Inverter Sizing

What Size Inverter Do I Need for My RV?

Are you an avid camper or perhaps a busy folk planning to go off the grid with family and friends during the weekend? Whatever the case is, one of the greatest dilemmas most people face is whether to carry their home comforts in an RV. Appliances such as your laptop, TV set, microwave, hairdryer, phone/tablet, and a coffee maker are essential when RVing. However, most of them rely on the 120V AC to function. Since your RV’s standard battery cannot supply enough current to power them, one question that will definitely cross your mind is “what size inverter do I need for my RV”.

Now, when we speak of size, we don’t necessarily mean the physical dimensions. Instead, what we mean is the capacity of the inverter in terms of the amount of wattage it can output. In this short guide, we will break down this context in plain words to help you understand how much is just enough.

 

What Size Inverter Do I Need for My RV: Step-by-Step Guide

First, What’s an Inverter?

Although there are a few RV models that have factory-installed inverters, most of them are equipped with converters instead. Now, these two terms look basically the same and can be confusing at times. An RV converter on its side is designed to convert 120V AC (from your generator or shore power) into 12V DC to either charge your RV’s battery or power some of your RV’s low voltage components such as LED lights and car cigarette lighter.

When it comes to the inverter, this electronic module does the opposite. Unlike the converter, this one converts the 12V DC current from your RV’s battery to 120V AC current to resemble the standard household electricity.

 

How Does it Work?

Just as we mentioned earlier, an inverter is tasked to invert your battery’s 12V DC into 120V AC current to power most of your household appliances present in your RV. So, if you choose a large enough inverter, then it simply means that it will supply enough current to power all your appliances.

Now, one rule of thumb that applies to electricity is that the moment you invert your battery power, you increase it 10× from 12V DC to 120V AC. This causes a 10× increase in the input amps as well, meaning that your a/c appliances, such as your hairdryer, will draw more amperage from your RV’s battery.

For instance, let’s assume you have a 1500 watts appliance that draws 12.5 amps at 120V. Once you invert the power from d/c to a/c, such an appliance will draw 125 amps from the battery (a 10× increase).

Now, since you’ll be drawing a lot of current from your RV’s battery (enough to deplete it), you will need a converter charger to convert the household 120V (AC power) into 12V DC to recharge your battery. The recharging can be done via shore power or simply generator power in case you’re off the grid (in a campsite).

 

What is Modified Sine and True Sine Wave Inverters?

Something else you need to know about inverters before you can decide which size will work perfectly well for you is the modified and sine wave inverter flavors. Now, if you’re new to RV inverters, some of these terms are likely to leave you scratching your head in bewilderment. However, you don’t have to worry as we will explain everything in plain words.

Now, a modified sine wave (MSW) inverter is an older technology that was developed years back as a cost-saving solution following extremely high prices of the true sine wave inverters. Although they are efficient enough to power many standard appliances (such as motors, non-digital appliances, lights, lamps, pumps, and various power tools), their waveform can cause intermittent issues when it comes to powering modern appliances such as those with motors and digital timers.

Since you’re likely to carry your laptop, LED TV set, a coffee maker and a digital microwave, a modified sine wave inverter might not power these appliances at all. For this reason alone, a true sine wave inverter will definitely be the only logical option.

Unlike the traditional MSW inverters, the true sine wave (TSW) inverters are designed to generate a cleaner output analogous that’s indistinguishable from the normal household current. The current is clean and sufficiently large to power all of your home appliances including those that draw a lot of power.

However, just as we mentioned earlier, the only trade-off with these two types of inverters is the price as TSW inverters can get really expensive.

 

What Size Inverter is Enough?

Now that we’ve mentioned everything you need to know about inverters, we believe it will now be easier for you to figure out the math of how much is enough for you. In this last section, we will briefly discuss three factors you’ll need to keep in mind when choosing the best inverter for your RV. These are:

  • The type of appliances you have
  • The available RV battery
  • How long you’ll run the appliances

  • 1# Type of Appliances

The first thing you need to figure out when choosing the right RV inverter is the total wattage your appliances will need for them to operate. Just to be on the safe side, always make sure that you pick an inverter with higher wattage (about 15-20%) than the total wattage of your appliances.

Now, let’s assume the total wattage of all your appliances is 2050 watts. To determine the size of your inverter, you’ll need to add the extra overhead (in this case 15% to 20%) to the total wattage of your appliances. So, you’ll have;

20/100 × 2050 = 410 watts   [We chose to go with an extra overhead of 20%]

410 + 2050 = 2460 watts

So, your RV will require an inverter with a power rating of 2460 watts. Since you can’t find an inverter with this exact power rating, you will need to get a model with the closest higher power than this which in this case, will be 3000 watts.

Although you didn’t ask, the reason why we added the extra overhead is to mitigate the peak demand of some of your appliances. Now, if you happen to switch on any appliance that has a motor or a compressor (such as a microwave or a fridge), it will start at a higher peak rating for several seconds, then lower significantly.

This brief burst of power is what is called the peak rating and it can easily shut down or damage your inverter if it’s unable to meet this high power demand.

 

  • 2# Check Your RV Battery

Once you’ve selected the right inverter for your specific appliances, the next checkbox you’ll need to tick is whether your RV battery bank is large enough to power your inverter. As a rule of thumb, every 100Ah of deep cycle battery is enough to power 1000 watts DC to AC inverter. So, if you have a 200Ah or a 320Ah deep cycle battery or lithium battery, then it should manage to power a 2000 watts or a 3000 watts inverter respectively.

 

3# How Long Will You Run the Appliances?

To determine how long you can run your RV appliances, you need to first figure out the type of battery you’re using. Here, you should pick a battery from a reputable manufacturer with details of how long it can output maximum Amps.

Some reputable brands such as Revolution Power 100Ah can deliver consistent power to run a 1000 watts inverter for about an hour. Let’s say you have an appliance (it could be a laptop, a light bulb, a TV set, a ceiling fan, or a Smartphone) that draws 50 watts continuously. So, this will equate to about 4 Amps at 12V. If you’re using 1000 watts inverter, then it simply means that you can use any of these appliances for up to 24 hours.

 

Conclusion

So, there you have it. As you can see, camping or RVing doesn’t mean that you should give up the comfort you enjoy at home. By reading this short guide, you can easily understand what size inverter is enough to power all your home appliances while still going down the road.

As you can see, having a reliable inverter doesn’t just mean the price. You need to calculate the size of the inverter and the quality of the battery to ensure they’re safe and reliable enough to power all your appliances without shutting down or causing any damage.

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