When you’re travelling through the Aussie outback or parked up at a sunny coastal campsite, having a working air conditioner inside your van can feel like pure luxury. But powering it—especially when you’re off-grid—means knowing exactly what size inverter you need to run a caravan air conditioner safely and efficiently.
It’s one of the most misunderstood topics in van life. Too small, and the inverter trips or overheats. Too big, and you’ve wasted cash on something you’ll never fully use. So let’s break it down.
Whether you’re upgrading caravans in Heatherbrae or looking to improve your off-grid setup, here’s how to get the right inverter for your cooling needs.
What an Inverter Actually Does
Before we get into sizing, it’s worth understanding what an inverter does in a caravan setup. Simply put, an inverter converts 12V DC power from your battery into 240V AC power, which is what most appliances—like air conditioners—require.
Without an inverter, you’re limited to 12V accessories (like lights and USB ports). With the right inverter, you can run air cons, kettles, microwaves, and even TVs.
But air conditioners are a unique beast. They have high startup demands, and continuous power requirements that differ by model. So sizing an inverter isn’t as simple as reading the sticker on the side.
Understanding Startup vs Running Wattage
Air conditioners typically draw a high burst of power at startup, known as surge or peak wattage. After that, they settle into a lower continuous or running wattage.
For example:
- A typical caravan air conditioner might run at 1300W
- But at startup, it could spike to 2500–3000W
Your inverter needs to handle both loads, even if just for a few seconds at startup. This is where many setups fail—people buy an inverter based on running wattage alone.
Here’s a general breakdown of typical caravan air con power specs:
| Air Conditioner Type | Running Watts | Startup Surge |
|---|---|---|
| Compact rooftop (e.g. Dometic) | 1000–1300W | 2000–2500W |
| Mid-range split system | 1300–1800W | 2500–3000W |
| High-capacity rooftop | 1800–2200W | 3000–4000W |
That’s why choosing an inverter that handles surges comfortably is essential.
Minimum Inverter Size for Most Caravan Air Cons
As a general rule, you’ll need:
- A pure sine wave inverter
- With a minimum 3000W continuous rating
- And 6000W peak (surge) capability
Why so big? Because even though your air con might only “run” on 1300W, that startup demand is what matters most.
Going below a 3000W inverter often leads to:
- Tripping breakers
- Overheating cables
- Damaging your battery
- Or simply no cooling at all
It’s better to oversize slightly than to underpower and risk system failure.
Pure Sine Wave vs Modified Sine Wave: Why It Matters
Air conditioners are sensitive appliances that don’t like rough or inconsistent power. That’s where the pure sine wave inverter comes in—it delivers smooth, grid-like power that mimics household electricity.
Modified sine wave inverters, on the other hand, can damage electronics or cause air cons to operate inefficiently or not at all.
Never try to run a caravan air con on anything less than a pure sine wave inverter. It’s not just about comfort—it’s about protecting your gear.
Pairing the Inverter with Your Battery Bank
Here’s where things get practical. A big inverter is only useful if your battery bank can keep up. Running a 240V air conditioner off a 3000W inverter will:
- Draw roughly 250–300Ah per day (depending on usage)
- Require lithium batteries for sustained high current
- Demand beefy cabling and solid DC–DC charging support
Here’s a sample setup that works well:
- 2 x 200Ah lithium batteries
- 3000W pure sine wave inverter
- 40A DC–DC charger
- 600W+ solar panels
- 50mm² cabling with quality lugs and fuses
This kind of setup can support a few hours of air con per day, provided you’ve got good sun or alternator input to top up your battery.
Solar Considerations: Can You Run It on Solar Alone?
Yes and no.
Solar alone won’t run an air conditioner in real time unless:
- You’ve got massive solar capacity (800–1000W+)
- Perfect sunshine conditions
- A powerful MPPT solar controller
But even then, it’s not consistent or sustainable for extended air con use.
More realistically, solar helps recharge your battery so you can run the air con for a few hours, especially in the evening. The smarter approach is to:
- Run the air con briefly when needed
- Use solar to replenish energy during the day
- Rely on shade, fans, and insulation for passive cooling
Top Inverter Brands for Caravan Air Conditioner Setups
Inverter quality matters. Here are a few brands well trusted in the Aussie caravan scene:
- Victron Energy – Durable, expandable, highly programmable
- Enerdrive – Aussie-tough, well supported, plug-and-play options
- Redarc – Built for Aussie travel, integrates with battery systems
- Projecta Intelli-Wave – Mid-range reliability, value for money
Avoid cheap inverters from eBay or Amazon with inflated wattage claims. If the price sounds too good to be true—it is.
Look for:
- Internal cooling fans
- Fault protection
- Proven performance under Australian heat and conditions
Caravan-Specific Alternatives: Soft Start ACs and Hybrid Systems
Some newer caravan air conditioners include soft start technology. These reduce startup surges dramatically—meaning you might get away with a 2000–2500W inverter.
Brands like Dometic, Truma, and Air Command have developed AC units with lower draw and better efficiency for off-grid use.
You can also consider hybrid setups:
- Small AC + rooftop fans
- Portable inverter + generator backup
- Air conditioning via 240V hookup at parks, inverter for everything else off-grid
The key is balance—match your cooling needs with your battery and inverter capabilities, and build from there.
FAQs
Can I run a caravan air conditioner off a 2000W inverter?
In most cases, no. A 2000W inverter typically won’t handle the startup surge of a standard caravan air conditioner, which often exceeds 2500W.
Some low-draw AC units with soft start may work, but you’ll still be pushing the limits. It’s safer and more practical to go with a 3000W inverter or higher to avoid faults and give your system breathing room.
How many batteries do I need to run an air conditioner in my caravan?
That depends on how long you want to run the AC and how efficient your setup is. For example:
- Short-term use (1–2 hrs/day): 200Ah lithium
- Moderate use (3–4 hrs/day): 400Ah lithium
- Full-time cooling: 600Ah+ lithium + generator support
Lead-acid batteries aren’t suitable for this load—they discharge too quickly and have limited usable capacity. Lithium is the only serious option.
Is it safe to run a caravan air conditioner while driving?
Only if you have the proper setup. Running an air con from a 12V inverter while driving requires:
- DC–DC charger to replenish battery from alternator
- Appropriate fuse protection
- Inverter wired to a secure mounting point
Some people use a generator or engage air con only when parked. If you’re running it underway, make sure airflow to the unit isn’t obstructed and cables are safely routed.
Can a generator replace an inverter for air con?
Yes. A portable generator (2kVA–3kVA) can easily run most caravan air conditioners without the need for inverters or complex battery systems.
Pros:
- Reliable off-grid power
- No battery drain
- Good for long stays
Cons:
- Noisy
- Requires fuel
- Can’t be used in national parks or quiet areas
Generators are a solid backup but not ideal for full-time air con use if you’re chasing peace and quiet.
What else can I run off a 3000W inverter?
A 3000W inverter opens the door to:
- Caravan air conditioners
- Microwaves
- Coffee machines
- Kettles
- Induction cooktops
- Power tools
- TVs, laptops, fans, chargers
You still need to watch how many of these you run at the same time. Add up total wattage and make sure you’re under the inverter’s rated limit—including surge loads.
Keeping Your Cool the Smart Way
When it comes to caravan comfort, air conditioning can make or break the experience. But getting it right means investing in the right inverter, not just the air con itself.
A properly sized inverter—paired with a capable battery bank and smart usage habits—lets you travel Australia in comfort, even through the hottest months.
Start your journey with confidence — visit 7th Street Caravans or give our team a call on 02 4012 6009 for friendly, local advice.