Caravan Air Conditioner

Running a Caravan Air Conditioner from a Generator

There are times of the year and parts of this great country that can experience either extreme heat, or chillingly low temperatures… So, when travelling around Australia in a Caravan/Motorhome, a caravan air conditioner can come in very handy to keep your van nice and comfy inside. When you enjoy the benefits of free camping away from a caravan park and mains power, you’ll likely need to run your caravan air conditioner from a portable generator. So here is what you need to know:

Caravan Air Conditioner
a caravan air conditioner can come in very handy to keep your van nice and comfy inside

Running a Caravan Air Conditioner from a Generator:

Even though a caravan air conditioner is a fantastic addition to your vehicle, it will also likely be the most energy consuming appliance on your trip. An average caravan A/C unit consumes between 1000 to 2000 watts when running continuously and when it first starts up can consume between 2000 to 3000 watts to get the compressor going. As a point of reference, compare that to around 100-200 watts for your laptop, 50-100 watts for your fridge, and 40-50 watts for a fan.

There are less common examples of campers using their lithium battery packs, plus inverter & charger set ups (battery bundles can be found here)  to run their caravan air conditioner…whilst this might suit the minority of RV’ers, it can be expensive and for many set ups it can be uneconomical, draining your batteries very quickly!  So the most common way to run your caravan air conditioner in the absence of mains power is via a generator.

What type of Generator?

This part is easy – you’ll need an inverter generator. Inverter generators produce ‘pure sine wave’ power, meaning it is clean power that is suitable to run your sensitive electronic equipment. Because caravan air conditioners have electronic componentry, you need a clean power source which is provided by inverter generators.

Additionally, inverter generators are more fuel efficient than other types of generators as they are able to idle up and down based on the load of the appliance. Lastly, you’ll notice that most inverter generators have a ‘suitcase’ style design, meaning they are enclosed with soundproofing material making them very quiet so you don’t disturb your peaceful campsite!

Caravan Air Conditioner
Inverter generators produce ‘pure sine wave’ power, meaning it is clean power that is suitable to run your sensitive electronic equipment

What size Generator?

The answer to this is a little less straightforward, but we’ll try to make it easy for you. There’s just a few things you need to consider based on your particular make and model of caravan air conditioner and your particular situation.

Generators are rated by their maximum power output. So, a 2000 watt generator can produce a maximum of 2000 watts at peak, and will run at around 1600 watts continuously. Due to their size and weight, a lot of people want to use a 2000 watt generator, but unfortunately in many cases, this may not be enough power to start a caravan air conditioner.

Traditional non-inverter style air conditioners tend to have a high startup current and depending on the size of the compressor, may require a generator with a peak output higher than 2000W.

The 3 inverter style air conditioners from Dometic can be run by a good quality 2000W generator.

To save everyone the hassle of calling manufacturers, we have put together a table based on our extensive market research which recommends a suitable generator that we sell to run most caravan air conditioners that have been sold in Australia.

If your air conditioner is not on this table, please give a call and we will do our bet to size one for you!

Generators to Run Your Caravan Air Conditioner – Rooftop Models
Generators to Run Your Caravan Air Conditioner – Built In Models

Other factors to consider in running a caravan air conditioner from a generator?

With all of this in mind, there are a few more things to take into account when looking at a generator to run your caravan air conditioner:

Temperature: As the ambient temperature and/or humidity increases, the power required to start the air conditioner compressor is greater and the power output of a generator decreases. This means unfortunately at the time when you need more power to start the compressor, the generator is actually making less power than it is rated at due to the higher ambient temperature and humidity.

The hotter the ambient air is (the air that is sucked into the engine for combustion) the power output of the engine and generator will decrease. A good rule is to allow a 1.5% decrease in output for every 5 degree C above 25C. So on a 45 C day, a genset will be de-rated by 4 x 1.5 = 6%. Height above sea level will also cause then genset to be de-rated further.

Extension Leads: It is also suggested that a short lead from the generator into the van (no longer than 3-4 meters) is used in very hot conditions, as there is amperage drop over longer leads.
Other appliances: you will also need to bear in mind the load drawn by other appliances running at the same time as your caravan air conditioner: Battery charger, fridge, lights, TV etc. Often we find that customers who are running an air-conditioner on a generator that is only just enough to handle the air con start up requirement, will have troubles if their battery charger is plugged in at the same time for example.

So, overall, these are other considerations when selecting the right generator for your caravan, and highlights that opting for a genset with a bit of extra capacity beyond the peak draw of your air conditioner is a good idea.

Any exceptions to the rule?

Yes. There are three excepts to the rule that we know of. In mid 2016, Dometic released the Harrier Inverter Air Conditioner: featuring the first use of an inverter compressor in an RV application. This means the Dometic Harrier Inverter can help eliminate start-up current issues when running from generators or when current supply is restricted. Where most other caravan air conditioners will require more than 2000 watts at start up, the Harrier can comfortably start and run from a 2000 watt generator such as the Yamaha 2000w Inverter Generator. (It is important to note, the Harrier has now been superseded by the Harrier Plus Air Conditioner).

Dometic Harrier Inverter Caravan Rooftop Air Conditioner

In 2019, Dometic released the Ibis 4 Reverse Cycle Rooftop Air Conditioner, which improved the many industry-leading features of the Ibis 3 and incorporated them into a new light weight roof top design. Like the Harrier, the Ibis 4 uses inverter technology to eliminate start-up current issues and can be run from a 2000 watt generator. But the Ibis 4 features an industry first – it features a dual-cylinder horizontal compressor. This compressor reduces vibration in the a/c unit which reduces noise – a major benefit in most customer’s books!

Dometic Ibis 4 Review

The Ibis 4 features impressive cooling, quiet operation and an ultra sleek low profile design – no wonder it is already one of the most popular models on the market!

Dometic Ibis MK4 Reverse Cycle Roof Top Air Conditioner
Dometic Ibis MK4 Reverse Cycle Roof Top Air Conditioner

Also in 2019, Dometic released a lite version of the Harrier, targeted at mid-sized RV owners. The Dometic Harrier Lite Roof Top Air Conditioner weighs in at 36kg, and is the most efficient of the three Dometic inverter air cons on the market. The Harrier Lite is perfect for cooling vans up to 6m in length.

Recap and Generator Recommendations

Our air conditioner sizing table is the best resource to help you in your quest to find a quality generator to run your caravan air conditioner. Just bare in mind that the generators are recommended from the minimum requirement, therefore don’t be afraid to choose a slightly larger model to take into account running other appliances and other external environmental factors.

The Yamaha EF2200IS is the most popular generator to run caravan air conditioners. It will start and run most caravan air conditioner models on the market, due to being lightweight, efficient and the boost feature!

Yamaha EF2200iS – Boost function & easy reset button

Other popular models include the Cromtech Outback 2400w, the Dometic 2100W, the Yamaha 2400IS, the Briggs & Stratton 2400W, the Engel 3500W, the Briggs & Stratton P3400, and the Dometic TEC29 built-in generator. The latter 3 models being the choice for people running larger air con models and/or wanting a bit more power.

Final Word:

When you are choosing a generator for your caravan, it is recommended you opt for a quality brand that has comprehensive warranty coverage along with national service agent and spare parts support. Premium Brands such as Yamaha, Briggs & Stratton, Dometic etc. have hundreds of service agents around the country meaning that if you ever need the genset inspected under warranty, serviced or require spare parts, then you are covered.

Even a select number of budget brand generators, such as Cromtech or Maxwatt, have national service agent support. They are made in China, and the premium brand units might be slightly superior in terms of specs, but their price is compelling and you still get national service agent backing.

It is not recommended you choose a cheap no-name generator (often sold on places like eBay) that do not have national service agent support. We repeatedly get stories of these cheap brands not honoring warranty, or when something goes wrong with the generator on the road, then there are long and frustrating delays to the caravan trip as there is no service agent or spare parts support.

To find out more about generators to run Caravan Air Conditioner units, check out our range HERE.

DISCLAIMER* Please note, this advice is general in nature and we strongly recommend consulting the product manual and where relevant, a professional installer.

S Reynolds

Steve Reynolds, Power Product Expert at mygenerator.com.au is a small engine specialist with particular expertise in Generators, Water Pumps, Pressure Washers and other Outdoor Power Equipment products. Outside of work; an avid caravan enthusiast who enjoys time on the road and has gained years of familiarity with Caravan & Camping products also. A passion for power products used for work, home and leisure!

You May Also Like

Maxwatt Generator Review: How Do They Compare To The Big Brands?

Englaon TV Review: Are They Worth The Hype?

Comparing The Best Caravan Aircons

Our Guide To Front Runner Roof Racks

24 thoughts on “Running a Caravan Air Conditioner from a Generator”

  1. Love this post, if noise is a big concern for you, you should check out a quiet enclosure that silences them! See them at http://www.zombie-box.com. They are not only sound proofing but they are also portable. You are able to attach these to back trailers and RVs also.

  2. This is a very nice post. It is also very helpful for us. I have been searching this type of information because I want to get knowledge about Generator . I learned a better knowledge about that. Thanks.

    1. Hi Konrad, thanks for your question. 12,000 BTU equates to approx. 3.5kw. Therefore if your portable A/C unit surges to 3.5kw (you should check this with the A/C manufacturer) then a 3000 watt generator MAY get overloaded at that peak surge…I would recommend you speak to the A/C manufacturer technical support and clarify the exact max draw and then will know if a 3000 watt generator will be enough. Thanks.

  3. The Generator Place claim:

    “A Honda 2KVA Inverter Generator is able to start and run up to a 3.6KW air conditioning unit…You need to use a short (less than 5 Metre) 15Amp Rated Extension lead…We recommend you turn off all other appliances when you start an Air Conditioner, motor or Pump. Start Your Generator with no load, turn other appliances off, plug in your short 15 amp lead and then turn on the Air conditioning, motor or Pump. Once the big load is running you will be able to use fridges, TVs and radios. However you may not be able to use a microwave, toaster, hair dryer, heater or other high wattage appliance while the air conditioning is on – it all depends on the size of your generator. We offer a money back guarantee that the Honda EU20i will run every caravan air conditioner on the market.”

    1. Hi K, thanks for this. Part of that claim certainly supports our advice; with everything else off and short extension leads, a 2000w (2kVA) Inverter Generator can run some Caravan A/C models… HOWEVER we get customers contacting us every week saying their 2000w generator (including the Honda EU20i model) will NOT run their caravan A/C – the most common reason being that the outside temperature is a hotter than factory testing conditions, and thus the generator cannot cope with the Aircon start up requirements in the heat. This is because any generator’s capacity is slightly de-rated in hotter temperatures…which is obviously when you want your A/C running!
      So we would say that the claim you have shared fails to point out the real conditions / situation in which a caravan Aircon will need to run…

      When you take that into account, along with the fact you often you might need to run extension leads greater than 4 metres, and not to mention you might want to run other small appliances at the same time, e.g. your battery system, fridge-freezer, TV etc, then its no wonder that the best selling caravan generator models are 2400 watts or above in size. With a 2400w generator, you know with confidence the engine is large enough to handle the Aircon start up in the heat and have a bit of power contingency so you are not inconvenienced.

      Additionally, you can put a call into the technical departments of the leading caravan manufacturers such as Dometic, Truma, Air Command etc. and ask what size generator they recommend, they will advise: 2400 – 2800 watts in size.

      In summary, a 2000w generator will work for some Caravan set ups, but most are best served by a generator with slightly more capacity to handle the heat and have any extra power up your sleeve for any other de-rating factors (i.e. power chord length) and other required appliances. The exception to the rule in our experience is less commonly the generator size, but the actual Aircon model; the newly released Dometic Harrier Inverter RV A/C has an inverter compressor which significantly reduces start up power requirements and will comfortably start and run from a 2000w inverter generator.

      If you would like to discuss further, please feel free to call us on 1300 400 122. Many thanks.

      1. We run our caravans soft start inverter air-conditioner on 2 x 120AH lithium batteries, a 2000w inverter & 300 watts of solar. It can be done!!

  4. I find that my Yamaha 2800 is perfect for running my aircon in my 23ft van. Even on 40deg days. I prefer the 2800 because its smaller in size and weight compared to the 2400. And Honda models of the same compacity plus its cheaper to buy.

  5. I have a 20ft caravan with an Air Command Cormorant air con, just wondering what size generator would be the best to use? I am somewhat limited with space, thanks

    1. Hi Peter, if you were to call the technical department of Air Command (now owned by Dometic), they will advise a minimum sized inverter generator of 2400-2800 watts. This is also our recommended generator size for RV air con models such as the Cormorant. Our most popular caravan generator models in this size are:

      Cromtech 2400w Inverter Generator – budget friendly option, lightweight, great for infrequent use, 1 year warranty
      Yamaha 2400w Inverter Generator – premium brand, most popular all round caravan generator, 4 year warranty
      Yamaha 2800w Inverter Generator – premium brand, a bit more power and extra run time capacity, 4 year warranty
      Briggs & Stratton 3000w Inverter Generator – good bang for buck, popular for larger RV’s wanting to run multiple appliances, 3 year warranty

      For each of the above options, you can click on the link and look under the Specifications section for product dimensions to see which model best suits your caravan space capacity. Many thanks.

  6. Hi.

    A customer of mine is looking at running a 2kva Honda through a smart 40amp charger to a 170AGM battery, then via a 3.5kva inverter to a 2kva aircon. Your opinion would be appreciated.


    1. Hi Bruce, in our experience running a 240V RV Air Con from RV batteries via an inverter can flatten the batteries quite quickly due the power draw. Whilst some customers do this, it is far more common to run the RV Air Con unit directly from the generator (assuming the generator is suitable sized for that particular RV air con model). Many thanks

  7. Hi.
    Thanks for the above. We’re looking at running the Honda genset while the aircon is on, never from the battery alone. The Honda only supplies 8amps DC, whereas we’re intending to run it’s AC current through a 40amp battery charger, then the inverter etc.


    1. Hi Phil, if you are referring to air conditioners for RV’s (i.e Caravans, Motorhomes, Campervans etc.) then any of our Recreational Vehicle Air Con Models will run from a 2400w inverter generator or larger. So if you already have a 3500w inverter generator, then you will be fine running any modern RV air conditioner.

  8. Hello, I have read which generator you recommend for a air command cormorant, though my toolbox will only fit a Honda 2.2kva or a Cromtech 2.4kva outback.
    You recommend the Cromtech to run this air conditioner but with limited use. I would like a more quality generator for heavier use so will a Honda 2.2kva run my air conditioner please? The Yamaha 2.4kva is 29mm too wide to fit in my toolbox.

    1. Hi Paula, we have tested the Air Command Cormorant on our 2400w inverter generator models and they will do the job. We have not tested that A/C model on a 2200w sized generator. We have some customers that use a Briggs & Stratton 2200w inverter generator for their Caravan A/C unit, so based on that the Honda 2200w generator would likely run some of the RV aircon models also. We just recommend a 2400w model as we know this gives you the capacity required, especially in hotter ambient conditions which de-rate a generator’s capacity. Thanks

  9. G’day, if I want to have a snooze during lunch in my campervan (yet to be purchased) and have the aircon on (1-2hrs), is it still worthwhile getting a generator or just use car aircon by leaving engine running? In other words, would generator be cheaper to run than the car engine for few hrs? (2L petrol or 3L turbodiesel). I guess there’d be wear & tear aspect of the engine but really don’t want to be leaving portable generator outside the van during my snooze near my work. Unless i can secure it safely to the van somehow out of reach from people walking past on footpath or car park?

    1. Hi John,

      Thanks for your question.

      Most of the air conditioners in our range (https://www.mygenerator.com.au/caravan-roof-top-air-conditioners.html) run from 240V power so you will need a generator, unless you invest heavily in a batter and inverter system.

      You might want to look at this 12V parking truck cooler (https://www.mygenerator.com.au/dometic-coolair-rtx-2000-12v-truck-air-conditioner.html) that you could run direct from battery.

      Please don’t sit there with the engine running for 1 – 2 hours, it’s no good for anyone 🙂

      Please let us know if we can assist further or don’t hesitate to contact one of our product experts on 1300 400 122!

  10. Hi,
    I’m looking to power a TRUMA Aventa Comfort Mk2 AC with a Cromtech Outback CGT2500i generator that, according to the data above, should be sufficient.
    However I’m concerned the start spike input power of the AC will be to high for the generator. Truma state that the AC requires 20Amps for start-up.
    Will the Cromtech be adequate for the job?

    Cheers, Peter.

    1. Hi Peter,

      It is often the case that the manufacturer specifications display these kind of start up figures. We only know from testing and customer experience that that generator will run that AC. Ensure you don’t have your caravan battery charger or any other high drawing appliances on at the same time.


Leave a Reply

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