Can you run your RV's air conditioner on battery power?
Can I run my RV AC on solar?
Can you run your RV’s air conditioner on solar/battery power? If it’s even possible how long can you run it? How many solar panels do you need? We did an experiment with our own MasterVolt system and our Coleman Mach 15,000 BTU RV roof-top air conditioner to get the answers.
But, first let’s look at some facts and information.
You can’t run an RV air conditioner on solar
A lot of people ask how long you can run an RV air conditioner on solar power. There’s a simple answer. You can’t.
Just as you can’t run your car on a gas pump. And, essentially, for the same reason.
What the solar is there for is to provide power to recharge the battery in your RV. The solar you have, or might be considering, provides power to a solar charge controller that, in turn, feeds the battery in your RV which recharges that battery. Or batteries.
From there the battery has the power reserves that you’ll use to run the RV’s air conditioner. But, in most cases, you first have to convert the power that’s in the battery into something the AC can use.
Most RV air conditioners, including the one in our trailer, run on 120vac household power. The assumption is that, if you’re running RV air conditioning, you’re doing so on shore power and that shore power is 120 volt AC.
So the battery in our RV feeds an inverter that changes the 12 volt power in the battery into 120 vac power that the air conditioner uses. Now we can run the air conditioner. More on this below.
So, how long did our RV air conditioner run?
Our RV solar and lithium system
It’s important to lay the ground work on what we have in our trailer. Our system, installed by ABC Upfitters, is a MasterVolt power system consisting of a 460 amp-hour lithium battery, MasterVolt’s Combimaster converter and a well-matched system of wires and fuses.
The air conditioner we have is the Coleman-Mach 15,000 BTU roof-top air conditioner and it does not have a soft start. Many people will recommend this technology which allows the AC unit to ramp up its power demands more slowly but we didn’t put one in for a few reasons; the Combimaster can provide bonus power to ramp-up the AC and, well, this air conditioner is going away soon.
How long I ran the air conditioner
We started out with our MasterVolt battery at 100% (duh) and then kicked-on the converter. Know that just converting the power from the native 12 volt in the battery to the 120 vac that the AC needs does consume some power.
I set the air conditioner to 75°F and it was pretty warm outside - somewhere in the upper 80s. Also, it was a beautiful day without any real clouds so sun exposure could’t have been better. In fact, the circumstances of the day were perfect for this experiment.
I have an accompanying chart here that shows the power consumption versus time for the experiment. Note that there are two entries on the chart that show the power consumption at zero. Like almost all devices that change temperature including the AC, furnace, refrigerator and so many others, the RV air conditioner cycles on and off. Those times where I came in and there was no draw were times when the trailer had reached the temp the thermostat was set for and the AC had cycled off.
As you can see the air conditioner in our RV consumes about 1400 watts when it’s running which is equivalent to things like hair dryers, microwaves and that sort of thing.
But also see that at 1:13p.m. and 2:37p.m. there was power output of zero watts from the system. That’s because, at those times, the AC had achieved the goal of making the interior of the RV 75° as dialed-in on the thermostat and the AC cycled off as it was supposed to. So, the less you demand from the AC, the lower the overall power consumption and this makes it so clear.
The math here is mathing properly - a 460 amp-hour 12 volt battery like the one we have has about 5,500 watt hours of power in it. There’s about four hours of power to run the thing at a continuous load. But because the system cycles plus there’s also power coming in, I got about six hours of run time more or less. I stopped the experiment after five hours with the battery at 32% state of charge.
What can I do to change this?
First of all, the Coleman-Mach air conditioner is a common component in RVs. But it’s been around a long time.
Studies show that more and more of us are interested in off-grid camping so the inefficient and noisy air conditioners we’ve become accustomed to aren’t cutting it.
Yes, you could add more battery power. Or you could run a generator. But I’d rather reduce the consumption and have something more efficient. So I ordered a Furrion Chill Cube. But so did enough other people that I have to wait. And wait.
The Furrion Chill Cube is a direct drop-in replacement for the Coleman Mach and is remarkably efficient, quiet and just a better unit. It’s sort of modern like your car is modern compared to that AMC Pacer you saw at the car show.
But at the recent Overland Expo I also saw a number of air conditioners that did run directly on 12 volt power. I also saw units that ran on 48 volt power and there are some RVs now that are running natively on 48 volt power.
Dometic showed off a 48 volt system that could run on battery power but when I asked if/when I could buy one the answer was effectively never. You can get ‘em in Australia but not here now.
What can you do?
Its’ less expensive to replace your RV’s air conditioner with one that’s quieter and significantly more efficient than it is to add more solar panels and greater battery capacity. Much more.
In addition to the Furrion Chill Cube we also saw Cruise N Comfort USA air conditioners that ran at 12, 24 and 48 volt power at the recent Overland Expo West.
RV supplier Truma, too, has a very efficient unit in their Truma Aventa which they will gladly install for you but it has to be at one of their facilities, which means a trip to Indiana. Not that that’s a bad thing, we love going there.
I also saw a new 48 volt system in the Grand Design Lineage VT Class B RV which was a mini split system designed for RVs. I got to speak with Stephan from Grand Design who detialed how ruggedized that AC system is - plus it puts out 20,000 BTU of cool compared to the 15,000 in my own RV. But that system is currently only in that Grand Design RV and is not a direct drop-in replacement for the typical RV air conditioner.
I see the number of companies interested in making inverter-based highly efficient RV air conditioners is growing and I’m sure there are mainstream companies working on this now.
If you want to run an air conditioner in your RV on battery power it is possible today but the future holds a great deal of promise that’s actually realistic.
