In this article...
Most RVs come with roof-mounted air conditioning units that run off 110V AC power. While they're known to consume a lot of power when they're running, they also have another quirk - they draw a lot more power when you first turn them on.
While this isn't an usually issue if you're connected to shore power, if you want to run your AC on a portable generator or inverter, you need to make sure it can provide enough power to start the AC, not just run it!
This issue is due to something called Locked Rotor Amps (LRA). Essentially, when the motor to run the compressor first starts, it takes a lot of power to get it going!
Although the LRA surge may only last half a second, it can be up to 5x the current draw of the compressor in normal operation, known as Running Load Amps (RLA). For example, our Outdoors RV 21RBS came equipped with an Airxcel Coleman Mach 3 Plus AC unit which is has a Running Load Amps (RLA) rating of 10.0Amps but a Locked Rotor Amps (LRA) rating of 50.5Amps! Yes - I know these acronyms are confusing!
In other words, during the first half second or so, our AC unit will pull about 50Amps, or over 5kW of power to get it going! Fortunately, our batteries and inverter can supply that (for a very short period) but it puts a lot of stress on the equipment - not ideal! As a brief aside, I did try to measure it on our monitoring system but it happens so fast that even our monitors couldn't see the power surge!
You may not be so lucky though. Your inverter or generator may not be able to supply that initial power, especially if you're at higher altitude where a generator's output is lower. In that case, you just won't be able to run your AC.
So what's the solution?
Micro-Air EasyStart 364
Enter the Micro-Air EasyStart 364. This clever little device acts as a buffer for your air conditioning unit, providing the power needed for that initial surge and ramping the compressor up slowly. In doing so, it reduces the starting current by up to 65-75%. In other words, rather than needing 50.5Amps, with an EasyStart installed your AC would need less than 18Amps to get it started!
Micro-Air sells several different models, but if you have a 110V roof-mounted air conditioning from Dometic or Coleman Mach then it's likely you'll want the EasyStart 364. Check the Micro-Air website to make sure you get the right one.
We decided to install an EasyStart 364 on our Outdoors RV 21RBS to reduce the load it puts on our batteries and inverter, hopefully helping them last longer!
Disclaimer: The Micro-Air EasyStart 364 was provided to us free-of-charge by Battle Born Batteries. We are under no obligation to review it and this article reflects our own opinions and experience.
I helped a friend of ours install one on her Airstream last July - it was very straightforward. I'm pleased to say that installing it on our RV was even easier because, not least because I can walk around on our roof unlike the solar-panel-covered Airstream!
Parts & Equipment
If your Micro-Air EasyStart 364 bundle didn't include it, you may also want to pick up the EasyStart 364 Installation Kit which comes with all the parts you'll need to install the EasyStart. The kit is pretty simple though, so you may find you already have everything you need. We bought the kit to make it easier (and because my electrical supplies were running a little low).
In addition to this, you'll need a screwdriver, a wire crimping tool, and a cloth to wipe down the area where you'll mount the EasyStart.
Lastly, I'd recommend downloading the MicroAir EasyStart installation manual specific to your model of air conditioner - there's a link on their website. I used this for the Dometic AC unit on the Airstream, and the Coleman Mach AC unit on ours - each guide was very clear with step-by-step instructions and photos.
That's it! Nothing more is needed - just basic tools. Allow 1-2 hours for the full procedure if you're taking your time and working steadily. It took me about 1.5 hours and I was working slowly to take lots of photos as I went.
Before you do anything else, make sure power is turned off completely. Turn off all your AC breakers. If you have an inverter, ensure that's turned off. If you have a generator, make sure that's turned off and unplugged if possible, and obviously disconnect and unplug from shore power.
Once you've assembled the parts and tools, take everything up onto the roof so you don't have to keep going up and down the ladder.
Depending on the AC unit you have, your installation steps will vary, but I'll walk through our installation on our Coleman Mach 3 Plus.
I removed the AC shroud by unscrewing the 4 screws on top. The two sections of the cover pull apart - I used a screwdriver to ease the tabs apart. Put it somewhere to one side where it won't blow away - it was a little windy when I did our installation!
Mounting the EasyStart 364
Before we do any wiring, the first step is to physically mount the EasyStart 364. The manual gives you several choices, depending on the layout of the coolant tubes. I chose to install ours lying down under the motor - this was the easiest location to access and would help keep it secure.
Note that the EasyStart 364 box is an IP65 weatherproof enclosure (which means "dust tight" and protected against water projected from a nozzle) so don't worry about trying to mount it somewhere that it won't get wet.
I thoroughly cleaned the area and used the adhesive strips from the kit to mount the EasyStart 364 in position, taking care to orient the wires in the right direction. While it says to use zip-ties to keep the wires tidy, I chose to do that at the end.
With this in place, I then removed the screws holding down the metal cover on top. I didn't remove all the screws at the front as I didn't need to remove the cover entirely, just raise it slightly for access. There's also a side plate that I removed for better access for wiring later.
Following the instructions, I cleaned back some of the putty around the existing wires. It was far less messy than I had anticipated!
Then I threaded the wiring harness from the EasyStart through the hole and sealed it all back up with the putty.
Now that the wires are going to the right place, follow the instructions to crimp them correctly. The EasyStart 364 has 4 wires - white, orange, brown and black.
I crimped connectors onto the white and orange wires and attached them to their respective terminals on the capacitor. Take your time to ensure the crimps are strong. It can be a little awkward to reach in to plug in the terminals, but I got there eventually!
The brown and black wires are connected with end splice connectors to other existing wires. Splicing the black wire was tricky because it was a 3-way splice with 2 other wires. I took my time, ensuring that the wires were twisted together and pressed firmly into the end-splice before crimping securely.
If your AC has an existing start cap or hard start kit, the instructions will guide you through how to remove those components. I had to do that on our friend's Airstream, but not on ours.
That's the wiring part of the installation complete. That wasn't too hard, was it?
I reinstalled the metal cover but left the plastic shroud off for now.
At its heart, the EasyStart 364 uses a capacitor to buffer the power surge. But it actually has some sophisticated electronics inside that work to minimize the surge current.
In order for this to work optimally, the EasyStart has to learn your AC system. To do this, you need to connect your RV to a reliable power source. Ideally this would be shore power, but since our AC can start with our inverter and we were boondocking at the time, we just used the inverter. I turned on the inverter and flipped all the breakers on too.
To learn, the system has to see your AC starting up 5 times. The process is simple - I turned the thermostat to Cool mode, and set the temperature low so the AC would turn on. After the compressor has run for 30 seconds, I turned the thermostat up to turn the AC off, and then instantly turned it down again.
Part of the EasyStart system means the AC won't turn on for 5 minutes after it's been turned off - to give the system a chance to recover. Once the AC had turned off, I ziptied the wires to tidy them up and reinstalled the plastic shroud.
I repeated this on / off cycle 5 times, as per the instructions. Using our WiFi thermostat, I was able to do all of this using my phone while standing on the roof.
Installing the Micro-Air EasyStart 364 was incredibly straightforward. While it took me about an hour and a half, that was mainly because I was photographing as I went. If I had to do it again, I think I could do it in less than 30 minutes.
For us, the benefit of having this installed is that our AC will place less stress on our inverter and batteries - hopefully helping them both to last much longer! But for many others, installing an EasyStart is necessary to run the air conditioning off their inverter or generator.