Once you’ve gained possession of your dream motorhome, you’ll feel as if nothing can stop you now.
That unbridled sense of freedom, the low cost of living — full-timing in a motorhome is an entirely different way of life. You can escape the rat race and live how you’ve always wanted.
Motorhome life has long attracted adventurers, dreamers, and those who do things differently. Still, let’s not get carried away with the fantasy without highlighting some real-world challenges and factors you must consider carefully.
One of the most significant considerations — especially when you’re going off-grid — is power, which will more often than not lead you back to one simple question:
What size inverter do I need for my motorhome?
How to Choose the Right Size Inverter for Your motorhome
Now, if you’re new to motorhome life, you might be wondering: What is an inverter, and why do I need one?
Inverters are typically used for off-grid living but are usually required anytime you wish to use AC-powered devices in your motorhome. Most motorhomes come with DC batteries onboard that are already connected to your lights and built-in appliances. But they typically can’t handle household appliances such as a microwave or a camper fridge that’s not built-in.
Essentially, an inverter is a device that transforms the DC power stored in your battery banks into the AC power that most everyday electronic devices and appliances use.
If you’re using solar panels to power your motorhome, the energy gathered by the solar panels will need to pass through an inverter before you can use it. If you’re using a portable power station or solar generator from a manufacturer like EcoFlow, the inverter for your solar power is already built-in.
However, if you’re building your own solar power system component-by-component, you’ll need to select a standalone inverter.
Now we know what an inverter is, which size is best? The answer greatly depends on your motorhome’s size and how many power-hungry appliances you have onboard. You’ll also need to consider how many electronic devices you will run concurrently.
motorhome and Camper Inverter Size Calculator
To calculate the size of the inverter required, you’ll need to add up the individual wattage of the appliances you have in your motorhome or campervan. Also, remember that larger appliances, such as microwaves and fridges, come with a standard wattage and a surge wattage. Standard wattage is what the machine needs to run continuously, while the surge wattage indicates the energy necessary to turn the device on in the first place. The surge power required is often double the running wattage — without it, the appliance won’t start up.
But before you run off looking for a massive 24 kWh inverter, things don’t quite work like that — thankfully. An inverter doesn’t generate or store power; it only converts it. You need to calculate how many appliances you’ll run simultaneously to determine the size of the inverter you need. For most motorhome full-timers, that figure generally comes out around 2000/3000 watts unless you’ve got a larger-than-average number of devices working simultaneously.
Once you’ve calculated your wattage, the general rule is to add an extra 20% to ensure you have additional capacity above that cut-off point.
Let’s say you need 2000 running and 3600 surge watts to turn on and operate your desired appliances. Calculate an extra 20% above the surge watts:
3600 watts x 1.20 = 4230 watts
To turn on and run appliances of this wattage, you’ll need a 5000-watt inverter at least.
If you’re struggling to calculate what size inverter you need, you can always use a ready-made inverter calculator to help you crunch the numbers.
Can an Inverter Power a Whole motorhome?
As long as you’re generating sufficient power from a solar or fossil fuel generator, the right size inverter can run whatever appliances you like as long as it possesses adequate wattage. If you’re boondocking without shore power for long periods, make sure you have enough solar panels or fuel to generate the power you need.
How Many Batteries Do You Need?
Batteries are another critical component of powering your motorhome. It’s crucial to ensure that your batteries are compatible with your inverter. When an inverter is considerably larger than the batteries, it will drain them in no time.
You should avoid completely running batteries down as it diminishes their efficiency over time. As a loose rule, keep your batteries above 40% charge whenever possible to maintain their overall health.
To get an idea of how much battery storage you’ll need, you can start with a rough wattage output, say 2,000. You’ll also need to figure out the running amps:
Amps = watts/volts
If you’re using a typical 12V motorhome battery, use the following calculation:
2000 watts / 12 volts = 166 amps
Suppose you only want to run your appliances for 2 hours daily. You’d calculate 166 amps X 2 hours = 332 amps.
There’s always some energy loss in converting DC to AC, so you’d likely need to round up to 400 amps in this example. A 400 amp battery would run at 2000 watts energy consumption for approximately 1.2 hours.
Many high-quality inverters will automatically switch off when the batteries run low or if they’re not in use for an extended time. Lower-quality inverters may continue to draw energy from the batteries even if no appliances are turned on. Always ensure your inverter is turned off if you’ll be away from the motorhome for extended periods.
Features of motorhome Inverters
Inverters come with various features. In its most basic form, an inverter simply converts DC power to AC power. But as you begin to go up in price point, plenty of beneficial features are worth considering.
As mentioned, some inverters have an automatic shutdown that protects against an overloaded or dormant system. Others have a remote control or mobile app to make adjustments or switch the inverter on and off as needed. Larger and more expensive inverters usually have more output options — such as USB ports — and cooling fans.
Portable power stations, like the DELTA Pro from EcoFlow, have built-in two-way inverters and the capacity to hook up to solar panels. You can charge any EcoFlow portable power station using multiple methods, from shore power to solar panels.
What to Look for When Buying an Inverter for motorhomes
motorhome inverters come in two models: pure sine power and modified sine wave power. Let’s start with the first, which is both superior and more expensive.
Pure sine power is like the energy in our homes. Pure sine inverters produce a smooth, clean power supply that can run most household appliances.
Modified sine wave power inverters, on the other hand, are cheaper but might struggle with larger appliances as their polarity constantly switches back and forth from positive to negative. Modified sine wave inverters are suitable for smaller campervans with low overall wattage. But will probably be unable to cope with more substantial electronics such as widescreen TVs, microwaves, and heating or cooling devices.
Pure sine power is always preferable but not always needed and certainly more expensive. Besides that, think carefully about the inverter size you need. An inverter that’s too small will struggle to provide the electricity you need. If your inverter is too big for your batteries, it will drain your energy storage without providing optimal conversion.
You should also be aware that modified sine wave power inverters often produce a humming sound that can be disruptive. Pure sine power inverters are typically much quieter.
Our last point concerning buying an inverter is that you don’t need to purchase all the power components for your motorhome independently. Modular power kits come with a battery, an inverter, and everything else you need to power your motorhome lifestyle fully.
Simply calculate what size power kit you need to meet your off-grid energy requirements and plug-and-play.
Difference Between motorhome Inverter and Converter
Inverters and converters both do the same thing but in different directions. A motorhome inverter transforms DC power into AC energy, while a converter does the opposite by converting AC power into DC to charge a motorhome’s onboard batteries.
Before you worry about adding an extra piece of equipment to your motorhome, know that most motorhomes come with a standard converter that is usually more than adequate for your needs.
Living the motorhome dream is always enticing, but it comes with caveats and factors you must carefully consider before throwing everything you need in the back and disappearing over the horizon.
Inverters, batteries, and generators are hardly the most exciting aspects of motorhome living but are vital if you’re looking to go boondocking or off-grid for any length of time.
Your motorhome power supply is one area where it certainly pays to research, calculate how much electricity you need, and find the ideal equipment to support your off-grid motorhome lifestyle.
Shop EcoFlow for all the options you need to run just about any appliance on your motorhome and gain your energy independence. Once you’ve got the motorhome power system you need, you’ll be all set to hit the road fully charged for whatever adventures await.