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Off Grid Solar Powered RV Air Conditioning – Is it Possible?

Jason

Jason

— 10 min read
Off Grid Solar Powered RV Air Conditioning – Is it Possible?

Since we shared our very first RV solar video we’ve been asked the same question over and over:  Can I run my air conditioner with all that solar power?

We’ve always responded with a “NO” since we felt it wasn’t realistic based on the battery banks and inverters we’ve had in our previous motorhomes.  With our current RV, we installed some serious Off-the-Grid technology and for the past several months we kept thinking, maybe we can run our a/c without being plugged in?!?

An opportunity landed in our laps as we unexpectedly crossed paths with our friends John and Peter The RV Geeks near Joshua Tree National Park. It’s almost like the stars aligned: The Geeks are RV DIY install gurus, the desert temps were rising, the sun was brightly shining and the wind was calm so we could actually talk to the camera.

So, we decided to put the question to the test! Will we really be able to run our RV air conditioner off our solar setup? Let’s find out!


Please remember we’re not RV Solar or Air Conditioner professionals. We’re simply sharing our experiences and I’ve done my best to explain our test results and I hope the information below makes sense.The Test LocationJoshua Tree BLM South – Our EXACT GPS coordinates: 33.673887, -115.799702

Date: January 20, 2016

Time: 2:30 pm

Weather: Sunny with a 4mph breeze, High of 76°F Our GearHere is the equipment that we have on our RV for this Solar + A/C test:

Coleman-Mach 15 RV Rooftop Air Conditioner http://amzn.to/1QhfCfs

Magnum Hybrid 3000 watt Pure Sine Inverter http://amzn.to/1oEnA63

GoPower! Solar All Electric Kit http://amzn.to/20zo7lC

9KW Lithium Battery Bank (700 amp hours) Can You Run an RV A/C off of a Solar Setup?As I mentioned above this is one of our most common RV solar questions. I noted in the video the solar power must first go through a charge controller then into a battery bank, and finally through an inverter to get power to the Roof A/C.

Based on our results in the video, with the proper technology and modifications the short answer is YES! Should You Run an RV A/C When You’re Not Plugged In?This is probably the most important question.  Of course the answer isn’t a simple yes or no because there are too many variables to consider.

How much money are you willing to spend on your set up? How hot is it where you plan to camp? What is the humidity level? How many hours a day will you need to run the A/C? Will the A/C need to be run overnight? etc.

If you’re designing a solar setup and willing to make some upgrades it is a real possibility but not necessarily a cheap one. With our current solar/battery set up and the addition of a soft start, we would run our Air Conditioner to take the edge off the heat only when the sun is shining bright. If temperatures get too hot, or there is intermittent cloud cover, we will most likely have to run the generator or head to a campground and plug in.How to Wire your RV Air Conditioner to the InverterWe did not cover this in the video because our install was done as a temporary install by swapping a few wires and a circuit breaker.  We would not recommend this to anyone looking to create a permanent solution.  We can only recommend you take your RV to a trained and licensed technician.  If possible find one that is also knowledgeable in solar, inverters and RV 12v battery systems. What the Manufacturers SayI looked up phone numbers online and began calling all the manufacturers of the products used in my Solar A/C test.  Surprisingly most hadn’t spoken to anyone before about any similar testing in the RV world.

I thought that was pretty crazy considering I’ve seen so many people pose this question over the years.  It always amazes me how few people actually pick up the phone and contact the manufacturer when they have a question about a specific product.

Below is an outline of what I talked about with the manufacturer of each product.  It gets a little technical, so if you’re starting to gloss over you should close this toggle and click on the next one that lists our recommendations without the detail.

I contacted Magnum and asked about the fault light I received for a fraction of a second during our test.  I was told: The 12v Inverters, including the hybrid inverter, are equipped for a maximum surge of 40 amps and the A/C unit draws a minimum of 61 amps while the compressor turns on.  Magnum recommended we consider upgrading to a 24v Inverter as they can handle a much higher amp draw.  They specifically recommended their Hybrid 4000watt Pure Sine Inverter which has a surge max of 82amps.  Magnum also recommended I look into a “Soft Start” or “Easy Start” for the A/C.

I called Coleman-Mach and asked about the power draw from the A/C and they confirmed the “Locked Rotor Amps” of our Coleman-Mach 15 is 61amps.  I was told: The Locked Rotor Amps (LRA) refers to the power draw of the initial startup.  Once the Air Conditioner has been run the first time, the oil will be out of the compressor and the coils will be saturated.  This means the compressor will need less power than the initial 61a when the A/C starts back up in order to keep the RV cool.  That said, they would not recommend running our RV A/C through our exact inverter, they recommended we look into installing one of the Power Saver models, specifically the Coleman Mach 1 PS which has a 41 LRA. I asked about a Soft Starter and I was told they have successfully used the Micro-Air EasyStart in the past.

I contacted Micro-Air and asked them about their soft starters, and which one would work with our RV A/C units.  I was told: The EasyStart 3T will provide a minimum of a 50% decrease in the Locked Rotor Amp (LRA), bringing the A/C amp spike to (or below) 31a. If we installed this product, it should allow us to run our A/C using the inverter without spiking past the inverter’s 40a max.  I was also told they have documentation and can help with the step-by-step process of how to install the EasyStart in a Coleman-Mach air conditioner.

Our lithium battery manufacturer has recently been impossible to reach by phone or internet, so I contacted the US Based Lithionics Battery.  I’ve spoken with these guys many times over the years and I’m sure our next Lithium Battery purchase will come directly from them (for various reasons I’ll share in a future article).  I asked them about the potential issues that could arise from us pumping in 55amps of power while continuously pulling out 80amps of power.  I was told: The lithium batteries and the NeverDie BMS are built for applications just like this. You will not do any harm to the lithium batteries by running the RV air conditioner. As long as the battery has ample charge you can run the AC for hours.  Those statements were quickly followed up by an impromptu disclaimer that went something like this: Now I can’t speak for any other lithium battery manufacturer and I certainly wouldn’t recommend doing this with traditional batteries.

I contacted GoPower! to confirm their solar panels, wiring, MC-4 connectors and the Outback solar controller could all handle the power needed to recharge the batteries while the A/C was running.  I was simply told: That’s exactly what the AE kit was made for, you won’t damage it!

I didn’t contact Fleetwood because this was kind of a secret test, you know, one of those ”better to ask forgiveness than permission“ sorta things. The Recommended Gear to Run an A/C off Solar and BatteriesAfter discussing all the details & running through various scenarios with each manufacturer it seems like we’ve come up with this as a realistic option for running an A/C while camping ‘off the cord’.  By each item I’ve included a link so you may continue to research price, features & read reviews of each product.

Solar

With this exact setup you have the potential for a net ZERO amp draw, meaning you are putting in as much power into the batteries as you are taking out.

Inverter

You need a 3000 watt or higher inverter with a 40 amp surge rating; it does not have to be a “Hybrid” model (although if you have a big battery bank I would recommend the Hybrid models for their power share benefits).

Batteries

You’ll want a minimum of 700 amp hours of lithium battery power. The link above is the Lithionics 400ah battery, you will need to purchase two and connect them in parallel then add the BMS. If you’ve got the budget I’d consider stepping up to 900+ amp hours and if you wish to run an A/C day and night you’ll probably want to have at least 2000ah of power.

RV Roof Air Conditioner

With the EasyStart installed you can use just about any RV roof A/C unit that Coleman-Mach makes. I like this model because it uses less power, but don’t go replacing a perfectly good A/C if you don’t need to.

Soft Start

With this “Soft Start” installed you should be able to run most any rooftop RV air conditioner using a 12v inverter, even if the inverter has a 40a max surge and the A/C has a LRA of 61+. Will It Work on A Boat, Tiny House, Etc?YES! We’re in the process of testing the Easy Start on our Sailboat A/C unit now. So far it’s reducing the LRA by 70%.Other RV A/C Off-Grid SolutionsWhile chatting with the manufacturers we also tossed around a few ideas that may spark a new line of thought.  They haven’t been proven or researched, but they were agreed upon by many of the people I spoke with.  All would still need some of the “Recommended Gear” modifications like the ones listed above.  Here are my three favorite ideas:

Volta Power Systems: This is the future for RV power.  It’s a complete power system that is smaller, lightweight and substantially more powerful than current RV power systems.  The charging power comes from a high performance alternator, the power is stored in a giant Lithium Ion battery bank and the power is converted/inverted through a massive system.  Initial test reports relayed to me claim “In trials we ran 3 each 15,000BTU RVP A/C’s for +6.5 hours off the LI-ION battery bank”.  That sounds promising…and expensive!

Generator for A/C 1st Start:  1) Kick on the RV generator and let it warm up.  2) Once the power is ready (our generator takes about 2 minutes) turn on the A/C.  3) Let the A/C run for 5 minutes with the generator on.  4) Turn off the Generator and continue running the A/C by using the inverter.  This will effectively absorb the high surge from the initial A/C startup and the next A/C cycles will use less power.

Hybrid Inverter + Small Generator:  Using the “Load Support” feature of the Hybrid Inverter a small generator might be used to power the A/C unit.  Potentially something as small and compact as the Honda EU2000 could provide enough power.  The main benefit here is you can place the little generator further away from your RV so you don’t have to smell the exhaust or listen to it. What about an RV Generator?We prefer not to run the generator while wild camping because it sorta ruins it for us.  Being somewhere beautiful is fantastic, but having to listen to the constant hum and smell the exhaust fumes isn’t something we want to deal with on a regular basis.  That said, when Mother Nature decides not to cooperate (by giving us clouds instead of sun) we sometimes have to run our generator for an hour or two to make sure our batteries don’t drop too low.

Running the A/C off the generator is no problem as long as you have a powerful enough generator on board.  Our RV has a Cummins 7000 watt generator on board that has more than enough power to run both A/C units (at the same time) with plenty of power left over to run other devices within the RV.  Here’s a link to our generator: Cummins Onan RV QG 7000  We’ve also had the Diesel version in our past RVs and it works great as well: Cummins Onan RV QD 6000

I would also recommend an Auto Generator Start like this one: Cummins Onan EC-30w

Oh yea, and don’t forget the most important part of this equation: We’re only discussing running 1 A/C unit in full sun.  If your RV so large you have to run 2 or 3 A/C units to effectively cool it, or you wish to park the RV in the shade, well…I think you’ll need to tow a trailer full of solar, battery and inverters to handle it.  Or you could just run the generator or plug-in to shore power and say “fahgettaboudit”.

The missing link for us is the Soft Start. After making this video the Micro Air people decided to offer a $25 discount coupon if you use the code “GWTW” at checkout. We think that’s pretty nice so we’ve passed it along to you: www.gonewiththewynns.com/product/air-conditioning-off-grid

What do you think?  Any plans to install a giant off the grid kit to run your air conditioner?  Think we’re crazy for even suggesting it?  Share your thoughts and questions in the comments below because I know you’ve got an opinion on this RV mod.
Disclaimer – This video and post are solely based on our testing experience. We were not sponsored by or swayed by the mfrs of these items. The soft start discount was offered by Micro Air after we created this video, we receive a small commission and you get a discount so we think everyone wins.

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