In this article David answers a question from a reader about how to keep their caravan cool when the air-conditioner is out of action while off-grid camping.
Hey 12V Guru,
Our caravan is an off-grid van, but we can’t run the air-conditioner for long. What can we do to fix this?
It’s a 2016 Jayco StarCraft with 180W solar panels and two 140Ah batteries.
Cheers,
Teena and Tim Goodes
(Newbies to living full-time on the road)
Hi Teena and Tim,
It’s great that you have the opportunity to live life on the road — it can be an exciting adventure — but staying comfortable in hot weather can be a challenge, especially if you’re hoping to run your air-conditioner while travelling. With limited solar power and AGM batteries, it’s important to understand your energy consumption and explore options to improve efficiency.
There are a few key factors to consider to help you get up and running with AC. In order of priority, consider how much energy your air-conditioner uses and whether you should upgrade to lithium batteries and charger, add solar panels or use a DC-DC charger.
Most caravan air-conditioners are 240V units that require between 1000 and 2000 watts (1–2kW) of power, depending on their size and efficiency. If you’re running it from a 12V battery system, you’ll need an inverter to convert 12V DC power into 240V AC power. To give an idea of the battery draw, a 2000W air-conditioner at full power on a 12V system will need roughly 160–170 amps per hour from your battery bank, especially if the van is already hot inside. Once the van cools down, it will cycle using less power. With a battery bank of 280Ah, and only using up to 50 per cent capacity, your batteries will be flat in about an hour. Even with solar panels replenishing some charge, it’s unlikely you’ll be able to run the air-conditioner for long without additional charging sources.
I imagine that the air-conditioner, being less efficient than newer versions, will not be kind to the lifespan of your batteries.
With AGM batteries and a limited number of solar panels, your system is likely designed for running lights, fans and a fridge — not high-powered appliances like an air-conditioner.
So, to run the air-conditioner when off the grid, you’ll need more energy storage and charging capacity. Here are your best options:
1. Upgrade to lithium batteries:
Lithium batteries have higher usable capacity (they can be discharged to 90 per cent versus AGM’s 50 per cent) and can handle higher discharge rates, making them better suited for running an air-conditioner. A 400Ah lithium battery bank would give you significantly more runtime than an equivalent AGM setup — roughly three times more than your current capacity.
2. Add more solar panels:
You’ll need a larger solar array. A 2000W air-conditioner will require at least 800–1200W of solar panels to run efficiently. More solar means recharging your batteries faster and keeping the air-conditioner running longer. Since roof space is limited, you might also consider portable solar panels or solar blankets to boost your charging capability when stationary.
3. Install a DC-DC charger:
While driving, you can use your vehicle’s alternator to charge your batteries using a DC-DC charger. These chargers convert power from your vehicle’s alternator into a suitable voltage for charging your house batteries. They help keep your batteries topped up while driving, reducing reliance on solar alone. A 40A DC-DC charger can significantly improve your charging ability and extend the runtime of your air-conditioner.
4. Check if your charger is suitable:
Hopefully, your charger will be able to handle lithium battery charging requirements. Most Jayco vans in 2016 had a BMPRO system installed, many of which are upgradeable without removing the entire system. When increasing your solar and battery setup, you must consider upgrading your fusing and cabling to handle the additional current.
Running an air-conditioner solely on battery power for extended periods can be problematic. Making these suggested should give you a more efficient setup for life on the road.
Happy cool travels!
12V Guru
THE NEXT STEP
If you want to learn the latest caravan news, find the most innovative new caravans and camping gear or get inspired to plan your next adventure off the beaten track, subscribe to our weekly newsletter. We promise to send you only the best content.
Related articles:
12V Guru: Future-proofing your next caravan’s 12V setup
12V Guru: Correct storage for lithium batteries
12V Guru: Tips for running AC on limited battery power