargers. Well regarded by RV technicians.

Outback-power-rv-inverter-best

OUTBACK –  5 Year warranty. Also with a full line of RV inverter/charger products. Highly rated.

xantrex-rv-inverter-best

XANTREX – 2 Year warranty on most products. Full line of RV power products. Historically great products though recently the company was sold so some have went with other options.

Its not to say that there are not other brands that may work well for your application, just that the brands above are time tested by other RV’ers to be the absolute toughest, best performing, and offer the best warranty in their class. You should consider Amazon.com, Campingworld.com and Invertersrus.com to ensure you get what is right for you at the best price.

Conclusion

The scope of this article is to offer a better understanding of the different options and considerations when looking for a RV inverter. Once you have narrowed your search for your RV inverter you may want to keep an eye out for my follow up article which will review the process for installing your RV inverter. Be sure to read PART 2 of this RV Inverter series where I explore options for installing your RV inverter.

About the Author

Joel Orlinsky is a retired engineer from the medical device industry. He currently owns a fifth wheel and a 19 year old class B motorhome. He also has had an even older class C that needed lots of TLC. He picked up plumbing and electrical skills while working on previous traditional homes that he owned. Being naturally cheap frugal, he has consistently performed much of the maintenance on his RV’s.  He enjoys photography, birding, canoeing, and blacksmithing. Though none of them have anything to do with repairing RVs, he is hopeful that blacksmithing might come in handy some day. You can reach him via email at orlinsky@ameritech.net or by using the comments section below.