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The differences between 220V and 12V motorhome air conditioners

It is always nice to be able to travel with one’s own home in tow, which is why motorhomes and vans are increasingly the ideal solutions for travelling, on holiday, and why not, even for living in, just think of the growth of digital nomads in recent years.
But what happens when it gets hot?
Unless you travel to cold countries, sooner or later you will need a system that allows you to withstand the hottest summer temperatures, so what do you do?

There are different solutions, but the one we want to talk about today is the roof-mounted air conditioner for motorhomes and vans.
There are two types of rooftop air conditioners today: the ‘classic’ 220V air conditioner and the Viesa Holiday 12V evaporative air conditioner.

In order to understand real consumption and whether it is really possible to freely use one solution rather than the other, we must first understand how electricity works inside our recreational vehicle.

Service battery

Our motor home is equipped with two batteries, a starter battery (which serves the engine) and a services battery.
The services battery is the one that uses the cell, to which, for example, the entire lighting system, the motorhome pump, etc. is connected.

How to recharge the services battery?

The battery services is recharged while driving by the vehicle’s alternator, or by any solar panels installed on the roof of our motorhome, or while parked directly from 220V electricity (e.g. camping). In this case, however, the voltage must be converted from 220V to 12V via a battery charger, which normally consumes 200/300W.

The effective consumption of a roof-mounted air conditioner for motorhomes

This brought us to the consumption of the motorhome air conditioner. We took the official data of a ‘traditional’ air conditioner among the smaller ones and compared it with Viesa Holiday, and here is the result:

220 V2,7620
Data transformed to 12 V51612
VIESA HOLIDAY X (average consumption)Ampere per hourWatts
Data transformed to 220 V0,0715,40
12 V1,2915,48

To ensure a correct comparison, we converted from 220V to 12V and the reverse to have values for a same level comparison.
We see that Viesa Holiday at 220 V would consume 0.07 Ah against 2.7Ah or 15.4 W against the 620 W of the ‘traditional’ air conditioner.

Clearly, Viesa Holiday has significantly reduced consumption compared to the classic 220V motorhome air conditioner. In fact, Viesa consumes a tenth of the energy of a classic roof-mounted air conditioner, resulting in a 90% energy saving.

However, let’s go ahead and try to understand if and how we can use our conventional or 12V air conditioner, both on the camping site and in the wild.

How electricity works on a campsite

Are you in a camping site, you’ll be connected to a power tower (normally 1Kw, i.e. 1.000W). So anything we connect to our system that runs on 220V will draw its energy from the post we have available and, in the meantime, we will also charge our service battery, thanks to our battery charger.

Let’s have a little diagram to better understand.

For those who love the classic air conditioner, then, the problem might appear to be solved if you only go camping, but is this reality?

Let’s do the math:
As we said before, a camping or caravan area power station can offer around 1,000W, now let’s do a simple addition:
+620W consumption of ‘classic’ air conditioner
+250W average consumption of a charger (we have talked about this before)
Total 870W

Well, we have 1,000W at our disposal so we have about 100W left over… but is it really like that? Not exactly, if you have already experienced this yourself you will know that the energy available never corresponds to what you ‘should have’, but is around 600/800W. If you are then in the summer season, on an even moderately crowded campsite, things get even more complicated.

It is like having a 100 megabit ADSL line, even if nominally the declared speed is 100 megabits, it will never be the real speed (due to a thousand factors) and if we want to surf online on the weekend it will be even lower. The exchange is unique for a certain number of users, and therefore the more users that connect simultaneously on the same exchange, the less availability I will have, the exact same thing happens at the campsite with the electricity.

The more campers, vans or caravans are connected to the campsite’s power line, the less power I will have, with the consequence that I will not be able to connect any other devices, most likely not even the air conditioner itself.

There are some alternatives, such as solar panels. Let’s look in greater detail at what happens by harnessing renewable energy.

Solar panels and electricity in motorhomes

Going back to the table of consumption of rooftop air conditioners at the beginning of the article, to run a classic 220V motorhome air conditioner, at least 7 solar panels of 100W each would be required, this under optimal conditions (peak sun, perfectly perpendicular to the panel, etc).
Since optimal conditions are only achieved for a few hours a day, at least 1 or 2 more panels will be needed! This energy will be stored inside the service battery. In order to be able to run the air conditioner at 220V, we will need to convert the energy back from 12V to 220V, and we will therefore need to add an inverter to do this (with associated consumption, costs and space requirements).

With the Viesa Holiday evaporative air conditioner, this doesn’t happen because it consumes very little and connects directly to the service battery. Since Viesa is already 12V, no inverter is needed, and it will draw the necessary energy directly from the service battery.
If we are camping connected to the 220V column, we won’t need to add any consumption to what is already being drawn by the charger, and we will have the total availability of the energy provided by the column itself.

So, with Viesa Holiday IIIs, there’s no problem whether camping or off-grid.If we have a solar panel, we won’t even have to worry about consumption anymore. A single 100W solar panel will be sufficient, unlike the 7-8 panels needed for a traditional 220V air conditioner. Plus, it will even leave us with surplus energy to recharge the service battery!

*Infographic referring to the consumption of the previous version Viesa Holiday 3s (with Viesa Holiday X the consumption is even lower).

With Viesa Holiday, not only do you save in terms of consumption, but also in terms of purchasing additional devices like solar panels and inverters. Additionally, you save space and weight, as only one solar panel is sufficient

We haven’t mentioned yet that Viesa Holiday is the lightest roof air conditioner for campers, weighing only 11.3 kg compared to an average of over 30/35 kg for traditional 220V air conditioners. This translates to additional fuel savings and a significant advantage in terms of weight (which we know is always a crucial factor for campers).

But it doesn’t end there. Assuming we don’t have access to 220V power or solar panels, but only a 100A service battery (provided with our camper, so no additional expense), at maximum speed, Viesa Holiday X consumes only 3.95 Ah, and at minimum speed (for example, at night), 0.35 Ah, leaving us with all the autonomy we’ll need.

Which camper air conditioner to buy? Is a traditional 220V better or Viesa Holiday 12V?

We have seen how Viesa Holiday is definitely the ideal air conditioner for campers and vans in any situation, even when completely off-grid and on the road.
It must be said, however, that the traditional air conditioner is different from the evaporative system of Viesa Holiday, so those who prefer the ‘refrigerator’ effect will continue to prefer traditional systems, albeit not without some difficulties.
With Viesa Holiday, the effect will certainly be different—no temperature fluctuations and no limits. Instead, we will have total freedom, enjoying a natural and refreshing comfort, anywhere and in a very simple way.

So, the question to ask before purchasing an air conditioner for a camper or van is: will I really have the energy I need to make it work?

Based on the answer, I can choose the system that best suits my needs.

*Infographic referring to the consumption of the previous version Viesa Holiday 3s (with Viesa Holiday X the consumption is even lower).