How Does an Inverter Work in an RV? [DC to AC]
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A power inverter is a system of converting DC power that is coming from your battery or solar panels into AC power. Having an inverter in your RV or camper is very useful if you ever want to get away from the shore power but feel guilty for making loud noise with a generator if you have fellow campers around.
If you ever find yourself out in a wild without shore power, the only way you can power your AC appliances (quietly) is by using a set of batteries and an inverter! RVs usually do have an inverter installed (either by the factory or previous owner), but in some cases, you would need to go out and get it.
All the comforts that we want in our home or work, generally come down to using electronic and electrical equipment and they should be available any place we go. This is where an inverter comes in! Inverter in the motorhome or RV has one primary function:
Converting DC (Direct Current) into AC (Alternating Current)
If you are plugged into the shore AC power, then you have all the power you need. Once you get away from the grid and still would like to use your AC appliances, the only way to supply them with power is by using an inverter!
AC (Alternating Current) powers many things in your RV or camper like a refrigerator, microwave, hair drier, TV, etc. and regardless of whether you use solar power or battery bank (which supply you with DC power), you will need an inverter to give them the right type of current.
People use the inverter in a camper or RV generally for the following reasons:
- To use power from solar panels
- To use power from the batteries
- As an alternative to using a generator
The following video will give more details on what to expect from an inverter:
Having a transfer switch with your inverter is extremely useful as well, since you will be able to power ALL your outlets when needed and shut them down when not in use. Check out this video on the RV inverter transfer switch installation (diagrams included):
Why do you need an inverter in your RV? This is your home away from home and you probably want to use some electrical or electronic devices when you are out there in a wild. You don’t want to ruin your beautiful scenery with a loud generator, do you?
Unlike car inverters, RV inverters are larger and some of them serve a specific purpose (like powering both legs of your 50-amp service, for example, meaning 120vac/240vac split-phase capability). But in general, a good, preferably pure sine wave inverter of about 3000-watts, should suit most RVers.
If you still need a small inverter for your dash, a car inverter should do the trick. Here are some things to consider before buying an inverter for your RV or motorhome:
- Technology. Pure sine wave inverters may cost more, but they will give better quality power to your devices. Modified sine wave inverters are cheaper, but you get what you pay for…
- Wattage needs. Adding up the wattage needs of all the devices that you would like to be running off the inverter will give you a good estimate of the inverter size that you may need. Don’t forget to add 20% on top of that to be on the safe side and keep inverter efficiency (varies by manufacturer) within your calculations.
- Being practical. How many devices do you really need to run at the same time? You can simply add the wattage of the biggest devices that could possibly be used at the same time and the rest will be used as one of them gets unplugged.
- Space considerations. How much space do you have to accommodate such a large setup? It may be worth it for you to get a device that combines inverter and converter and that can really help you optimize how your power is being used.
- Cost considerations. You can find an RV inverter for sale relatively cheap, but will it do the job that you want it to? Again, before buying anything calculate your wattage needs properly and consider what kind of equipment you will be powering.
- Battery considerations. Having a good battery bank = happy camper in the event that you don’t have AC power nearby or a generator available! If you have a little bit of money to invest in the comfort of your trips, you may want to go for lithium deep cycle batteries! You can discharge them deeper, they last longer and require minimum maintenance (in comparison to lead-acid).
To size your inverter properly, you will need to combine the wattage of the biggest devices that you would like to use at the same time and give yourself a 20% headroom (for unexpected situations).
Inverters do have the ability to handle initial startup surges (peak power), but it’s only for a short period of time. They generally double their capacity (varies by manufacturer):
The number we need for sizing an inverter is:
and NOT “Peak Power”. “Peak Power” comes and goes, “Continuous Power” stays with your equipment. Do NOT use Peak power or Surge power ratings for sizing your inverter.
There is also something called: “Output power”. If your microwave is labeled at 900w, this doesn’t mean that it only uses 900 watts! It means that the “output” is 900w (how much power it needs to run is labeled by “input”).
Here is an example:
You need to look for “input” on the label to size your inverter correctly! Also, while planning your life on the road,
try to get the appliances that are very energy efficient
When the wattage amount is taken care of, now you will need to decide on the sine or modified sine wave technology. If you compare a picture of a modified and pure sine wave, you will see why it’s easier for your equipment to run on the sine wave vs the modified sine wave.
In general, using the Pure sine wave inverter should not affect the lifecycle of your equipment. Modified sine wave technology, on the other hand, is known to be more “stressful” and damaging for your equipment and appliances.
Inverters that produce “square wave” are NOT recommended at all due to reliability and safety issues.
Also, there is another very important thing to keep in mind and it is:
the EFFICIENCY of your inverter.
It varies from manufacturer to manufacturer with the best ones having 90 to 95 percent efficiency. When sizing an inverter, please remember that output power will NOT be one-to-one (unless it is stated specifically on your model of the inverter).
There is more information on sizing your inverter in this article: “How Fast will Power Inverter Drain Battery?”. Here is a nice infographic pin on inverters for your reference. Feel free to save it .
RV Inverter Charger
An inverter charger is a device that combines an inverter, converter, and transfer switch. If you like dry camping or boondocking, you need this device!
Typically, many RVs come with a built-in converter (and sometimes inverter), but they are usually not very good quality. It is a very common practice for new owner to replace their old inverter and converter as soon as they get a camper!
The purpose of the inverter charger in your RV is to supply you with the right type of power and at the right time. This single unit will replace 3 vital components of your RV electrical system, which are:
- Transfer switch.
Split Phase Inverter Charger
Do your appliances require a split-phase service or you need to power your 50-amp RV? Following inverter-chargers are specifically adapted to produce a 120/240-volt split phase.
Some inverters can only produce this type of electricity if you wire two of them together (and set up as “split phase”), others could produce 120/240 volts out of European Version 230-volt (50hz) by adding an autotransformer (and changing settings to 240v/60hz).
The best solution to powering 50-amp RV service is the inverter that is already wired for a 120/240-volt split phase service. This also means that it will have a pass-through capability of 12,000 watts (6,000 watts on each leg):
50 amps x 120 volts = 6000 watts
Inverters like that require less wiring, which means – fewer possible complications.
50-amp Power Inverter
You can wire your 50-amp RV’s inverter in several ways and here is a more detailed explanation.
Stackable Split Phase Inverter
When you stack your inverter or inverter-charger, possibilities are endless! You can stack as little as 2 inverters or as many as 10 inverters to get a power boost and other benefits that your specific setup can offer you (ex. split-phase, 3-phase).
If you need to stack your inverters in split-phase mode, you need to make sure, first of all, that they come with this type of option. Second of all, get a professional to do it! This type of wiring and configuration is very complicated and dangerous.
Here is more information from Victron. This is a popular solution for wiring 50-amp service in an RV, which means that you will finally get the most of it during dry camping times:
50 amps x 120 volts = 6000 watts
6000 watts x 2 (legs) = 12000 watts
Click on the white button above to find your electrician!