Type to search

Inverter blog Power Inverter

Inverter for motorhome


Inverter for motorhome ? You started building a motorhome. You bought a stationary battery to power your electrical equipment, but only then did you find that your BatteryBattery is 12 volts and that no home appliances work on it. Calm down today am going to explain how to solve this problem!

In past articles, we have talked about the main concepts of electricity, such as voltage, current and power; We also explain why you should buy a stationary battery for your Motorhome.

With so much technology that we do not live without, today the motorhome must be able to energetically meet the needs of its owner. In order to reduce the cost with such demand, the most common is to install solar panels on motorhomes already manufactured. In addition, some manufacturers, seeing this need, have launched factory solar motorhomes.

Many people who are starting to build a motorhome want to have specific amenities that a typical home has, such as a refrigerator, a hairdryer, a blender, among other appliances. But the point is that these devices are designed to work on your home’s power grid, which in most parts of Brazil is 127 or 220 volts. The problem is that batteries usually work with 12 volts of voltage. The result? None of your electrical appliances will operate connected to your BatteryBattery.

But don’t worry, because for this problem there is a solution: THE INVERTER (also known as a voltage inverter, or 60 Hz ac / dc converter). Jeez, what lousy word is that?

The Inverter is a device that converts DC (12volt) especially your battery voltage to 127 or 220 volts and also turns the direct current into alternating current, and thus operates your electrical appliances inside your Motorhome. But since not everything in life is free, using the Inverter comes at a cost. When converting, the Inverter loses up to 20% efficiency. That is, when using a device that consumes 10-ampere hours connected to an inverter, you can spend up to 12 amps of your BatteryBattery. And believe me, this extra consumption makes a big difference and affects the electric range of your Motorhome, i.e. the time you have power without having to stop to “replenish” your BatteryBattery.

Not all electrical appliances have a 12-volt version. That’s why some travellers assume they have a simpler life and forget about home appliances. But for many, this is not an option, because if you want to become a digital nomad, for example, you will probably use a notebook or photo camera, and virtually all of these devices are designed to be charged with 127 or 220 volts, which are the voltages used in the power grid. 

Therefore, you decide that you will need an inverter. 

Which Inverter to choose for my Motorhome?

Yes, there are 500 watts, 1000 watt, 3000-watt inverters. Which one to choose? It depends on the power of the electrical equipment on your Motorhome you will connect to the Inverter. The logic is to have an inverter with more energy than the electrical appliance. So, to use a 1000 watt hair dryer, for example, it would be enough to have a 1500 watt inverter, correct? Not really. Equipment that has a motor or compressor, such as a hair dryer or refrigerator, has a peak consumption in the first few seconds when it is turned on to compensate for inertia. Lighter? Well, the logic here is the same!). It means that by plugging in a 1000 watt power dryer, Its peak consumption could easily exceed 1500 watts from your Inverter. The result is that you may burn the Inverter, or the electrical appliance may burn or not work.

Some experts suggest that you should use a 10X inverter powered by a motor or compressor. For example, to use a 200 Watt refrigerator, you would need a 2000 Watt inverter. That’s why many people say you can’t use this type of equipment in the Inverter. Power may, but you will need a very rough inverter. And as you can already guess: the higher the power of an inverter, the more expensive it is. But to be clear, this account of a more powerful 10X inverter is only for electrical appliances with a motor or compressor. For charging notebooks and mobile phones, for example, an inverter just a little more potent than consumption solves. I, for example, use an 800W inverter and get the job done.

Can I use modified sine wave inverter for my Motorhome

Yes, you can, There are several types, but the most common is “Pure Sine Wave” and “Modified Sine Wave”. Remember the 60Hz back there? The time has come for you to learn what this means … In direct current, the energy flows straight in the same direction as if it were a river. In alternating current, which arrives at your home through the power grid, the voltage pulses several times per second, 60 times per second to be exact, so the 60Hz. However, not all inverters can deliver an accurate 60Hz current. They end up varying this frequency a little. These inverters are called a modified sine wave. Already pure sine wave inverters, are those that deliver a perfect, absolute frequency, without variations.

Nevertheless, the modified sine wave inverter works well with most electrical appliances. But the most modern devices, with timer and speed regulation, do not like much variations in frequency. They will even work, but they risk spoiling faster. One analogy I like a lot is with pure and mixed gasoline: your car will also run on contaminated gas. But in the long run, the chances of getting into trouble are higher.

To summarize the mass, the idea is that you carry the minimum of 127 and 220-volt electrical appliances on your trip. And for those you consider essential or indispensable, you should use them whenever possible in places like campgrounds that offer a powerpoint from the power grid. After all, even with a top of the line inverter, you still need to pay attention to how much these electrical appliances will consume energy. Well, there’s no point in investing in the top Inverter on the market if your Motorhome’s Battery runs out in a few hours.

Consuming less energy is a way to increase the electric range of your Motorhome. But there is another way to improve this autonomy, which is to have a source of electricity generation. And that’s where the so-called solar panels come in. But that is a subject for the next post.

Which BatteryBattery to choose for the Motorhome? Automotive vs Stationary

Almost sure your car already has a battery. So why the hell do you need to buy another battery to build your Motorhome? And what is the most suitable BatteryBattery?

First, it is worth understanding why your car has a battery. Well, your vehicle’s engine is probably powered by gasoline, alcohol, or diesel unless you have an electric vehicle. But this engine does not start by magic! For your engine to start spinning and burn fuel, you must have an ignition. This ignition can be manual, as in boat engines, lawnmower engines, or as it was done some 100 years ago when cars were invented, which is nothing more than a small electric motor that replaced the crank function. But to make an electric motor work, it was necessary … electricity. And so, the batteries began to be installed in the vehicles. That’s why when your car’s BatteryBattery is dead, that is, no charge, you can’t start it and turn it on. In addition to the starter, the BatteryBattery is also responsible for making other things work, such as headlights, arrows, the sound of your car, among others.

But the BatteryBattery is just an electrical storage device. It alone does not produce electricity. This is why your car also has an alternator, which is a device connected to the engine, and that takes some of the energy generated by burning the fuel to generate electricity. That is, the BatteryBattery helps start the engine, and the engine along with the alternator helps recharge the BatteryBattery.

But if I already have a battery in my car, why do I need to buy another one to build my Motorhome

Your car battery is designed for a specific purpose: starting the car. Therefore, it has specific characteristics, such as:

  • supply a large amount of current in a short time (which in this case are those seconds that you turn and hold the key to start the engine)
  • But in compensation, the maximum discharge designed for the automotive BatteryBattery is only 10% of its total capacity. That is, on a 100-amp automotive battery, the maximum consumption indicated would be ten amps.
  • On top of that, you would be compromising battery life, meaning it will last less. Not to mention that the automotive BatteryBattery already has a very short lifespan, which is about 2 to 3 years. Discharging your car battery a lot will make it last one year and a half or less, depending on how many times it has been misused. So if you are one of those who have the habit of forgetting the headlight or car stereo on, and the other day you have to make a direct call to recharge it, the great pacifier, know that you are ruining your car battery.

It is for these and other reasons that your car battery is not the best option for connecting electrical appliances to your Motorhome. It is best to use a stationary battery, which has properties substantially inverse to an automotive battery.

If an automotive battery lets you release full charges in a short period, the stationary BatteryBattery is designed to release constant charges over a long period, which makes it more suitable for use in a refrigerator, for example, which is on 24 hours a day. And if an automotive battery does not allow it to release more than 10% of its capacity without compromising its life, the stationary can be discharged up to 80% without the problem. On a 100 Amp stationary battery, you can consume 80 Amps without worrying. Comparing a car battery with a stationary one, it’s easy to decide which one to choose for your Motorhome, right?

In theory, yes, but the point is that stationary batteries are much more expensive than automotive batteries. However, in the medium term, it is still worth investing in a stable battery, as its useful life is approximately five years, while the car if misused, may not last even one year.

But now that I’ve convinced you that you need to buy a stationary battery, the question is: what storage capacity to choose? 

Should I buy a 100 Amp, 140, 180, or 220 Amp Stationary?

The simple answer is the more, the merrier. This is because, as I explained, the Battery is a storage device for electricity. Let’s make an analogy with your car’s gas tank. If your tank only fits 10 litres of gasoline, and your car is 10 kilometres per litre, you will only be able to drive 100 kilometres before you have to stop at a gas station. But if your tank can store 50 litres of gasoline, then you will walk 500 kilometres before you have to stop and refill the tank. You can use this same logic when choosing your Motorhome’s stationary Battery. The higher the ampere capacity, the longer the autonomy of your electrical system, and therefore the longer before you have to stop to recharge the BatteryBattery.

But since all is not flowers, the larger the capacity of a stationary battery, the more expensive it is. And since not everyone can afford 4 220-amp stationary batteries, what you can do is calculate the average consumption of your Motorhome’s fixtures to buy a battery that has the minimum capacity to meet your needs. And this is what we will do in the next article … how to make this account to buy a battery suitable for your project.

Again, I need to warn you that I am not an expert in the field of electricity. Everything I presented in this video was the result of much study and conversations with those who understand the subject. So, if I said some zucchini, tell us there in the comments below and help enrich this debate even more …

Solar Energy at Motorhome – Solar Panel

There are several ways to generate electricity. One is through a thermal power plant, where fossil fuels such as oil, coal or gas are burned to generate energy. There is also a nuclear power plant. The problem with these two types of power generation is that they pollute the environment or are dangerous, like the nuclear accident that resulted from a tsunami that happened in Japan a few years ago and you should remember.

Alternatively, these two models are renewable-based power plants such as hydro and wind power plants. But one way to generate electricity that is so high today is through solar energy. This is because the cost of solar panels has fallen so much in recent years, making it a viable alternative. And if you can install solar panels on your roof today, why not use them on the roof of your Motorhome.

In theory, if you produce more energy than you spend, you will never be in the dark. This is a motorhome owner’s big dream. The problem is that, depending on the sun, the production of energy through solar panels will vary according to the weather conditions. On cloudy days, you will have lower electricity production than on sunny days. That’s where the stationary batteries come in, which we already commented on in the last article. Thanks to Dilma, we have learned that it is not possible to store the wind, let alone the sun, but it is possible to store in your BatteryBattery the surplus produced on days with ideal conditions, and use that energy on days when production is lower.

Another issue is that solar panels do not yet have the efficiency needed to produce a large amount of electricity. To generate more energy, more solar panels are required, and the roof of your Motorhome, if it is a van, for example, will not hold a large number of plates. A recurring question of who wants to install a solar system on their Motorhome is which type of solar panel to choose. Today, the two best selling models are mono crystalline and polycrystalline. 

Monocrystalline are a little more efficient than polycrystalline, meaning they can produce a little more energy. The problem is that they are also more expensive. And in my opinion, this difference in efficiency doesn’t make up for the price. You can go for polycrystalline even though you will be well served (Road Tip =).

Another question that a lot of people have questions about is the power of solar plates. There are 150 watts, 250, 325-watt solar panels. You will find many variations in the market. In practice, the more powerful a solar plate, the larger it will be. In my case, I chose to buy two 150 Watt boards, as this way, I could place one side in front of my van and save space in the luggage compartment. But it would be the same if I had just purchased a 300 Watt solar panel.

In addition to the solar panels and a stationary battery, you will also need a charge controller, which is a device that delivers the ideal voltage and current to your BatteryBattery. Most solar panels produce a voltage of about 30 volts, and it is the charge controller that will regulate this voltage and deliver the optimal amount so as not to damage your BatteryBattery. But there are two types of charge controller: PWM and MPPT. The difference between them is that MPPT is more efficient, better able to take advantage of the load generated by solar panels and deliver up to 30% more power compared to PWM. But as my grandmother used to say, usually the best is also more expensive. An MPPT charge controller costs on average 2X more than a PWM. Still, if you want to have a more extended electric range, The MPPT controller is the most suitable, due to its superiority of efficiency compared to PWM. In that case, I would advise you to spend a little more and buy an MPPT controller (Road Tip =)

Once you have decided whether to go PWM or MPPT, it’s time to size the load controller capacity. Translating: if the controller will be 10 amps, 15, 20 amps, … (variations are not lacking in the market, and so many people are in doubt when choosing). Add the peak current your solar panels can produce, and buy a controller with a slightly larger capacity.


As stated above, travelers who choose to use a motorhome need to use electrical equipment. For this a solution, widely used in the past, were small diesel generators. However, besides being a source of non-renewable energy and extremely polluting, it becomes quite expensive in the long run.

Aiming to reduce the costs of such fuel and still cause less damage to the environment, the most considered option in the market is being solar photovoltaic.

The motor home is an Off-Grid system, and similar to the systems we find at home, it consists of: Photovoltaic solar panel, battery bank, charge controller and solar inverter. The solar panel will convert solar radiation (solar rays) into electrical energy. Such energy in turn will pass through a charge controller which will control the process of charging and discharging the batteries. Batteries are responsible for storing electrical energy generated by the panels during the day so that it can be used at night. This energy is generated and stored in direct current. Because of this, the use of an inverter is required. This inverter will convert the direct voltage into an alternating voltage that will be used by the equipment inside the motorhome.

In short, the solar panel system helps to significantly reduce energy costs. Thus, motorhome lovers are increasingly adhering to this solution.

Leave a Comment

Your email address will not be published. Required fields are marked *